Uphill Walking as Exercise for COPD Patients
Uphill Walking as Exercise for COPD Patients
This study is designed to provide preliminary information regarding how to improve pulmonary
 rehabilitation for persons with chronic obstructive pulmonary disease (COPD). Pulmonary
 rehabilitation is an exercise program for COPD patients that is recommended and benefits
 some, but not all, patients. The question being studied in this trial is whether walking on
 an incline might be better than walking on faster on a flat surface in training muscles so
 that patients might be less short of breath with exercise.
Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality and
 presents an important healthcare problem, especially for Veterans. Prevalence of COPD in the
 Veteran population ranges from 33%-43%, a higher prevalence than among the general population
 of the United States. COPD patients experience diminished exercise capacity. A significant
 portion of this limitation in exercise capacity is due to dynamic hyperinflation and dyspnea.
 Humans demonstrate a coupled relationship between walking and breathing. The investigators'
 preliminary data indicates that patients with COPD demonstrate an abnormal coupling pattern
 compared to those without COPD, using one stride for one breath, even at speeds outside of
 their self-selected walking pace. Current pulmonary rehabilitation relies on increasing
 intensity of exercise through accelerated walking. Based on coupling patterns in patients
 with COPD, increasing speed leads to an increase in respiratory rate, dynamic hyperinflation,
 and dyspnea, thus limiting exercise time. The goal of this proposed project is to
 investigate, in Veteran COPD patients, the effect of walking faster vs. walking on a slope on
 dynamic hyperinflation and dyspnea, oxygen uptake and dead space, and walking and breathing
 coupling. The investigators hypothesize that walking on a slope will alter breathing and
 walking coupling, lower respiratory rates, and reduce dynamic hyperinflation and associated
 dyspnea. The investigators predict that walking on a slope will permit an increase in oxygen
 uptake and a decrease in dead space in patients with COPD as compared to accelerated walking
 speeds. These hypotheses will be tested through three aims: 1) Identify differences in
 dynamic hyperinflation and dyspnea; 2) Compare differences in respiratory rate, oxygen
 uptake, and lung dead space; 3) Determine the complexity of walking and breathing coupling
 ratios. In this cross-sectional study, Veterans with COPD will be recruited and screened
 using a cardiopulmonary exercise test. A total of 25 eligible Veterans will be enrolled
 through stratified sampling of disease severity. The time course of work rate will be
 calculated from the cardiopulmonary exercise test. The speed and slope that corresponds to
 70%-80% of peak work rate will be used. An additional constant work rate test will be given
 using increases in speed with a level treadmill to determine the speed that elicits oxygen
 uptake comparable to the sloped walking test. Subjects will be asked to perform two
 experimental trials (walking faster vs. walking on a slope) at 70%-80% peak work rate.
 Measures of dynamic hyperinflation, dyspnea, oxygen uptake, dead space, and coupling will be
 recorded during all walking trials. Possible covariates will also be collected. The
 investigators anticipate that dynamic hyperinflation and dyspnea will be reduced in patients
 with COPD due to slower walking and slower respiratory rates during sloped walking as
 compared to faster level walking. It is expected that this will be influenced by the
 complexity in breathing and walking coupling ratios. The investigators' multidisciplinary
 team will provide combined expertise from several disciplines and is uniquely qualified to
 complete the aims proposed. Results from this feasibility and acceptability study will set
 the stage for a rigorous, well-powered, full Merit award outcome study evaluating the
 effectiveness of a slope-based training regimen as part of rehabilitation.
Inclusion Criteria:

 -  Veterans from all sex/gender, race, and ethnicity will be recruited

 -  All subjects will undergo post-bronchodilator spirometry and be clinically stable

 -  All subjects must have documented FEV1/FVC ratio of <0.7, and between 30% to 80% FEV1%
 predicted

 -  If subjects have non-qualifying spirometry, they will not be screened further

 -  Subjects with qualifying spirometry will be screened further

 -  Potential subjects must have a BMI of less than 35 kg/m2 and must be free from
 co-morbidities that may affect walking patterns

 -  e.g., peripheral arterial disease, diabetes, low back pain

 Exclusion Criteria:

 -  Confounding effects such as neurological, musculoskeletal, or metabolic disease

 -  Subjects taking medications that alter mood or metabolic demand will be excluded

 -  All potential subjects must be cleared for participation by a physician after
 undergoing a cardiopulmonary exercise test