Length of exercise training in COPD: a single-subject design

Abstract

Backgroud: The minimum duration of exercise training in patients with Chronic Obstructive Pulmonary Disease (COPD) is still discussed.

Objectives:  To document, over time, the effects of a lower-limb endurance training program in a patient with COPD, evaluating when changes in the exercise capacity initiate and if these changes stabilize during the intervention period.

Methods: A 73-year-old male COPD patient (FEV₁ 0.92 L) performed three 30-minute training sessions per week, during 12 weeks, at 70% of peak work rate. A metabolic analyzer system was used to evaluate the participant, at regular intervals, during an incremental, symptom-limited cycle ergometer exercise test. Peak and isowork exercise variables were studied. Data were analyzed with visual analysis, associated with Kappa statistic, two-standard deviation band, celebration line and regression analysis. Significance was accepted at (p<0.05).

Results: Peak exercise variables as work rate, carbon dioxide output and ventilation (VE) increased significantly. At a same workload, oxygen uptake (VO₂), (VE), perceived exertion and heart rate decreased and peripheral oxygen saturation (SpO₂) increased significantly. Changes in exercise capacity verified by VE,VO₂, perceived exertion and SpO₂, at isowork condition, were observed in the fourth week of training. Regression analysis showed that VO₂and respiratory frequency decreased significantly in the course of intervention, while tidal volume and SpO₂ increased during this phase.

Conclusions: The participant improved his exercise tolerance after the training program. Changes in exercise capacity initiated in the fourth week of intervention and continued until the end of the training program.