Uphill Walking as Exercise for COPD Patients
Condition: Chronic Obstructive Pulmonary Disease
MeSH terms: Lung Diseases; Lung Diseases, Obstructive; Pulmonary Disease, Chronic Obstructive
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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
      60% 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 60% 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.
    

Intervention name(s): walking on incline or walking at increasing speed
Intervention type(s): Other
Intervention description(s): Subjects will be prepared for data collection by wearing a form-fitting suit (i.e., wrestling singlet) and obtaining height and body weight. Retro-reflective markers will be placed bilaterally on anatomical locations of the feet, legs, and hips.
be outfitted with the portable metabolic cart and oximeter as in the previous visit. One of two treadmill trials will be performed: 1) at the speed and 2) at the slope +speed determined in the previous visit. Trial order will be randomized among subjects and across visits 3 & 4. For each trial, subjects will be asked to walk on a treadmill for up to 6 minutes. Speed or slope will be increased every 30 seconds and they will be asked to walk for one minute at that speed or
Intervention model: Single Group Assignment
Intervention model description: Cross-sectional design
Masking: None (Open Label)
Primary purpose: Supportive Care
Keywords: pulmonary rehabilitation