Consensus statement

IOC consensus statement on recommendations and
regulations for sport events in the heat
Sebastien Racinais      ,1 Yuri Hosokawa      ,2 Takao Akama      ,2
Stephane Bermon      ,3 Xavier Bigard,4 Douglas J Casa      ,5 Andrew Grundstein      ,6
Ollie Jay      ,7 Andrew Massey      ,8 Sergio Migliorini,9 Margo Mountjoy,10
Nebosa Nikolic,11 Yannis P Pitsiladis      ,12 Wolfgang Schobersberger      ,13,14
Juergen Michael Steinacker,15 Fumihiro Yamasawa      ,16
David Anthony Zideman      ,17 Lars Engebretsen,18 Richard Budgett19

ABSTRACT
This document presents the recommendations developed
by the IOC Medical and Scientific Commission and
several international federations (IF) on the protection
of athletes competing in the heat. It is based on a
working group, meetings, field experience and a Delphi
process. The first section presents recommendations for
event organisers to monitor environmental conditions
before and during an event; to provide sufficient
ice, shading and cooling; and to work with the IF to
remove regulatory and logistical limitations. The second
section summarises recommendations that are directly
associated with athletes’ behaviours, which include the
role and methods for heat acclimation; the management
of hydration; and adaptation to the warm- up and
clothing. The third section explains the specific medical
management of exertional heat stroke (EHS) from the
field of play triage to the prehospital management in a
dedicated heat deck, complementing the usual medical
services. The fourth section provides an example for
developing an environmental heat risk analysis for
sport competitions across all IFs. In summary, while
EHS is one of the leading life- threatening conditions for
athletes, it is preventable and treatable with the proper
risk mitigation and medical response. The protection
of athletes competing in the heat involves the close
cooperation of the local organising committee, the
national and international federations, the athletes and
their entourages and the medical team.

INTRODUCTION
Major  international  sporting  events,  such  as  the
Olympic  Games,  face  numerous  challenges  in
providing  optimum  healthcare for  athletes. As  the
Summer  Olympic  Games  and  most  summer  sport
international  federation  (IF)  events  are  often  held
during the hottest months of the year, one important
athlete health challenge includes the prevention and
treatment of heat- related illnesses.1 2

Irrespective of the environment, muscle contrac-
tions during physical activity produce vast quantities
of  heat,3  which  lead  to  an  elevated  core  tempera-
ture  after  only  a  few  minutes  of  exercise.4  If  the
environment allows for skin surface heat dissipation
(eg,  via  convection,  radiation  and  sweat  evapora-
tion) to counterbalance the rate at which metabolic
heat is produced, then core temperature will reach

Key points

 ⇒ Protecting the athlete’s health and safety during
sport events in the heat requires involvement
and collaboration among the local organising
committee, the national and international
federations, the athletes and their entourages
and the medical team.

 ⇒ The local organiser should monitor and

communicate the environmental conditions
before and throughout the event, provide
sufficient ice and hydration and propose
adequate heat stress mitigation facilities (eg,
shade and recovery areas).

 ⇒ The athlete should specifically prepare for the
expected environmental conditions (ie, heat
acclimation), manage their health status before
the event and plan their hydration, cooling,
warm- up and clothing according to the risks
associated with the forecasted environmental
conditions.

 ⇒ Medical providers should receive specific

training on exertional heat stroke management
including early recognition (eg, field of play
supervision and finish line triage) and diagnosis
(including rectal temperature assessment) as
well as in the use of rapid on- site whole- body
cooling (ie, cool first, transport second).
 ⇒ International federations are encouraged
to develop specific environmental heat
policies with a clear communication pathway
on the level of risk and the associated
countermeasures (eg, using a colour- coded 1–5
heat stress scale).

a  plateau  (often  ~38.5–39°C,  depending  on  the
intensity  of  exercise).  However,  if  the  heat  dissi-
pation capacity of the athlete is limited due to hot
and/or humid ambient conditions, and/or clothing
and protective equipment worn, then the resultant
thermal strain will induce additional cardiovascular
strain  leading  to  a  decrease  in  self- selected  abso-
lute exercise intensity.5 6 The levels of performance
impairment and health risk for a given environment
are specific to the heat production of the sport and
its  heat  dissipation  capacity  (eg,  clothing),  along
with the characteristics of the athlete (eg, body size

 ► Additional supplemental
material is published online
only. To view, please visit the
journal online (http:// dx. doi.
org/ 10. 1136/ bjsports- 2022-
105942).

For numbered affiliations see
end of article.

Correspondence to
Dr Sebastien Racinais,
Research and Scientific
Support Department, Aspetar
Orthopaedic and Sports
Medicine Hospital, Doha, Ad
Dawhah, Qatar;
 sebastien. racinais@ aspetar. com

Accepted 4 September 2022
Published Online First
23 September 2022

© Author(s) (or their
employer(s)) 2023. Re- use
permitted under CC BY- NC. No
commercial re- use. See rights
and permissions. Published
by BMJ.

To cite: Racinais S,
Hosokawa Y, Akama T,
et al. Br J Sports Med
2023;57:8–25.

8

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Racinais S, et al. Br J Sports Med 2023;57:8–25. doi:10.1136/bjsports-2022-105942

and  heat  acclimation  status).7  Although  numerous  well- trained
athletes  will  transiently  achieve  core  temperatures  in  excess  of
40°C (and even 41°C) when competing intensely in hot ambient
conditions, most will remain healthy and asymptomatic.8 9

Nevertheless,  heat  is  responsible  for  more  deaths  than  all
other natural disasters combined,10 and severe exercise- induced
heat illness (ie, exertional heat stroke (EHS)) is one of the two
main  causes  of  death  in  athletes.11  12  Unfortunately,  the  level
of  environmental  heat  stress  experienced  by  elite  athletes  will
continue  to  rise  in  the  coming  years  due  to  a  combination  of
the  increased  prevalence,  intensity  and  duration  of  bouts  of
extremely hot weather (ie, heat waves) that are occurring due to
climate change and sport globalisation leading to more compe-
titions being organised in extremely hot climates. While there is
a  multitude  of  mitigation  strategies  that  can  effectively  reduce
the risk of one’s vulnerability to exercise heat stress (eg, acclima-
tion), implementation of these strategies remains insufficient in
sport settings.13 In addition, as sport events continue to be held
in extreme heat, we must ensure that evidence- based treatment
of  EHS  is  implemented  to  maximise  survival  from  this  poten-
tially lethal medical condition.14

This  document  presents  the  consensus  recommendations
from  the  panel  of  experts  and  stakeholders  convened  by  the
IOC  Medical  and  Scientific  Commission  to  protect  athletes
competing in the heat. These recommendations were established
following  the  Delphi  method,  including  contributions  from
several IF along with clinical and academic experts. The recom-
mendations are also informed from the experience gained during
the  recent  2020  Summer  Olympic  Games  in  Tokyo.  Although
some of these recommendations may require logistics only avail-
able at international/elite events, all athletes and organisers are
advised to apply as many as they can.

METHODS
Panel selection
The  IOC  created  the  ‘IOC  Adverse  Weather  Impact  Expert
Working Group for the Olympic Games Tokyo 2020’ in August
2018  (including  11  members).  This  group  worked  for  3  years
ahead of the Games to develop heat mitigation related recom-
mendations,  and  this  document  is  the  legacy  of  its  work.  The
group also identified the discrepancies in the indices and policies
used  by  different  IFs  as  a  challenge  leading  up  to  the  Games.
This  was  discussed  during  a  meeting  of  the  Association  of  the
Summer Olympic IF in 2019, and seven IFs were invited to the
final IOC consensus meeting held in September 2021. Academic
experts, with experience in establishing heat policies for interna-
tional competitions, were also invited to this meeting. Of note,
six members of the panel were also part of the IOC Medical and
Scientific  Commission  Games  Group  and  three  were  working
for  the  Tokyo  Organising  Committee  of  the  Olympic  and
Paralympic Games (see author contribution).

Evidence review
The  previous  IOC  consensus  statement  on  thermoregulatory
challenges  for  high- level  athletes  included  four  modifiable
factors:  hydration,  acclimatisation,  warm- up  and  precooling,
and  clothing.15  Similarly,  another  consensus  recommendations
on  training  and  competing  in  the  heat  included  four  sections:
acclimation, hydration, cooling and recommendations for event
organisers,7 and the most recent review on exercise under heat
stress  also  covered  three  mitigation  strategies:  acclimation,
cooling and hydration.6 In addition to the aforementioned topics,
risk  mitigation  strategies  concerning  event  operation  based  on

Consensus statement

the IFs’ experiences and the recent 2019 World Athletics Cham-
pionships and 2020 Summer Olympic Games were incorporated
in the current review. These points have been grouped under the
following  three  categories  by  the  target  population  for  imple-
mentation: (1) event organisers, (2) the athlete and their entou-
rage and (3) the medical services. The purpose of this document
is  not  to  recreate  existing  reviews  on  this  topic  but  rather  to
provide  actionable  recommendations  for  future  events.  Thus,
only a brief narrative review is included before each recommen-
dation to refer the reader to existing studies and reviews.

Consensus process
As per the Delphi method, the exploration phase was followed
by an anonymous evaluation phase. Each recommendation was
first  reviewed  by  at  least  two  members  of  the  group  and  then
assessed  online  (Qualtrics)  by  every  member  of  the  group  for
validity, feasibility and clarity using a 1–9 Likert scale. A higher
score  indicated  a  recommendation  being  more  valid,  feasible
or  clear.  Recommendations  with  an  average  score  <4  were
discarded, recommendations with a score ≥7 were retained and
recommendations with a score in- between were revised before
entering  the  second  round  of  scoring.  In  addition,  the  online
assessment offered participants the opportunity to provide open
comments about each recommendation, which were taken into
account  during  the  revision  process.  Following  the  first  round
of  scoring,  12  recommendations  received  a  score  between  5.9
and 7 in at least one of the assessment categories. Those recom-
mendations were amended, and eight scored higher than 7 in all
categories, while four scored 6.8 or 6.9 in one category. Those
recommendations  were  further  amended  and  validated  by  the
two  leading  authors.  Lastly,  one  recommendation  was  added
after the Delphi process to fill a gap that was identified during
the manuscript writing process. This revision was approved by
coauthors. Of note, most of the agenda for the in- person meeting
(September 2021) discussed the areas without consensus, such as
the exploration of developing standardised heat policies across
IFs.  An  agreement  was  reached  on  the  third  day  of  discussion
and  a  method  for  heat  policy  development  is  proposed  below
(section 4). This specific section is expert informed rather than
literature based.

SECTION 1: RECOMMENDATIONS FOR RISK MITIGATION BY
THE ORGANISERS
Environmental monitoring
For  the  IFs  or  IOC  to  accept  a  bid  for  an  international  event,
and for the athletes and their entourage to prepare appropriately
for a given sport event, they should have access to the historical
weather information for the location of the event. The environ-
mental parameters should also be recorded throughout the event
to allow the IFs to adapt the implementation of their heat policy
accordingly (see further). In addition, the different competition
surfaces  and  the  environment  surrounding  the  fields  of  play
(FoP)  induce  diverse  microclimatic  environments16  17  that  may
differ  from  established  weather  stations.18  Thus,  the  measures
should be representative of the FoP,19 at approximately 1.2–1.5 m
above  the  surface  (or  at  a  depth  of  40 cm  for  water  tempera-
ture)  to  represent  the  conditions  experienced  by  the  athlete
(figure 1),20 and should include all the parameters required by
the  IF  to  implement  their  heat  policy.  The  instruments  should
be  in  a  fixed  position  such  as  on  a  tripod  (and  not  handheld)
and  use  well- established  sensor  technology21  that  provides
accurate  and  stable  measurements  with  sufficient  resolution  to
meet  decision- making  thresholds.  Measurement  variability  due

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Racinais S, et al. Br J Sports Med 2023;57:8–25. doi:10.1136/bjsports-2022-105942

Consensus statement

Figure 1  Environmental condition monitoring and reporting. Panels
A and B: devices specifically developed for World Athletics and for
the Australian Open Tennis tournament, respectively. These are the
recommended solutions. Panels C and D: commercially available units
used on the field of play. It is not recommended to use a hand- held
device (panel C) when the device was stored in the shade between
measurements as it led to a 2°C error compared with the stationary
device. The device should be fixed on a tripod prior to the event to allow
for some time to equilibrate to the environment for accurate measures
(panel D). Panel E: the display of wet bulb globe temperature (WBGT)
monitor and risk category prepared by the Tokyo Organising Committee
of the Olympic and Paralympic Games. This display may confuse the
athletes as most do not know the WBGT and may misinterpret it as air
temperature. Furthermore, the colour coding was different from what
has been implemented by various international federations. Panel F:
colour- coded 1–5 Heat stress scale developed for the Australian Open
Tennis tournament by the University of Sydney. It provides the actual
index (value) and the corresponding recommendation. This feedback
method provides a clear message for athletes and is recommended.

to  independent  factors,  such  a  fluctuation  in  an  air  tempera-
ture measurement due to intermittent wind, should be avoided.
Data should be sampled in real- time and time- averaged appro-
priately for each individual variable (eg, longer for black globe
temperature than ambient air temperature). Sensors should also
be  maintained  and  calibrated  according  to  manufacturer  spec-
ifications  and  regularly  inspected.  In  the  case  of  the  wet  bulb
globe temperature (WBGT), there are many commercially avail-
able  options,  but  most  do  not  respect  the  original  standards.
For  example,  WBGT  requires  a  true  measure  of  natural  wet
bulb  temperature,  a  dry- bulb  thermometer  shaded  by  a  struc-
ture eliminating effects of thermal radiation and with mechan-
ically  aspirated  ambient  air  and  a  black  globe  with  a  diameter
of  15 cm.  Although  most  portable  devices  do  not  match  those
specifications (eg, no aspirated ambient air temperature, smaller
black globe), it is recommended to use a device classified under
category 1 (have black globe and natural wet bulb temperature
sensors) or category 2 (have a black globe and humidity sensor)
by  the  Japanese  National  Institute  of  Occupational  Safety  and
Health,  with  an  accuracy  within  of±2°C  (online  supplemental
appendix 1).22 23 The provision how the environmental measure-
ments are taken (including sampling rate and average span) and
who  records  the  measurements  should  be  clear,  as  well  as  the
mode of communication and the recipient of this information.
An  example  of  the  standard  operating  procedures  drafted  for
the 2020 Summer Olympic Games is included in online supple-
mental appendix 1. Of note, while IFs are encouraged to develop
their own risk analyses due to the WBGT limitations (see below),
WBGT is currently used by several IFs to guide their heat safety

10

guidelines and recommendations7 and was measured by several
IFs during the 2020 Summer Olympic Games (including tennis,
triathlon and athletics). Among IFs, there is no common WBGT-
based  limit/regulation.  Human  heat  balance  studies  show  that
even  under  the  same  environmental  conditions  (eg,  identical
WBGT  or  temperature/relative  humidity),  factors  like  meta-
bolic heat production (eg, marathon vs archery), clothing/equip-
ment  worn  and  air  movement  (natural  or  self- generated  wind
speed; eg, running vs cycling) that vary among sports can affect
heat  stress.24–28  Studies  have  shown  the  effectiveness  of  using
WBGT- based  event  modification  decisions  to  reduce  the  risk
of exertional heat illness29 and to identify resources (eg, volun-
teers, equipment and consumables) required at athlete medical
stations.30

Recommendations
 ► The  historical  weather  data  (at  least  temperature  and
humidity) of the city/area should be provided at the time of
the bid for at least the 10 years preceding. Those data are
commonly available from airport weather stations or public
databases and allow an overall estimate of potential extreme
heat risk.

 ► If the range of the historical data suggests any risk of extreme
heat,  the  environmental  parameters  relevant  to  those  used
by  the  IFs  (eg,  WBGT)  should  be  continuously  monitored
on  the  FoP  (eg,  one  value  at  least  every  hour)  every  year
for the period of the competition from the time that the bid
becomes successful until and throughout the competition. As
the feasibility of this recommendation depends on numerous
factors, it can be adapted while maintaining its essence. For
example,  if  the  FoP  has  not  been  built  yet,  the  recordings
could be done in proximity or similar surroundings.

Ice supply
Ice  is  used  at  different  time  points  (eg,  pre- event,  during  and
postevent),  in  a  different  format  (eg,  cold  water  immersion
(CWI), ice- towels, ice- socks, crushed ice and ice cubes) and by
different  stakeholders  (eg,  sports  teams,  athletes,  officials  and
medical  personnel).  It  is  therefore  important  to  plan  for  the
provision  of  a  sufficient  quantity  of  medical  ice.  For  example,
a  single  medical  ice  bath  requires  30–35 kg  of  ice  at  first  plus
continuous  renewal  to  maintain  the  ice  bath  temperature
between 5°C and 15°C.

During  the  2020  Summer  Olympic  Games,  the  quantity  of
ice was determined based on: (i) venue setting, (2) competition
schedule, (3) the number of athletes, (4) the number of medical
ice baths and recovery ice baths, (5) the number of FoP medical
tents  and  (6)  empirical  analysis  of  the  amount  of  ice  used  in
pre- Olympic  events.  Figure  2  summarises  the  ice  provision  by
sport during the 2020 Summer Olympic Games. These numbers
would need to be adapted to the event configuration and envi-
ronmental  conditions.  It  is  the  Local  Organising  Committee’s
(LOC) responsibility to have a contingency plan to supply addi-
tional ice in times of urgent need, as was the case for the race-
walk  competitions  at  the  2020  Summer  Olympic  Games.  In
addition to the total of >22 tons of ice used at the competition
venues during the 2020 Summer Olympic Games, ice consump-
tion reached as much as 2200 kg per day for the Athlete Village
Polyclinic.  Moreover,  there  were  three  ice  machines  located
in  the  polyclinic  in  the  Olympic  Village,  and  the  athlete  resi-
dences were also provided with at least one ice machine; each
machine  producing  1200 kg  of  cubed  ice  per  24  hours.  More-
over,  at  the  opening  of  the  Olympic  Village,  42  tons  of  cubed

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Consensus statement

and 10 000 m races; and World Triathlon improved the number
of  aid/drink  stations  numbers  during  the  run  course  with  a
maximum distance of 1.25 km between aid stations. Some adap-
tations, however, require advanced planning by the LOC, such
as enlarging a road section along a cycling road race course to
accommodate a feeding station.

Of  note,  while  one  could  argue  that  there  is  no  need  for
an  athlete  to  have  access  to  more  fluids  than  1 L/hour  due  to
the  limited  gastric  emptying  rate  (see  below  ‘Fluid  intake
in  competition’),31  the  provision  of  in- competition  feeding/
refreshment stations also supports the midevent athlete cooling
strategies. Indeed, a study conducted during the 2019 Athletics
World  Championships  showed  that  most  athletes  (93%)  had
a  midcooling  strategy,  consisting  mainly  of  head/face  water
dousing  (65%)  and  cold- water  ingestion  (52%).32  The  LOC
is  also  an  important  stakeholder  in  assisting  athletes  in  their
planned precooling methods. For example, athletes often use ice
vests32  for  precooling,  a  technology  requiring  a  phase  change
material to be maintained in a frozen state before use. However,
security measures may impede a team from installing a freezer in
the secure competition zone after the security sweep. It is there-
fore  paramount  for  national  teams  and  IFs  to  agree  ahead  of
time  with  the  LOC  if  any  structural  changes  are  required  (eg,
providing  power  for  the  cooling  devices)  and  how  to  accom-
modate the security provisions. However, personal preferences
(eg,  specific  hydration  and  cooling  products)  are  not  an  LOC
responsibility.

Recommendations
 ► Plan for the necessary space, power supply, ice supply and
security authorisation for the installation of cooling devices
(eg, freezer, ice slushy machine).

 ► Although not possible in all sports, consider if the FoP and/
or  the  competition  rules  of  the  event  could  be  adapted  to
allow in- competition access to fluid.

 ► Although not possible in all sports, consider if the FoP and/
or  the  competition  rules  of  the  event  could  be  adapted  to
accommodate  in- competition  access  to  cooling  interven-
tions such as additional break time in team/racket sports and
shade in waiting and warm- up areas.

Adapting competition distances and durations
A common belief is that shortening an event may minimise the
risk  associated  with  heat  stress  in  athletes.  Though  it  is  true
that  short- duration  events  such  as  sprinting  are  not  negatively
impacted by heat stress,33 this does not apply within prolonged
events of different durations. For example, the organiser of the
Tel Aviv marathon cancelled the full marathon in 2013 due to
a  heat  wave  but  authorised  the  half- marathon  resulting  in  one
death  and  20  hospitalisations.34  Indeed,  the  main  determinant
of  heat  strain  level  in  athletes  is  the  exercise  intensity,  and  it
has  been  shown  that  elite  cyclists  actually  reached  higher  core
temperature  during  a  40–45 min  time  trial  than  during  a  road
race  of  several  hours.9  As  such,  the  Falmouth  Road  Race,  a
running event of only 7 miles (11 km), is notorious for its very
high rate of EHS.35 Moreover, while shortening an event is tech-
nically possible in some sports (eg, the running of the women’s
triathlon Olympic test event was shortened from 10 km to 5 km
in 2019), this may not be feasible in other sports (eg, a cycling
finish line requires time to be designed, secured and installed).

In sports structured to permit extended or additional pauses
(eg,  tennis,  soccer  and  sailing),  introducing  more  structured
breaks  and/or  longer  breaks  is  a  relatively  common  feature  of

11

Figure 2
Ice provision per sport during the 2020 Tokyo Summer
Olympic Games. Panel A: values in kilogram per venue. It does not
account for the ice provided at the polyclinic and the Olympic Village.
Panel B: example of ice storage facilities during the event.

ice were delivered and stored in the large ice containers in the
residences  of  each  building.  Some  teams  stationed  outside  the
Olympic Village also secured their own ice- making machines in
their camps.

Recommendations
 ► Although  its  benefits  for  non- heat- related  issues  is  equiv-
ocal, ice is commonly required by all stakeholders (eg, IFs,
National Federations, sports, officials, medical, media, etc).
These requirements should be recognised and accounted for
to avoid shortage in case of heat- related issues.

 ► A vendor, method of transport (ie, cold chain in good sani-
tary  conditions)  and  considerations  for  mobilising  existing
resources (ie, moving ice from one venue to another) should
be  preplanned  in  case  of  shortage  for  treating  heat- related
issues.  The  venue  coordinator  needs  to  be  empowered
(including  financial  and  security  clearance)  to  activate  this
plan on request of the venue medical officer.

Removing regulatory and technical limitations for in-
competition hydration and cooling
In- competition  hydration  is  limited  by  various  constraints,
including  access  to  fluids.  Therefore,  several  IFs  have  imple-
mented  changes  to  their  rules,  often  known  as  a  heat  policy,
which  allows  the  official  in  charge  to  alter  the  competition
format to facilitate athlete hydration and cooling. For example,
FIFA rules allow a hydration and cooling break after 30 min of
play in each half of a football (soccer) match; the International
Tennis Federation rules allow an additional 30 s for each change
over in a tennis match as well as a 10 min break after the second
set; the Union Cycliste Internationale rules allow one car- feeding
during  a  cycling  time  trial;  the  World  Athletics  rules  allow  for
the installation of a refreshment table on the track for 5000 m

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Consensus statement

extreme  heat  policies  in  these  sports.  However,  relatively  few
physiological  studies  have  assessed  optimal  break  frequency
and  duration  across  different  sports.  Nevertheless,  it  has  been
shown that while short (90–180 s) breaks alone provide a limited
cooling  effect  if  athletes  cannot  be  relocated  to  a  cooler  envi-
ronment,36 such breaks enable the application of active cooling
strategies  such  as  ice  towels  and  additional  opportunities  for
rehydration with cool water.37 38 In the context of football (3 min
breaks after 30 min play in each half) and tennis (standard 90 s
breaks after every odd numbered game, and a 120 s break after
each set), cooling strategies during these breaks have successfully
attenuated the rise in core temperature.37–39 Extending half- time
breaks  in  soccer  by  5 min38  and  in  rugby  by  8 min36  have  also
been  shown  to  permit  greater  reductions  in  core  temperature
relative to regular half- time durations.

Recommendation
 ► A  hasty  relocation  of  the  finish  line  may  alter  the  quality
of the medical services on arrival and is not recommended
except if this scenario has been integrated into the planning
of the event, trialled (eg, during a test event) and approved
by  the  chief medical officer, the  organising  committee  and
the IF.

 ► Reducing  competition  duration  could  however  be  consid-
ered if this allows to substantially reduce the risks associated
with heat  without  increasing the risk associated with exer-
cise  intensity  or  altering  the  level  of  care  at  the  event  (eg,
reducing the running part of an Olympic triathlon from 10
km to 5 km by performing one lap instead of two).

 ► In sports structured to permit extended or additional pauses
in  play  (eg,  tennis,  football/soccer),  breaks  can  be  used  to
apply active cooling strategies such as ice towels, which can
reduce the physiological heat strain of the athlete.

Mist
Spray mist cooling using misting fans is a cooling strategy that
involves vaporising droplets of water into the air. These drop-
lets evaporate and cool the air by removing heat via the phase
change of liquid water to water vapour.1 Studies have shown that
spray  mist  cooling  can  reduce  ambient  air  temperatures  from
1°C  to  12°C,  depending  on  the  mister  design,  environmental
conditions  such  as  humidity  and  air  movement  and  proximity
to  the  mister.40  Strong  air  movement  can  reduce  the  effective-
ness of spray mist cooling by dispersing the droplets and cooling
tends  to  be  larger  in  drier  environments,  although  it  has  also
been effectively used in humid climates.40 Thus, optimal cooling
seems to be obtained when operating misting fans at an ambient
air temperature >30°C, relative humidity <70% and wind speed
<3 m/s.40 The use of misting in poorly ventilated enclosed spaces
may  increase  ambient  humidity,  which  in  turn  could  attenuate
evaporative cooling from the skin and paradoxically worsen heat
strain. While most of these studies have been conducted in urban
environment designs, misting fans have also been reported to be
a very efficient half- time cooling strategy in rugby league.36

Spray misting can be used to reduce heat stress in mass gather-
ings.41 42 For someone exercising, misting fans could also enhance
evaporative  heat  loss  from  the  skin  without  additional  perspi-
ration1 and have been reported to improve thermal comfort in
sport and leisure settings.36 40 As such, misting was implemented
in some warm- up areas during the 2020 Summer Olympic Games
(eg, rowing; figure 3). It has also been reported that some race-
walkers may choose to use a misting shower.43 However, misting
showers  are  generally  not  implemented  in- competition  as:  (i)

12

Figure 3  Example of heat mitigation strategies by the Tokyo
Organising Committee of the Olympic and Paralympic Games. Panel
A: misting of the boat preparation area. Panel B: shading of the warm-
up area. Panel C: shading of the field of play. Panel D: shading of the
mixed- zone. Panel E–F: cold bath for recovery at a sport venue and at
the polyclinic, respectively.

their cooling effect may be limited in athletes who have already
reached full skin sweat coverage; (2) the exposure time would be
very limited; and (3) they pose a variety of concerns including
water- soaked  shoes  and  socks,  an  increased  risk  of  accidents
during  sports  such  as in cycling due to  a slippery  road  surface
and the interference of vision for athletes wearing glasses.

Recommendations
 ► While  their  effectiveness  depends  on  set- up  and  environ-
mental  conditions,  misting  fans  can  be  appropriate  for
providing  a  cooling  effect  for  mass  gatherings  and  specta-
tors, especially at high temperature with low humidity and
air movement (eg, queuing lines).

 ► Misting  fans  may  be  appropriate  for  providing  a  cooling
effect in the warm- up area, or in- game break areas for racket
or team sports but should be placed in a way that athletes
can choose to use them or not.

Surface colour and material
Mega- events  are  organised  in  large  cities  where  ambient  air
and  surface  temperatures  are  several  degrees  higher  than  in
surrounding  rural  areas;  a  phenomenon  called  an  'urban  heat
island'.44  While  the  built  environment  (eg,  tall  building)  can
shade the direct short- wave radiation from the sun, open spaces
are  also  required  to  dissipate  the  heat  trapped  between  build-
ings.45  Similarly,  while  the  use  of  high  albedo/reflection  mate-
rials  has  been  promoted  to  decrease  the  surface  temperature,
the  reduction  in  air  temperature  may  not  offset  the  increased
radiant load, manifested as a greater mean radiant temperature,
that  reflective  surfaces  induce.46  47  For  exercising  athletes,  it  is

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important  also  to  consider  the  potential  effects  of  lower  wind
velocity due to the surrounding buildings48 and spectator stands
on their potential for heat dissipation.

Recommendation
 ► To date, most studies that investigated the use of high albedo/
reflective surface materials have focused on thermal comfort
and  heat  load  in  pedestrians,  and  the  effectiveness  of  such
measures for exercising athletes is inconclusive.

Shading
Direct solar radiation has a profound influence on the level of
prevailing  heat  stress  in  an  outdoor  environment.  Black  globe
temperature, which is used to help determine the mean radiant
temperature—one  of  the  four  fundamental  environmental
parameters  that  define  a  thermal  environment—is  often  10
to  15°C higher  than  the  ambient  (shaded)  temperature  in  the
middle of a clear summer day. The subsequent radiant heat load
can  exacerbate  physiological  heat  strain  and  be  detrimental  to
exercise performance.49 50 Moreover, as for heat stress,51–54 high
levels  of  solar  radiation,  especially  when  directed  towards  the
head, may also affect complex motor–cognitive tasks.55 56

Shading,  provided  by  lightweight  utility  canopies/awning
or  customised  sails,  is  a  simple  and  effective  intervention  that
mitigates  the  negative  effects  of  the  additional  heat  load  from
thermal  radiation.57  While  for  most  sports  shading  cannot  be
applied  on  the  FoP,  it  serves  as  a  key  heat  stress  mitigation
measure  for  athletes  during  mandated  rest  breaks  in  play  and/
or for athlete warm- up and cool- down areas (figure 3). Shading
coverage  should  be  sufficient  to  accommodate  the  number  of
players  on  the  FoP  for  the  given  sport,  permit  natural  ventila-
tion  from  prevailing  winds  from  any  direction  to  maximise
convection  and  preferably  constructed  of  material  with  reflec-
tive  properties.1  Shading  is  also  important  for  officials,  staff
and  volunteers  exposed  to  the  sun  on  the  FoP.  When  shading
is limited, a rotation in work shifts should be planned to allow
adequate relief time from the heat for these personnel.

Recommendations
 ► While  shading  may  not  be  possible  on  the  FoP,  the  prepa-
ration (eg, rigging area in sailing), recovery (eg, in- between
or after events) and postevent (eg, mixed zone) areas should
provide shade for the athletes.

 ► Shading  should  also  be  provided  to  all  officials,  staff  and
volunteers  on  the  FoP.  If  not  possible,  a  rotation  in  work
shifts should be organised.

Recovery and postcooling
Athletes  commonly  use  CWI  for  recovery,  and  their  use  post-
competition  is  common,  especially  following  heat  stress.58
However,  their  benefits  during  training  have  been  challenged
due to a potential delay in muscle recovery and training adap-
tation.59  60  Recent  observation  from  the  2019  Athletics  World
Championships  showed  that  more  than  half  of  the  endurance
athletes planned CWI postrace (unpublished). CWI for recovery
is an essential complement to the medical CWI for EHS but has
a  different  rationale.  Appropriate  triage  will  direct  all  athletes
with minor heat exhaustion to the recovery ice bath, allowing to
spare the medical ice bath within the heat deck for the EHS.61

For  example,  while  the  recovery  area  is  under  the  Sport
Department, which is independent from the Medical Depart-
ment  within  the  Olympic  Games  operational  structure,  it
appears important for the efforts to be coordinated between

Consensus statement

the two departments to avoid ice shortage (see previous) and
assure that the recovery area may support the clinical needs.
It  is  necessary  to  supervise  (and  reassess)  the  athletes  using
CWI  themselves  to  recover  from  heat  exhaustion  as  their
status may change to EHS. Thus, a clinician (eg, physiother-
apist and athletic trainer) should be supervising the recovery
CWI area and have a radio to call the medical station in case
of an athlete who was initially triaged as minor heat exhaus-
tion deteriorates and requires transfer to the medical station.
In the event of an athlete suffering EHS in a sporting venue
without  a  heat  deck,  the  medical  team  may  also  choose  to
annex the recovery area for emergency cooling (figure 3).

Recommendation
 ► Sporting  events  in  hot  ambient  conditions  should  plan
a  shaded  or  indoor  recovery  area  with  CWI,  with  (para- )
medical supervision. This recovery CWI area can accommo-
date the minor heat exhaustions to spare the medical CWI
area within the heat deck for the management of EHS.

SECTION 2: RECOMMENDATIONS FOR RISK MITIGATION BY
THE ATHLETES
Of  the  cohort  of  athletes  exposed  to  similar  hot  conditions
during  a  given  event,  only  a  minority  will  require  medical
support.13  While  there  is  interindividual  variability  in  both
the acute responses to heat and heat acclimation kinetics, all
athletes  can  and  should  adapt  and  prepare  for  the  heat.62–64
There  is  also  a  growing  evidence  showing  that  the  recent
health status of the athlete (especially if the athlete is experi-
encing diarrhoea) is a major risk factor for an adverse medical
outcome when competing in the heat.13 65

Acclimation
Hot  ambient  conditions  limit  an  athlete’s  capacity  to  dissi-
pate  the  heat  produced  by  the  contracting  muscles  in  the
environment, therefore imposing thermal and cardiovascular
stress  limiting  exercise  capacity.6  66  Fortunately,  repeated
exposures to heat allow for specific physiological adaptations
allowing  to  minimise  this  thermal  and  cardiovascular  stress
via  an  enhanced  sweat  response,  a  lower  decrease  in  plasma
volume,  electrolyte  conservation  and  a  range  of  other  adap-
tations described previously.67 68 This process, to train in the
heat, is referred to as heat acclimation when using simulated
environments  such  as  hot  rooms,  saunas  or  baths  and  heat
acclimatisation when exposed to naturally hot areas/environ-
ments.69 The term ‘acclimation’ is used throughout this docu-
ment as a generic nomenclature for both. Generally speaking,
a ‘heat acclimation session’ is when an individual exercises in
the  heat  with  a  core  body  temperature  between  38.5°C  and
39.8°C for at least 60 min,70 along with elevated skin tempera-
tures,  sweating  and  skin  blood  flow.7  Heat  acclimation  is
considered  one  of  the  primary  countermeasures  to  protect
the  athletes’  health  and  performance  in  hot  environments.7
Research studies have consistently reported that performance
in the heat increases after days/weeks of training in the heat,71
or that athletes are less likely to suffer a heat- related medical
event  when  they  are  acclimated  to  hot  ambient  conditions
when  required  to  do  intense  exercise.65  72  The  physiolog-
ical and performance benefits of heat acclimation have been
extensively covered in numerous recent narrative reviews,67 73
meta- analyses,68 consensus statements,7 15 Delphi consensus74
and practical recommendations.70

13

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Racinais S, et al. Br J Sports Med 2023;57:8–25. doi:10.1136/bjsports-2022-105942

Consensus statement

Recommendations
 ► Athletes  should  heat- acclimate  before  competing  in  hot

ambient conditions.

 ► The  preferred  method  of  heat  acclimation  is  to  train  in  a
similar  hot  environment  to  the  competition;  however,  if
athletes  cannot,  other  methods  (eg,  overdressed  training,
passive  heat  exposure)  that  increase  the  core  and  skin
temperature,  stimulate  profuse  sweating  and  increase  skin
blood flow can be used as an alternative.

 ► The optimal duration of heat training/exposure to acclimate
is 60–90 min per day for at least 2 weeks but shorter/other
duration can still invoke powerful positive heat acclimation
changes and should not be discarded under the premise that
they are not optimal.

 ► The recommended frequency for heat- acclimation session is
of at least four sessions per week to induce heat acclimation
and two sessions per week to maintain it.70 75

Tapering and maintaining acclimation
While  the  principles  of  heat  acclimation  are  relatively  well
understood,  and  it  has  clearly  been  shown  that  performance
is increased after 1 or 2 weeks of training in the heat,71 several
athletes  are  still  reluctant  to  modify  their  usual  precompeti-
tion  training  plan  (eg,  altitude  camp,  taper  period  and  travel
arrangements)  to  accommodate  heat  acclimation  just  before  a
competition. Given that the decay of acclimation appears to be
slower than its induction,76 those athletes could acclimate up to
1 month in advance and then briefly reacclimate for a few days
before  competing.77  78  Indeed,  a  subsequent  acclimation  stim-
ulus within a month of a first stimulus induces faster and greater
adaptations.76 79 It is also possible to minimise the decay in the
acclimation phenotype between the heat- acclimation period and
the competition by maintaining regular active (or even passive)
heat exposures.75 78

Recommendations
 ► If athletes cannot heat- acclimate in the 2 weeks preceding a
competition, they can schedule their heat- acclimation period
~1 month  earlier  to  accommodate  their  final  preparation
(eg,  taper,  travel  requirement)  and  then  reacclimate  a  few
days before the event (while minimising the decay of adapta-
tion in- between using biweekly heat exposures).

Hydration principles
Healthy humans are generally well hydrated80 with a day- to- day
variation in total body water of 0.2%–0.7% of body mass.81 82
However, the rise in sweat rate when exercising in the heat can
dramatically  change  this  fluid  balance.  A  reduction  in  total
body  water  is  associated  with  a  decrease  in  plasma  volume
and  an  increase  in  plasma  osmolality83  that  will  increase  the
core  temperature  threshold  for  vasodilation  and  sweating,84  85
reduces  the  sweat  rate  for  any  given  core  temperature86  and
decreases  cardiac  filling  and  challenges  blood  pressure  regula-
tion.87–89 Dehydration will therefore exacerbate the rate of heat
storage  and  cardiovascular  strain  imposed  by  exercising  in  the
heat, thus reducing exercise heat tolerance.90–92 Given the poten-
tial  limit  in  accessing  and  ingesting  fluid  during  the  competi-
tion (see further), the general principle of hydration should be
to  avoid  hypohydration  (less  than  2%  body  mass)  during  the
periods  of  training  in  the  heat,  especially  immediately  before
and  during  intense  training  and  competition  exercise  in  the
heat.  Any  increase  in  fluid  consumption  should  be  progressive
and not limited to competition day as an acute increase in fluid

14

absorption may first increase the urine production.93 The fluid
needs  for  an  athlete  training  in  the  heat  are  highly  individual
but consistent within the individual when influencing variables
are consistent. Fluid needs should be adapted based on changes
in  body  mass  and/or  plasma  osmolality  and/or  urine  specific
gravity. Hydration measures should be obtained in the morning
to avoid confounding effects of recent diet and exercise.94 The
following examples can also be used as a general guide at first
before individualised data are ascertained: 6 mL of fluid per kg
of body mass every 2–3 hour,7 or 2 L per day plus 1–2 L per hour
of exercise plus 1 L for each 5°C increase in ambient temperature
above 21.5°C.95

Recommendations
 ► Hydration  capacity  during  exercise  itself  is  limited;  there-
fore, athletes should ascertain sufficient fluid intake "out of
exercise", from the days before and throughout the period of
training/competing in the heat.

 ► A simple way to monitor hydration status during a period of
training/competing in the heat is to follow the weight–urine–
thirst principle with daily monitoring of body mass (changes
should  remain  <1–2%),  urine  specific  gravity  (should
remain  <1.020)  or  colour  and  thirst.  If  available  to  the
team, plasma osmolality (<290 mmol/kg) can be included in
cases of suspected chronic dehydration.

Fluid intake in competition
Sweat rate and body mass changes are highly variable between
athletes participating in a given sport32 96 97 making any recom-
mendation  on  an  absolute  fluid  quantity  complex.7  98  Sweat
rates will also change for a given individual depending on the
environmental  conditions  (ie,  temperature,  humidity,  wind
and  sun  exposure),  metabolic  rate,  clothing  worn  and  heat-
acclimation  status.63  99  While  some  athletes  may  sweat  ~1 L/
hour,  others  may  sweat  >3 L/hour,96  97  100–103  an  amount
likely  higher  than  what  athletes  can  absorb  during  exercise.
Indeed,  fluid  consumption  has  been  estimated  at  ~0.5–0.7 L/
hour  for  the  elite  marathoner  and  ~1.1 L/h  for  the  elite  race
walk  (20 km).32  104  Even  if  athletes,  such  as  tennis  players  (ie,
frequent breaks) or cyclists (ie, carrying their water bottle), have
more opportunity for hydration, there is also a limit in gastric
emptying  rate.31  While  emptying  rate  may  be  higher  in  some
large  athletes,  values  of  ~1 L/hour  have  been  reported  while
exercising in the heat.105 Therefore, hydration should not aim
to fully compensate for the sweat loss during competition but
rather to limit the level of dehydration.7 98 To do so, while there
is a debate regarding the need to follow a hydration plan versus
drinking to thirst,106–108 the vast majority of elite athletes have
a hydration strategy based on personal experience.32 Body mass
changes  are  however  highly  variable,  even  between  athletes
of  the  same  level  of  participation  in  the  same  competition.32
Lastly, hydration does not have to be linear through time. For
example, a cyclist may focus on early hydration to account for
the delay in absorption, allowing him or her to limit fluid intake
during  the  final  climb  for  body  weight  advantage.  Personal-
ising  in- competition  hydration  strategies,  however,  require
accounting for the rules of the sport, fluid storage and transpor-
tation logistics. Furthermore, beverage temperature becomes an
important factor since cool beverages (10°C–15°C) are reported
to increase the volume of fluid consumed over a given period of
time and improve performance.109

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Racinais S, et al. Br J Sports Med 2023;57:8–25. doi:10.1136/bjsports-2022-105942

Recommendations
 ► Given  the  limit  in  fluid  consumption  and  absorption  in
competition,  the  primary  focus  is  to  avoid  beginning  a
prolonged exercise bout in a hypohydrated state.

 ► During intense prolonged exercise in the heat, body water
mass losses are normal. Hydration should aim at only mini-
mising these losses (especially at the beginning of the event)
but  without  increasing  body  weight  during  the  event  (ie,
overhydration).

 ► Irrespective of being thirst driven or preplanned, any hydra-
tion strategy needs to be practised at training during similar
intensity  and  environmental  conditions  and  using  similar
beverages before being implemented in competition.

Rehydration for recovery
Rehydration  is  an  important  component  of  recovery,  espe-
cially after exercising in the heat. When a rapid replenishment
is  wanted,  athletes  have  been  suggested  to  consume  150%  of
body mass losses in the hour following exercise cessation.110 111
However, such rapid rehydration is infrequently necessary and
is  not  always  feasible  considering  gastrointestinal  limitations.
In most cases, athletes may replace 100%–120% of body mass
losses.7 Postexercise rehydration is achieved through both fluids
and  foods  and  should  also  account  for  the  other  losses  during
exercise  such  as  electrolytes  (see  next  paragraph),  carbohy-
drate112–114 and amino acids.115 For example, for lactose tolerant
individuals, chocolate milk is an appropriate recovery drink with
a carbohydrate- to- protein ratio of 4:1, contains sodium116 and
may also better restore fluid balance after exercise than a stan-
dard carbohydrate- electrolyte sport drink.115 117

Recommendations
 ► Rehydrate after exercise- heat stress with an amount slightly

above (eg, 100%–120%) the body mass loss.

 ► Consider  that  fluid  can  also  be  provided  by  food  (eg,
cucumbers,  tomatoes,  watermelons  and  strawberries)  and
that rehydration is one aspect of the recovery diet that also
includes sodium, carbohydrates and protein.

Electrolytes
Sweat includes electrolytes, mainly sodium118 119 and therefore
sweat loss cannot be compensated by water alone. ‘Heavy’ and
‘salty’  sweaters  have  been  recommended  to  include  sodium  in
their diet before, during and after exercising in the heat (eg, 3.0 g
of salt added to 0.5 L of a carbohydrate- electrolyte drink).7

The  sports  drinks  provide  moderate  levels  of  key  electro-
lytes  (eg,  sodium)  to  help  replace  sweat  losses  and  increase
the  voluntary  intake  of  fluid.  Timing  of  the  use  of  electrolyte
supplements  can  include  pre- exercise  hyperhydration,  some-
times beneficial before a race in hot conditions.98 Symptomatic
exercise- associated hyponatraemia (blood sodium <125 mEq/L)
can occur in endurance events. Contributing factors to exercise-
associated  hyponatraemia  include  overdrinking  of  hypotonic
fluids  and  excessive  loss  of  total  sodium  before,  during  and
sometimes even after the event.120

The Institute of Medicine80 has recognised that public health
recommendations  to  limit  sodium  ingestion  should  not  be
applied to individuals with elevated sweat loss due to exercising
in the heat. While exercise- associated muscle cramps are mainly
due  to  premature  muscle  fatigue121  and  not  salt  depletion,122
exercise in the heat may also promote muscle cramping in some
athletes,13  probably  when  the  sodium  deficit  reach  20%–30%
of the exchangeable sodium pool.123 Thus, most athletes should

Consensus statement

include a solution with 0.5–0.7 g/L of sodium in their hydration
plan  when  exercising  >1 hour.111  124  125  Sodium  supplementa-
tion may be increased to 1.5 g/L for athletes prone to exercise-
associated muscle cramping in the heat,126 or rather 1.5 g/hour
as organoleptic properties of beverages are affected if the sodium
concentration  is  >1 g/L.  As  for  postexercise  recovery,  this  can
be  achieved  through  a  combination  of  fluids  and  solid  foods.
Consuming  beverages  with  sodium  and/or  a  small  amount  of
salted  snacks  or  sodium- containing  food  at  meals  will  help  to
stimulate thirst and retain the consumed fluids.127

Recommendations
 ► The  public  health  recommendations  to  limit  salt  intake
do  not  apply  to  athletes  who  experience  profuse  sweating
during periods of training/competing in the heat.

 ► For a ‘salty sweater’, it is also possible to use sodium supple-

mentation for exercise lasting >1 hour.

Carbohydrate
Energy  availability  may  not  be  the  limiting  factor  when  exer-
cising  in  the  heat,128  as  high  ambient  temperatures  reduce  the
overall capacity to perform a prolonged exercise.129 Fluid inges-
tion  during  exercise  in  the  heat  should,  therefore,  focus  on
maintaining  optimal  hydration  status  rather  than  on  substrate
provision.  For  prolonged  exercise  >1 hour  in  hot  environ-
mental  conditions,  consuming  fluids  containing  diluted  carbo-
hydrates and electrolytes (<6% carbohydrates and 0.4–0.85 g/L
of  sodium)  may  improve  overall  fluid  consumption  due  to  the
increased  palatability.  Carbohydrate  supplementation  may
include 30–60 g/hour of carbohydrates for exercise >1 hour,125
and up to 90 g/hour for events >2.5 hours.130

Recommendation
 ► The  ingestion  of  a  diluted  glucose  and  electrolyte  drink
(approximately  20–40 g/L  carbohydrate)  can
improve
performance  during  exercise  (>1 hour)  in  a  hot  (30°C)
environment.129

Warm-up and precooling
Athletes undertake preconditioning exercises to ‘warm- up’ before
competing or even before an intense bout of training. While this
activity may increase core temperature and therefore exacerbate
the  thermal  and  cardiovascular  stress  during  prolonged  exer-
cise, an increase in muscle temperature may conversely benefit
muscle contractility.66 Importantly, the effect of warming- up are
both  temperature131  132  and  non- temperature133  134  dependent.
Indeed, a preconditioning activity will begin the metabolic and
circulatory  adjustments135–138  and  may  induce  a  postactivation
potentiation139  along  with  psychologically  preparing  for  the
upcoming  task.140  These  various  effects  have  been  reviewed
with recommendations made elsewhere on the warm- up struc-
ture.66 134

Recommendation
 ► Warm- up  has  both  thermal- depedent  and  non- thermal-
dependent  effects  and  should  therefore  be  implemented
even  in  the  heat.  However,  its  duration  and/or  intensity
should  be  lowered  in  the  heat  to  minimise  the  increase  in
core temperature, especially before prolonged events.

 ► To  minimise  the  increase  in  body  temperatures  before
competing in the heat, athletes can also use cooling methods
(eg, ice vest) while warming- up.

15

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Consensus statement

Clothing
Ultraviolet rays (UVRs) induce a range of skin responses141 and
are the main aetiological agent of skin cancers.142 UVR exposure
can be minimised with appropriate clothing (including head and
neck  protection).143  To  this  end,  sun- protective  clothing  made
from lightweight fabrics that absorb or reflect UVR has become
a standard in outdoor activities. Garments are designed to cover
as  much  skin  as  possible  (eg,  back  of  the  neck)  and  fit  loosely
to  enable  better  convective  heat  exchange  with  the  clothing
microenvironment that sits between the skin surface and inner
clothing layer. Similar to the sun protection factor (SPF) rating
of  sunscreen,  the  ultraviolet  protection  factor  (UPF)  indicates
how many units of UVR are blocked.144 145 A UPF of 25 means
that only 1/25 (4%) of UVR penetrates the fabric, so the higher
the  UPF,  the  greater  the  protection  against  UVR.  Fabrics  with
UPF <15 are not considered protective while UPF >50 provides
minimal additional protection. However, while protecting from
external environmental factors such as UVR, clothing can disrupt
heat transfer from the skin surface and thus impose a thermoreg-
ulatory burden.146–148 Therefore, while staff and officials should
use clothing for sun protection, this strategy needs to be adapted
depending  on  the  metabolic  heat  production  of  the  athlete.
Importantly,  the  main  avenue  for  heat  dissipation  during  heat
exposure  and/or  exercise  is  sweat  evaporation.  It  is  therefore
recommended that clothing should impair sweat evaporation as
little as possible, and the exposed skin area available for evapo-
rative heat loss in athletes is maximised.15 93 For summer sports
where  the  potential  for  sweat  evaporation  may  be  reduced  by
protective equipment, the heat stress risk of non- heat acclimated
athletes can be managed by permitting a progressive period of
heat adaptation with minimal equipment coverage over several
days  before  full  protective  equipment  ensembles  are  worn.74
The common practice of some sports such as using large ‘bibs’
(ie, sleeveless shirts with numbers and logos for identifying and
commercial  purposes)  may  also  have  to  be  adapted  to  provide
the athletes with garments of appropriate fabric, size and fitting
so as not to impair sweat evaporation.

Despite  our  better  understanding  of  sweat  physiology149
and  clothing  requirements,150  it  remains  unclear  how  different
commercially available clothing should be selected depending on
the  prevailing  level  of  heat  stress  (eg,  tropical  vs  desert),  skin
colour, previous exposure/tan and activity.

Recommendations
 ► Officials  and  athletes  with  low  metabolic  heat  production
should  wear  light- coloured,  loose- fitting,  sun- protective
clothing.

 ► Athletes  with  a  higher  metabolic  heat  production  should
wear clothing that does not impair direct sweat evaporation
from the skin.

Sunscreen
Using sunscreen is one of the main preventive strategies to protect
the skin from UVR.142 Sunscreen application recommendations
are  to  apply  ~2 mg  per  cm2  of  protection  to  exposed  skin,151
indicating that adult athletes may need ~15–20 mL of sunscreen
per  application.152  It  has  been  recommended  that  athletes  use
water- based sunscreen (ie, non- greasy) over oil- based sunscreen
that may affect sweating.93 However, there are large differences
in the sweating response to different water- based sunscreens.153
Sunscreen  can  work  as  a  chemical  sun  filter  or  as  a  physical
sunblock.  Chemical  sunscreen  absorbs  into  the  skin  and  then
absorbs UV rays, converts the rays into heat before releasing from

16

the body. The active ingredients in chemical sunscreens include
avobenzone,  octinoxate  and  oxybenzone.145  Physical  sunblock
sits on top of the skin and reflects the sun’s rays. The minerals
titanium dioxide and zinc oxide are the main active ingredients
in  physical  blocks.  When  comparing  an  organic  chemical  sun
filter (oxybenzone) and an inorganic physical sunblock (titanium
dioxide),  both  water- based  with  an  SPF  50,  Aburto- Corona
reported that the latter may impair sweating.153 While the study
design was different from real- world utilisation, athletes should
be encouraged to use sunscreen when necessary given the impor-
tance of sunscreen in preventing skin cancer. Future studies are
needed  to  identify  the  specific  ingredients  in  sunscreens  that
interfere with sweating and their interactions with the thermo-
regulatory response.143

Recommendation
 ► Based on the limited studies in athletes but the well- known
health risk associated with UV exposure, athletes are advised
to  protect  the  exposed  part  of  their  body  using  sunscreen
of SPF ≥25 using a water- based organic chemical sun filter.

Sunglasses
UVR  (<400 nm  wavelength)  is  not  necessary  for  sight  but  is
a  risk  factor  for  cataract  and  macular  degeneration  and  may
damage  the  retina  in  children.154  UVR  can  be  removed  by
wearing  sunglasses  (marked  UV400)  with  a  wraparound  shape
to prevent reflective UVR. Short blue visible light (400–440 nm)
is not essential for sight but is a risk factor for the adult human
retina and should be removed with specific sunglasses for adults
>50 years old.154 Wearing sunglasses when appropriate is recom-
mended on various IOC and IF educational documents.93 Some
contact lenses may also absorb those wavelengths.154

Recommendation
 ► If  allowed  and  safe  in  their  sport,  athletes  should  wear
sunglasses  with  a  minimal  protection  UV400  or  grade  3
when exercising in sunny conditions.

SECTION 3: MEDICAL SERVICE AND MANAGEMENT
CONSIDERATIONS
The reader is referred to the recently published evidence- based
guidelines  on  EHS  management  developed  for  the  Olympic61
and  Paralympic155  Games.  This  section  complements  those
guidelines  by  presenting  some  applied  perspectives  for  their
implementation.

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FoP supervision
Time to reduce the internal body temperature is the key factor
for the success of EHS treatment. Therefore, the FoP medical
plan should facilitate the identification of the athletes suffering
from heat- related illness and their rapid transfer to a medical
station. In the case of endurance sports like race walking, long-
distance running, or triathlon, a course that has been planned
in laps, may reduce the transfer time to the finish line and/or
a  medical  station.  Organisers  should  however  keep  in  mind
that  the  length  of  the  lap  may  be  influenced  by  the  number
of  competitors  (mass  vs  elite  competitions).  For  road  events
spread  along  a  long  distance  (ie,  without  lap),  positioning
medical  stations  along  the  route  may  minimise  the  transfer
time and allow the EHS to be treated immediately (on- site) by
trained practitioners as opposed to transferring the patient to
the nearest hospital. Thus, the race protocol should supersede
the local emergency medical system in case of EHS and should

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be implemented as a common understanding between the FoP
medical and local emergency medical services. Assigning spot-
ters at regular intervals on the competition course to inform
the  triage  medical  manager  of  any  athlete  in  distress  (as  in
the  2019  World  Athletics  Championships)  is  helpful.  For
competitions  with  many  participants  or  competitions  where
the  visibility  is  not  optimal  (eg,  buildings,  tents,  turns,  etc)
spotter towers may be installed to provide a better view of the
finishing  area.  The  spotters  should  be  in  radio  contact  with
the triage manager and the sweep team, and there should be
a well- practised rescue procedure in place for rapid retrieval
of collapsed athletes.

Recommendations
 ► If allowed by the sporting requirements and the number of
competitors,  organising  committees  should  consider  a  lap
course  design  to  simplify  supervision  and  retrieval  of  EHS
athletes  (eg,  such  as  during  the  marathons  of  the  recent
2019 World Athletics Championships and the 2020 Tokyo
Summer Olympic Games).

 ► Spotters (or video surveillance) should be positioned along
the  course  to  identify  and  report  any  heat- related  event
without delay.

Finish area pretriage
Medical  personnel  should  be  deployed  along  the  final  few
hundred  metres  prior  to  the  finish  line.  Ideally,  the  main
medical station should be in the immediate vicinity of the finish
line, with direct and unhindered access to the finish area. The
majority of the event medical staff should be stationed in the
medical station with a FoP team directly observing and with
direct access to the finish area. Where transfer time from the
finish area to the medical station is short, then athlete transfer
can  be  undertaken  using  wheelchairs.  However,  where  the
medical station is not in the immediate vicinity of the finish
area, specifically designated transportation methods (eg, golf
carts) should be available to transfer athletes from the course
to the medical station using predefined routes and FoP points
of entry.

A  pretriage  to  discriminate  between  exhaustion  and  EHS
should  be  commenced  immediately  in  the  finish  area.  It
should be supervised by a medical professional experienced in
the recognition and management of exertional heat illness and
a knowledge of the sport.

Although athletes may want to rest (often seating or lying)
after crossing the finish line, they should be encouraged and
helped  to  walk  immediately  to  avoid  congestion  of  the  area
as this could jeopardise subsequent triage. It is important that
the  finish  area  is  kept  clear  and  the  pretriage  staff  should
strive to rapidly triage and move competitors away from the
finish  area.  Following  a  rapid  clinical  assessment,  athletes
showing  benign  signs  of  exhaustion  should  be  directed  to  a
recovery area, where they can be further observed, rest, rehy-
drate  and  cool  down.  Athletes  with  more  severe  symptoms,
such as central nervous system dysfunction (including severe
difficulty walking and standing), must be transferred immedi-
ately to the medical station and to its heat deck (see further)
for a complete assessment/triage.

Recommendations
 ► The  medical  station  should  be  located  in  and  with  direct

access to the finish area.

Consensus statement

 ► A medical professional (or several based on the number of
participants), with experience of heat- related illness and
a  knowledge  of  the  sport,  should  coordinate  pretriage
in the finish area. Athletes with signs of central nervous
system  dysfunction  should  be  promptly  transported  to
the  medical  station  for  triage  and  further  management
(including  core  temperature  measurement,  neurological
assessment  and  possible  CWI).  Those  with  less  severe
signs of exhaustion should be directed towards the super-
vised recovery area so as not to overburden the medical
station.

Finish area care
All competitors should be offered water, ice or ice towels at
the  finish  area.  Athletes  with  central  nervous  system  distur-
bances should be pretriaged and immediately directed towards
the medical station. They should not be encouraged to drink
until exercise- associated hyponatraemia has been excluded.61
Although  ice  packs  and  ice  towels  may  provide  subjective
benefits  to  the  users,  their  effect  on  both  the  core  tempera-
ture  reduction  and  orthostatic  intolerance  (postfinish  line
collapse)  is  limited  for  the  purpose  of  EHS  treatment.  The
skin surface exposed to cold is too small to trigger a signifi-
cant core temperature decrease in a short period of time.156
For that reason, ice packs and ice towels should be given to
competitors at the finish area for immediate relief from heat
stress, but they do not replace more aggressive cooling such
as  CWI  (aiming  at  cooling  internal  body  temperature  and
enhance central venous return) for athletes suffering EHS.157
Athletes sent to the recovery area should be accompanied
by their entourage or members of the medical team. Walking
(or assisted walking) may support the circulation by activating
the lower leg muscle pump, recirculating pooled blood in the
lower extremities and reducing the incidence of collapse.

Lastly, the finish line area should be kept in order, with no
athletes  lingering  in  the  area  for  longer  than  necessary.  At
this  time,  medical  volunteers  should  actively  look  for  early
recognition  of  EHS,  as  these  athletes  need  to  be  immedi-
ately  transported  to  a  heat  deck  for  prehospital  treatment.
Transfer from the finish line to the medical station is gener-
ally managed by wheelchair with recent data suggesting that
endurance event organisers should plan 1 wheelchair per five
competitors for elite international athletic events in hot and
humid conditions.13

Recommendations
 ► Water,  ice  bag  and  ice  towels  should  be  available  to  all

athletes at the finish line.

 ► Depending on the proximity of the medical venue from the
finish line and the existence of a pathway to allow the reuti-
lisation of the wheelchairs, a demand of up to 1 wheelchair
per  five  competitors  may  be  considered  for  elite  interna-
tional athletic events in hot and humid conditions.

 ► Ensure  that  the  route  from  the  finish  area  to  the  medical
station is wheelchair accessible. Medical stations must have
a ramp for wheelchair accessibility. The wheelchair storage/
waiting area should not obstruct the wheelchair route.
 ► Enough  trained  volunteers  are  required  to  accompany  the
athletes both to the recovery area and to manage wheelchair
transfer  to  the  medical  station  without  depleting  the  FoP
medical staff.

 ► Unless required to stay by the venue medical officer, the FoP
team  should  immediately  return  to  the  FoP  after  handing

17

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Consensus statement

the patient over to the medical station team for further care.
The FoP evacuation, medical station procedures and transfer
between these locations must be clearly described and well-
practiced before the event.

EHS prehospital management
EHS is characterised by extreme hyperthermia (>40.5°C) that
is  accompanied  by  signs  of  central  nervous  system  dysfunc-
tion  (eg,  irrational  behaviour,  altered  consciousness  and  loss
of  consciousness).158  It  is  a  medical  emergency  that  warrants
immediate treatment (ie, whole- body CWI) to ensure survival
and  minimise  the  chance  of  long- lasting  sequela.14  158  159
Therefore,  medical  volunteers  must  be  proficient  in:  (1)  the
transfer of the collapsed athlete from the FoP to heat deck, (2)
rectal temperature assessment, (3) the transfer of the collapsed

athlete  to  whole- body  CWI  bath  and  (4)  determination  of
whether  the  collapsed  athlete  requires  advanced  care  beyond
heat  deck.61  The  medical  team’s  training  should  be  hands- on
and  include  venue  and  event  specific  considerations,  such  as
how the transfer to the heat deck will vary depending on the
location  and  timing  of  the  collapse.  A  practical  guideline  is
presented  in table  1,  and  a  detailed  list  of  equipment  needed
along treatment procedure has been published in the IOC EHS
guidelines.61

While not exclusive to EHS, mass participation events should
have designated hospitals that will admit collapsed athletes who
require  advanced  medical  care  (ie,  acute  cooling  of  those  who
are not transported to heat deck, hypothermic overshoot after
medical  ice  bath,  follow- up  for  EHS  recovery).  Such  partner-
ships will allow the medical organiser to capture the full scope

Table 1  Exertional heat stroke prehospital management on- site preparation and training checklist

Preparation (site visit/ venue assessment)

Training (hands- on training)

During competition

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Daily pre- event meeting
❑ Go through the full medical process from FoP triage to
EHS management
❑ Identify heat deck leader for the day
❑ Identify who is assessing rectal temperature
❑ Identify who is in charge of continuous monitoring vital
signs
❑ Identify who is helping with the transfer (may need
assistance from FOP medical volunteer)
❑ Appropriate triage and communication if heat deck
separated from AMS
❑ Check communication method with the team medical
staff of collapsed athlete
❑ Check on ice storage, provision and how to get more
ice

Ice bath management
❑ Water temperature should be kept between 5°C and
15°C

Deciding heat deck location
❑ Access to FoP
❑ Access to ambulance
❑ Separated and minimal exposure from mix zone
❑ Within or adjacent to the AMS
❑ Access to water and drainage
❑ Access to electricity
❑ Temperature control (availability of air conditioning)
❑ Location of ice stock (preferably within heat deck,
method of ice transfer if outside)

Transfer lines to be tested
❑ From FoP to heat deck (clear, accessible to wheelchair
and stretcher)
❑ From heat deck to ambulance (clear, accessible for
stretcher transfer)
❑ Within heat deck (spacious enough for medical staff to
provide care)

Equipment
❑ Purchase equipment needed to operate heat deck (see
Hosokawa et al. BJSM, 2021.)
❑ Label (number) all rectal thermometers
❑ Rectal thermometer probe≥2 m long (with insertion
mark at 10 cm)
❑ Check time and calibration for all monitors (eg,
thermometer, point- of- care blood analyser)

Education
❑ Aetiology of exertional heat stroke
❑ Distribution of medical policies and procedures to key
medical stakeholders
❑ Environmental heat policies and how it may influence
the event operation and EHS risk

Heat deck operation
❑ Label ice baths with numbers and identify a heat deck
leader that guides medical volunteers to use
❑ Check time to fill (ie, poor water pressure in temporarily
structures) and drain ice baths
❑ Check ice quantities in heat deck and who will collect
more ice
❑ Instruct on cleaning method

Triage
❑ Chain of command from FoP triage to heat deck (radio,
responsibility, transfer of patient)
❑ Chain of command with AMS and within heat deck
❑ Contingency plan for collapsed athlete far away from
AMS and heat deck
❑ Control of wheelchairs, stretchers, and other evacuation
devices

Patient management to know
❑ Familiarise with EHS- specific medical chart
❑ Average cooling pattern (know when to doubt incorrect
measurements)
❑ Discharge criteria (continuous monitoring heat deck,
follow- up care)
❑ Communication with collapsed athlete (reassurance
athletes)
❑ Communication with team medical staff (explanation to
medical staff)

Patient management to practice
❑ Rectal temperature assessment
❑ Handling patient using pole- less mesh stretcher
❑ Transfer of patient to ice bath
❑ Handling of patient while using ice bath
❑ Handling of patient while using ice towels
❑ Taking vitals (eg, blood pressure, heart rate) during EHS
management
❑ Blood sodium assessment using equipment provided
❑ Blood glucose assessment using equipment provided
❑ Preparation of intravenous therapy
Sport- specific considerations
❑ Access to rectal temperature assessment (eg, swimsuit,
protective equipment)
❑ Average size of athletes competing in the event
❑ Identify high risk section, event, situation, etc that can
be observed in respective sports
❑ Review of games rule to identify who has the right to
access athletes first
❑ Extrication of collapsed athlete from unique
environment (eg, water, sand and forest)

AMS, Athlete Medical Station; EHS, exertional heat stroke; FoP, field of play.

18

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Consensus statement

Recommendation
 ► While it is too  early to  take individual decisions  regarding
a potential risk of EHS based on portable technology alone
(eg,  core  temperature)  in  individual  athletes,  and  although
limited by cost and availability for now, IFs/event organisers
may  choose  to  progressively  allow  or  introduce  such  tech-
nology in their event. Whereas this may allow to better char-
acterise  the  overall  risk  associated  with  an  event  itself,  the
individual usage has to be regulated (eg, data ownership, the
timing of feedback and risk of unfair advantage).

SECTION 4: GUIDELINE FOR RISK ANALYSES AND POLICY
DEVELOPMENT BY THE IFS
Most IFs have an extreme weather or heat policy based on the
WBGT  (eg,  football,  tennis,  triathlon),  or  simply  air  (eg,  field
hockey) or water temperature (eg, swimming, triathlon). There
are over 100 existing heat stress indices.162 Most indices include
a  temperature  and  humidity  assessment;  several  also  consider
radiation,  and  some  integrate  human  parameters  such  as  heat
production  (ie,  activity)  and  dissipation  (eg,  clothing).  The
WBGT is currently the most widely used for assessing heat stress
risk in sport- related settings.7 Originally developed for managing
heat stress risk of USA’s military recruits during training activi-
ties, advantages of the WBGT method include a single integrated
value that fully or partially reflects the environmental parame-
ters that determine human heat stress risk. However, it has been
suggested that the WBGT may underestimate the importance of
humidity on athletes with elevated metabolic heat production,7
or that the WBGT may underestimate risk in environments with
low  air  speeds  and  with  high  temperatures  and  low  humidity
where the limit to human heat dissipation is not determined by
the  environment  but  by  the  ability  to  secrete  sweat.163  Thus,
indices  including  physiological  parameters  such  as  markers  of
dehydration164  may  be  more  relevant.  Importantly,  indices
such as the WBGT are often difficult to interpret. Indeed, only
7%  of  the  stadium  athletes  and  23%  of  the  road  race  athletes
surveyed  during  the  2019  Athletics  World  Championships
understood  the  term  WBGT.  Thus,  several  IFs  have  followed
the American College of Sports Medicine guidelines in defining
categories,  habitually  represented  through  a  colour- coded  flag
system.165  However,  while  a  WBGT  of  30.6°C  was  marked
orange by the Tokyo Organising Committee of the Olympic and
Paralympic Games (figure 1), it corresponds to a red flag for the
World  Triathlon  and  is  classified  as  black  by  the  International
Federation  of  Modern  Pentathlon,  making  the  current  systems
confusing during multisports events such as the Olympic Games.
Therefore,  experts  gathered  at  the  meeting  agreed  that  IFs
should henceforth strive to develop sport- specific extreme heat
policies  that  are  efficient,  understandable  and  implementable.
The section below provides the example of a five- step guideline
that  summarises  key  components  that  should  be  considered  to
draft a comprehensive extreme heat policy.

#1: environmental monitoring
Monitoring  environmental  conditions  will  allow  an  IF  to  esti-
mate the environmental risk for their athletes, similar to the heat
stress monitoring programme that has been implemented by the
International Volleyball Federation (beach) for all international
competitions  since  2009.65  166  Monitoring  the  environmental
conditions is also the first step to inform the implementation of a
heat stress policy. However, while all components of any indices
(eg, natural wet- bulb temperature, black globe temperature and
dry- bulb temperature for WBGT) must be physically measured,

19

Figure 4  Real- time monitoring of athlete’s thermal responses during
the 2020 Tokyo Summer Olympic Games. Panel A: dashboard accessible
online allowing to follow an athlete during a race walk event (the route
consisted of 1 km loops at Odori Park, Sapporo). Panel B: example of
data recorded during the male 10 000 m and being visualised in real
time (Olympic stadium).

of medical services rendered and medical outcomes from partic-
ipation in the event.

Recommendations
 ► A  sporting  event  with  a  foreseeable  risk  of  EHS  should
prepare  a  designated  treatment  area  (eg,  heat  deck),
including appropriately trained personnel, set- up and equip-
ment  for  rectal  temperature  assessment  and  rapid  cooling
(eg, medical ice baths).

 ► Medical  volunteers  must  receive  a  hands- on,  pre- event
training session on EHS recognition, assessment, treatment
and post- treatment management.

Athlete monitoring
As  mentioned  previously,  several  IFs  have  heat  policies
allowing them to alter an event in case of heat stress. However,
the decision is currently informed by environmental parame-
ters. Obtaining real- time athlete data would better inform the
decision makers on how the athletes are currently coping with
the  environmental  conditions.  The  technology  in  this  area
is  rapidly  developing,160  with  several  studies  having  already
recorded  thermal  responses  during  world  championship
events.9 32 The first real- time monitoring occurred during the
2020 Summer Olympic Games (figure 4). Knowing an athlete’s
physiological status however, raises an ethical dilemma,161 as
there  is  no  ethical  or  legal  grounds  for  making  a  decision  to
withdraw an athlete from a race against his or her will. Real-
time physiological monitoring may however inform the LOC
and/or IF at the organisational level to determine if an event
should be altered when participants appear to have difficulties
coping with the extreme conditions.

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Consensus statement

they  are  often  estimated  using  only  temperature  and  humidity
with  assumptions  on  cloud  cover  and  wind  speed.162  All  vari-
ables required to  calculate the  chosen  heat stress  index should
be  physically  measured  (using  the  recommendations  provided
previously) and not derived or estimated from other measures.

#2: define physiological/physical parameters
Not  all  sports  present  the  same  thermoregulation  challenges
due to different heat production (ie, intensity and duration) and
dissipation (eg, clothing, air velocity). For example, the relatively
high velocity in cycling may allow for air movement around the
rider and favour the convective heat loss.71 167 With an ambient
temperature of 35°C and relative humidity of 50%, the maximal
convective and evaporative cooling capacity of a cyclist at 40 km/
hour has been estimated to be 43% higher than a runner at 20 km/
hour and 60% higher at 50 km/hour.168 However, such convec-
tive advantage will disappear during up- hill cycling, where the
racing speed is lower, or when the air temperature is higher than
the  skin  temperature.  Risk  thresholds  should  also  be  adjusted
according to the required clothing and protective equipment by
the rule of the sport (and the possibility to adapt them).

In addition to the characteristics of the sport (eg, swimming vs
cycling vs running vs sailing) and the competition (eg, distance,
course), the characteristics of the athletes should also be consid-
ered  (eg,  age  and  acclimation  status).  If  the  chosen  heat  stress
index allows, parameters that broadly define the athlete’s ther-
moregulatory demand should be integrated when interpretating
the index. For example, heat acclimation status profoundly alters
the  boundary  between  compensable  and  uncompensable  heat
stress secondary to modification in maximum skin wettedness.169
Similarly, injuries such as skin burns, or spinal cord damage, lead
to  significant  physiological  impairments  to  sweating.170  171  If
physical  parameters  such  as  the  surface  area- to- mass  ratio  are
distinctly different along with competitors morphology (eg, chil-
dren vs adults), parameters should be adjusted accordingly.172

#3: define the acceptable level of heat stress risk
The acceptable risk is specific to the population that the policy
is designed to protect. Elite- level professional competitors may
expect to tolerate (and be appropriately conditioned for) higher
levels of heat stress than amateur community- based competitors
playing the same sport. Seasonal changes (eg, early summer) or
unseasonal weather (eg, heat wave) present additional risks. The
readiness  of  the  organising  committee  and  medical  services  in
managing  potential  cases  of  exertional  heat  illness  should  also
be considered (eg, a competition without a proper heat deck61
cannot afford the same level of risk as a competition where exer-
tional heat illness can be safely managed).

#4: generate a risk assessment format that is easy to
understand and implement
Even the most evidence- based heat stress risk assessment will be
limited  in  its  effectiveness  if  the  output  is  not  easily  compre-
hended  or  actionable  by  stakeholders  such  as  athletes,  physi-
cians,  coaches  and  event  organisers.  For  example,  raw  WBGT
values are reported with °C units and can be misleading because
they are often lower than air temperature (figure 1). Therefore,
outputs  from  any  heat  stress  index  should  be  scaled  appropri-
ately  in  a  format  that  is  accessible  and  familiar.  A  traffic  light
(red, amber and green) system or a 1–5 scale (figure 1) is easily
understandable as it is used in many circumstances of everyday
life from environmental hazards (eg, fire) to rating systems (eg,
ridesharing, movies, hotels etc).

20

#5: incorporate evidence-based heat stress mitigation
strategies that are feasible and implementable
Associated with each risk threshold defined by the scale selected
in  #4,  recommendations  can  be  triggered  for  implementing  a
strategy  that  serves  to  reduce  physiological  heat  strain  (online
supplemental appendix 2). These strategies are informed by the
scientific evidence and may range from recommendations to the
athletes  to  providing  extra  services  (eg,  hydration  station  and
cooling bath), modifying the rules of the sport (eg, additional/
longer break) and even postponing the event. Equally important,
these strategies must be compatible with the setting, in terms of
available resources and opportunities for their use in the context
of the standard format of the specific sport without unduly inter-
fering with play.

Other methods and verification
The previous five steps are based on a thermophysiological anal-
ysis of the sport. This approach was implemented to develop an
extreme heat policy for the Australian Open Grand Slam Tennis
tournament  as  detailed  in  online  supplemental  appendix  2.  It
differs from the common ‘sequence of prevention’ of sports inju-
ries that aim to establish first the extent of the problem, then the
aetiology and mechanism of the injury, then introduce preventive
measures  before  assessing  their  effectiveness  (by  repeating  the
first step).173 Irrespective of the method employed, it is recom-
mended  that  IFs  work  towards  developing  comprehensive  heat
stress guidelines that reflect the risks specific to their sports and
ensure consistency across competitions within one sport. It is also
recommended to assess the effectiveness of the heat policy and
to modify it accordingly if required. Lastly, it is recommended to
use a 1–5 scale for consistency and clarity in reporting the level of
risk and the associated countermeasure (figure 5).

LIMITS, PERSPECTIVES AND CONCLUSION
Limitations
Body  temperature  has  been  used  as  a  health  indicator  for
millennia  and  is  still  one  of  the  first  vital  signs  measured.  The
research on the effect of heat on healthy active humans is however
much more limited and historically driven by the requirements
of  the  mining  industry  and  the  military.  While  there  has  been
extensive research on exercising in the heat in recent years, most
knowledge is derived from laboratory studies using recreational
athletes. Therefore, there is a need for research in elite athletes,
practising  their  sports  outdoors.  This  need  is  further  exacer-
bated by the ethical concerns associated with the technological
developments that allow the monitoring of athletes in real time
(figure 4).

It  was  decided  for  these  recommendations  to  focus  on  the
athlete, their entourage and the event organisers. We have not
included spectators in these recommendations, but event organ-
isers are encouraged to seek advice from public health experts
and  coordinate  their  effort  with  the  local  health  services.  In
some instances, the spectator’s protection is also directly related
to  the  event  organiser.  For  example,  the  IOC  working  group
agreed  with  the  Tokyo  Organising  Committee  of  the  Olympic
and Paralympic Games to allow spectators to bring one plastic
bottle  filled  with  water  through  security  (up  to  750 mL  to
accommodate the 21 oz/600 mL sport bottles). Such negotiation
involved all concerned stakeholders (eg, security, sponsors) and
was carried out 2 years before the event.

Perspectives
The  current  document  covers  a  range  of  topics.  For  some  of
them  (eg,  acclimation),  there  was  already  extensive  referenced

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Consensus statement

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Date: dd/mm/yy
Time: 9h00
Venue: Beach arena

Date: dd/mm/yy
Time: 17h00
Venue: Olympic stadium

Date: dd/mm/yy
Time: 9h00
Venue: Triathlon, Transition area

Heat stress rating = 2.4

Heat stress rating = 3.8

Heat stress rating = 4.6

3
(High)

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4
(Very high)

3
(High)

2
(Moderate)

4
(Very high)

3
(High)

2
(Moderate)

4
(Very high)

1
(Low)

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(Low)

5
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(Low)

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No specific restriction to Beach-volleyball
competitons

Modification in place for Athletics competitons:

Modification in place for the Triathlon:

• Water feeding table on the 5,000m

• The Standard distance will be reduced to a

Sprint distance

Date: dd/mm/yy
Time: 14h30
Venue: Tennis park, central court

Date: dd/mm/yy
Time: 16h00
Venue: Tennis park, central court

Heat stress rating = 4.2

Heat stress rating = 5.1

3
(High)

2
(Moderate)

4
(Very high)

3
(High)

2
(Moderate)

4
(Very high)

1
(Low)

5
(Extreme)

1
(Low)

5
(Extreme)

Modification in place for the Tennis tournament:

Modification in place for the Tennis tournament:

• 10 min break between the second and third

• Suspension of play for ongoing matches at the

sets (when applicable)

end of the set

• Change-over time will be 90 sec.

• No other match to start

Figure 5  Example of a heat stress scale that could be adapted and used across sports. The scale uses a common 1–5 colour- coded rating with
the exact value indicated. The current preventive measures to action are openly listed to inform athletes, organisers, medical services and other
stakeholders. The listed modifications are non- contractual examples; each IF is in charge of their heat policies.

literature  available.  For  other  topics  (eg,  mist,  shading),  more
research  is  required  that  replicates  the  conditions  athletes
experience.

IFs  and  event  organisers  are  also  encouraged  to  conduct
systematic  monitoring  of  the  environmental  conditions  and
health  hazards  during  their  event  to  establish  an  epidemiolog-
ical database and inform future policies. Along these lines, it is
important to understand how widespread heat decks are used,
their  effectiveness  and  the  problems  encountered.  With  this
information,  it  will  be  possible  to  review  and  modify  the  heat
deck recommendations based on clinical data in the future.

In addition, while research and scientific publications may be
considered the two first steps of risk mitigation, it is also neces-
sary to communicate with the different stakeholders using their
own  language,  including  video  and  social  media  for  athletes,
policies for IFs and organisers, medical workshops for clinicians,
etc. In the case of the Tokyo Summer Olympic Games, the IOC
developed  educational  material  based  on  the  previous  leaflet
from  the  Union  Cycliste  Internationale  and  World  Athletics,
using  athlete  role  models.  For  local  medical  volunteers,  the
Tokyo  Organising  Committee  of  the  Olympic  and  Paralympic
Games hosted specific training on exertional heat illness prehos-
pital management.

CONCLUSION
Heat- related  issues  are  one  of  the  main  life- threatening  events
for athletes, commonly summarised as the 3 Cs (cardiac, cere-
bral/concussion and climate) or the 3 Hs (heart, head and heat).
Each of these life- threatenning conditions has their own interna-
tionally agreed management protocols that should be integrated
into the mandatory training for all FoP medical teams. However,
while most team physicians are well aware of the management
of  cardiac174  and  concussion175  issues  in  athletes,  several  are
not  familiar  with  the  specific  prehospital  management  of  EHS
for  athletes61  and  para- athletes.155  Thus,  specific  training  is

warranted for medical personnel covering events in hot ambient
conditions. The appropriate management of EHS (ie, algorithm
and facilities) allow improved recovery and survival.14

As for other health concerns, the athlete is the primary actor
for  their  own  health.  Thus,  athletes  and  their  entourage  have
the  responsibility  to  properly  prepare  for  the  competition
environmental  conditions,  including,  but  not  limited  to,  heat-
acclimation, hydration and health status.

Lastly, protecting the athlete’s integrity when competing in the
heat is also the responsibility of the IF and the event organiser.
They need to facilitate both mitigation and treatment measures,
as  well  as  adapt  the  event  to  the  conditions.  The  governing
bodies should make the athlete and their entourage fully aware
of the environmental conditions and the counter measures that
have  been  developed  in  response  through,  for  example,  the
venue  medical plan  detailing  the  different  scenarios  and  a  1–5
colour- coded  universal  heat  stress  scale  clearly  illustrating  the
current measures in actions (figure 5).

Author affiliations
1Research and Scientific Support Department, Aspetar Orthopaedic and Sports
Medicine Hospital, Doha, Ad Dawhah, Qatar
2Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan
3Health and Science Department, World Athletics, Monaco
4Union Cycliste Internationale (UCI), Aigle, Switzerland
5Korey Stringer Institiute, Department of Kinesiology, University of Connecticut,
Storrs, Connecticut, USA
6Department of Geography, University of Georgia, Athens, Georgia, USA
7Heat and Health Research Incubator, Faculty of Medicine and Health, The University
of Sydney, Camperdown, New South Wales, Australia
8Medical Department, Federation Internationale de Football Association, Zurich,
Switzerland
9Medical Committee, World Triathlon (WT), Lausanne, Switzerland
10Hamilton, Stockholm, Sweden
11World Sailing, London, UK
12School of Sport and Health Sciences, University of Brighton, Eastbourne, UK
13Institute for Sports Medicine, Alpine Medicine & Health Tourism (ISAG), UMIT Tirol
– Private University for Health Sciences and technology, Hall, Austria

21

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Racinais S, et al. Br J Sports Med 2023;57:8–25. doi:10.1136/bjsports-2022-105942

Consensus statement

14University Hospital/Tirol Kliniken, Innsbruck, Austria
15Sport- und Rehabilitationsmedizin, Universitat Ulm, Ulm, Germany
16Marubeni Health Promotion Center, Tokyo, Japan
17International Olympic Committee Medical and Scientific Games Group, Pinner, UK
18Medical and Scientific Department, International Olympic Committee, Lausanne,
Switzerland
19International Olympic Committee, Lausanne, Switzerland

Twitter Sebastien Racinais @ephysiol, Ollie Jay @ollie_jay13 and Andrew Massey
@andy_massey

Acknowledgements  The authors thank the IOC medical and scientific
commission, the IOC Medical and Scientific Commission Games Group and the
Association of Summer Olympic International Federations for the reach discussions
preceding this work.

Contributors  All authors were part of the consensus meeting. All authors
participated to the two rounds of Delphi evaluation. All authors contributed to write
one or more sections and approved the final manuscript. The following authors were
part of the ’IOC Adverse Weather Impact expert working Group for the Olympic
Games Tokyo 2020’: SR (chair), YH, TA, SB, DJC, AJG, YP, WS, FY, DZ and RB. The
following authors were part of the Tokyo Organising Committee of the Olympic and
Paralympic Games: YH, TA (CMO) and FY. The following authors were part of the IOC
Medical and Scientific Commission Games Group: SR, TA, MM, DZ, LE and RB. The
following authors were medical directors for an international federation: SB, XB, AM,
SM, MM, NN and JMS.

Funding  The consensus meeting was funded by the IOC.

Competing interests  None declared.

Patient consent for publication  Not applicable.

Ethics approval  Not applicable.

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Provenance and peer review  Not commissioned; externally peer reviewed.

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Supplemental material  This content has been supplied by the author(s).
It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not
have been peer- reviewed. Any opinions or recommendations discussed are
solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all
liability and responsibility arising from any reliance placed on the content.
Where the content includes any translated material, BMJ does not warrant the
accuracy and reliability of the translations (including but not limited to local
regulations, clinical guidelines, terminology, drug names and drug dosages), and
is not responsible for any error and/or omissions arising from translation and
adaptation or otherwise.

Open access  This is an open access article distributed in accordance with the
Creative Commons Attribution Non Commercial (CC BY- NC 4.0) license, which
permits others to distribute, remix, adapt, build upon this work non- commercially,
and license their derivative works on different terms, provided the original work is
properly cited, appropriate credit is given, any changes made indicated, and the use
is non- commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

ORCID iDs
Sebastien Racinais http://orcid.org/0000-0003-0348-4744
Yuri Hosokawa http://orcid.org/0000-0001-9138-5361
Takao Akama http://orcid.org/0000-0002-3937-2448
Stephane Bermon http://orcid.org/0000-0002-9529-2901
Douglas J Casa http://orcid.org/0000-0002-8858-2636
Andrew Grundstein http://orcid.org/0000-0002-0574-6253
Ollie Jay http://orcid.org/0000-0002-6076-6337
Andrew Massey http://orcid.org/0000-0002-8253-932X
Yannis P Pitsiladis http://orcid.org/0000-0001-6210-2449
Wolfgang Schobersberger http://orcid.org/0000-0002-5657-0307
Fumihiro Yamasawa http://orcid.org/0000-0001-6315-8479
David Anthony Zideman http://orcid.org/0000-0002-7111-6161

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