Assessing the Efficacy of Passive Exoskeletons for Construction Work: Lab-Based Study
Assessing the Efficacy of Passive Exoskeletons for Construction Work: Lab-Based Study
This project aims to assess the effectiveness and acceptability of four types of commercial
 Back support exoskeletons (BSEs) for concrete work tasks. BSEs are external wearable devices
 designed to reduce physical demands on the back by providing assistive moments to body joints
 to support muscles. There is considerable evidence to suggest such exoskeletons reduce the
 risks of back injuries for workers performing repetitive tasks. However, since the effects of
 using BSEs in concrete work tasks are still unknown, evidence-based information regarding
 effectiveness, productivity impact, and safety risks is required to help industries adopt
 BSEs as an ergonomic intervention.
The experimental protocol will require approximately 3 hours of the participant's time. It
 will be comprised of six stages:

 Stage I: Body Discomfort and Handedness Questionnaires First, the research team will
 administer an interview questionnaire to the participant to obtain information on
 participants' body pain/discomfort level and to determine the participant's hand dominance
 using the Edinburgh Handedness Inventory.

 Stage II: Anthropometric body measurements and strength testing Several anthropometric body
 dimensions will be measured in the standing upright position using a standard tape measure
 and anthropometer. Body measurements will include standing height, shoulder height, waist to
 floor height, leg length, knee height, upper and lower arm length, foot length, and inter
 shoulder distance. Study participants' body weight will be measured using a standard weighing
 scale. Maximum power grip strength on both hands will be measured for 3 trials using a
 standard hand-held grip dynamometer.

 Stage III: Fitting BSEs Four types of commercial BSEs (backX, Laevo 2, FLx ErgoSkeleton, V22
 ErgoSkeleton) will be introduced to participants. Following manufacturers' instructions,
 participants will be allowed to test each device, fit the device to their body for comfort by
 using adjustable features (e.g., straps).

 Stage IV: Optical motion capture marker, wearable inertial sensors, and surface
 electromyography (sEMG) sensor placement A commercial motion-capture system (Qualisys AB,
 Kvarnbergsgatan, Göteborg, Sweden) will be used to monitor and analyze body segment motion
 trajectories in a three-dimensional space. Several optical markers will be placed on
 anatomical landmarks of study participants including the head, shoulders, arms, hands, back,
 pelvis, legs, and feet. Hypo-allergenic double-sided tape will be used to attach the optical
 markers to the anatomical landmarks. Wearable inertial sensors will be attached using
 hypoallergenic double-sided tape at the low-back near the waist (S1), upper back (T6),
 sternum, upper arm (R, L), lower arm (R, L), thigh (R, L), and shank (R, L). Eight sEMG
 sensors will be placed on Descending Trapezius (TRP), Anterior Deltoid (AD), Iliocostalis
 Lumborum (ILL), Rectus Abdominis (RA), External Oblique (EO), Cervical Erector Spinae (CES),
 Latissimus Dorsi (LD), and Vastus Lateralis (VL) to measure muscle activation level while
 performing simulated work tasks, which are described in Stage VI.

 Stage V: Maximum Voluntary Contraction (MVC) measurement for muscle activation While
 performing work tasks, muscle activation level varies between muscles and between subjects. A
 common way is to normalize myoelectric activities of each muscle for every participant by
 measuring isometric Maximal Voluntary Contraction (MVC). In this study, the investigators
 will measure 11 MVCs before the start of actual work tasks. Our MVC tests will be based on a
 study of trunk muscles. Before the MVC measurement, participants will be asked to warm up by
 5 stretch exercises: (a) Stand upright with his feet shoulder-width apart. Place his hands on
 his buttocks for support. Look upwards and slowly lean backward. Keep his legs sturdy. (b)
 Stand upright with his feet shoulder-width apart. Place one hand on his buttocks for support.
 Look up and slowly lean backward. Reach over with his opposite hand. Rotate the upper body at
 the waist. (c) Kneel on one foot. Place his hands on his hips. Push hips forward. If
 necessary, hold on to something to keep balance. (d) Stand upright with his feet
 shoulder-width apart. Cross his arms and place his hands on shoulders. Slowly rotate his
 shoulders to one side. To increase the intensity of this stretch, use his hands to help
 rotate sideways. (e) Kneel on all fours. Support himself with one hand and reach towards his
 ankle with the other. Keep his back parallel to the ground. Keep the back straight, parallel
 to the ground, and his thigh in a vertical position. Distribute his weight evenly on both
 hands and knees. After the warm-up, the MVC testing will be performed, which includes (1)
 upper trunk flexion: subject will be in a sit-up posture positioned on a bench with the legs
 bent and feet strapped down with a belt. He then will attempt to flex the upper trunk in the
 sagittal plane while her thorax will be manually braced by the experimenter; (2) upper trunk
 twisting (R and L): In the same sitting supported position, the subject will attempt to twist
 the upper trunk in the horizontal plane while his thorax will be manually braced by the
 experimenter;(3) lower trunk flexion: subject will attempt to flex the lower trunk in the
 sagittal plane while he will be in a supine laying position, but with knees and hips both
 bent to approximately 90 degrees. His thorax will be strapped down with a belt and his legs
 will be manually braced by the experimenter; (4) lower trunk twisting (R and L): In the same
 lying and supported position, the subject will attempt to twist the lower trunk in the
 horizontal plane while his legs will be manually braced by the experimenter;(5) upper trunk
 bending (R and L): subject will attempt to side bend the upper trunk in the frontal plane
 while he will be in a side-lying position, with the knees bent and strapped with a belt, and
 thorax and arms will be manually braced by the experimenter; (6) lower trunk bending: subject
 will maintain a right and left side bridge position while maximally resisted downward
 pressure on the pelvis will be applied by the experimenter;(7) upper trunk extension: subject
 will be strapped in a prone position, with the torso horizontally cantilevered over the end
 of the bench (Biering-Sorensen position). He will then attempt to extend the upper trunk in
 the sagittal plane and retract the shoulders (squeezing the scapulae together) while manual
 resistance will be applied on the shoulders by the experimenter; (8) lower trunk extension:
 subject will attempt to extend the lower trunk and the hips against manual resistance when in
 a prone position, with the torso on the bench and the legs horizontally cantilevered over the
 end of the bench; (9) shoulder rotation and adduction (R and L): subject will attempt to
 adduct and internally rotate the shoulder against manual resistance with the shoulder
 abducted and elbow flexed, both to 90 degrees. In addition, two unresisted maximal abdominal
 contractions will be performed in standing; (10) maximal effort abdominal hollowing: subject
 will attempt to maximally activate the deep abdominal muscles while drawing in the lower
 abdomen; (11) maximal effort abdominal bracing: subject will attempt to maximally activate
 all the abdominal wall without any change in the position of the muscles. In all MVC testing,
 participants will be asked to exert their maximum force at a static posture (instructions
 will be given by our researcher) for every five seconds. For the first two seconds, they will
 be asked to ramp up to their maximum and maintain the force for the next three seconds. MVCs
 will be tested at least two times for each muscle group.

 Stage VI: Data collection in simulated construction work tasks Postural data will be recorded
 from participants while performing six simulated concrete work tasks (i.e., shoveling,
 framing, carrying and lifting of construction materials, hammering, and tying rebars) at
 different intensities. The material they will be lifting, carrying, shoveling, and holding
 will not go over the safety limit of 30 lbs, as stated by NIOSH. Participants will perform
 the tasks with vs. without wearing different BSEs. Task trials will be video recorded for
 visual correspondence when analyzing motion capture and inertial sensor data. Participants
 will be given two minutes rest break between tasks and thirty seconds rest break between
 trials. The order of task conditions within each work task will be randomized.

 -  Task 1: Shoveling and moving construction material from location A to B. Distance
 between A and B will be set to 0.5m, both located at the ground level. Participants will
 be asked to shovel construction materials with three different weights (i.e., dirt,
 cement, and gravel). Participants will be asked to shovel at a high-frequency rate (15
 scoops per minute).

 -  Task 2: Framing 30" wall using a power screwdriver. The frame will be placed on the
 floor, versus an elevated surface (28" height). Participants will be asked to use a
 power screwdriver to drive a screw into and out of the frame.

 -  Task 3: Carrying construction materials of different weights (i.e., wood frames and
 pipes) for up to 10 meters in each trial. The maximum weight of the carried materials
 will not exceed 30 lbs.

 -  Task 4: Lifting construction materials of different weights. The same materials will be
 used as the carrying task.

 -  Task 5: Pounding a punching bag located in the ground vs. 18 inches high vs. 36 inches
 high using a sledgehammer of different weights (i.e., 0, 6, 12, 16, and 20 lbs.).

 -  Task 6: Tying rebar in a framed grid located on different height levels (i.e., 0", 50").

 The tasks and intensity levels were selected to be diverse yet reproducible (in terms of body
 postures) and resemble common tasks encountered in concrete work tasks.

 Participants will be asked to answer questionnaires asking their experience, usability, and
 acceptability on each exoskeleton after they complete each work task.

 The data collection process will end with removing optical markers and wearable sensors.
 Participants will be offered a rest break and refreshment if needed and followed by
 compensation and completing the payment form.
Inclusion Criteria:

 -  Be at least 18 years old.

 -  Be able to walk and/or lift heavy objects without pain/discomfort.

 Exclusion Criteria:

 -  Have prior back/neck injuries or chronic pain in the last 6 months.

 -  Have a pacemakers.

 -  Have breast implants.

 -  Have removed the axillary lymph nodes.

 -  Pregnant women.

 -  Using blood thinning medications.

 -  Participants must consult a physician prior to participating this study if any of the
 following occurred before or during use: Inguinal hernia, hernia, knee injury hip/knee
 prosthesis, hyperextended knee, recent surgery, skin disease/injury, scars,
 inflammation, skin reddening.