Physiological Response to Moderate Exercise Workloads in a Pulmonary Rehabilitation Program in Patients With Airflow Obstruction: Discussion

Physiological Response to Moderate Exercise Workloads in a Pulmonary Rehabilitation Program in Patients With Airflow Obstruction: DiscussionThere is considerable evidence (approaching 40 studies) that documents the benefits of exercise regimens in pulmonary rehabilitation strategies. However, there are only a minority of exercise programs that have been specifically designed to elicit as primary outcome measures the physiologic changes within the exercising muscles and other organ systems. The present training program design differed importantly from other programs … in two respects. First, it featured only two exercise training sessions per week; second, it incorporated multimodality lower limb exercises. It may be argued that the variety of different exercises incorporated into the present program renders the interpretation of training improvements to be perhaps more problematic in contrast to those programs in which the training interventions were solely restricted to cycle ergometer activities. However, we believe that the diversity of the training modalities selected were more realistic and functionally more relevant to the daily activities of our study population.
Although the duration of this entire program (12 weeks) and the duration of the individual exercise training sessions (60 min) were well within the recommendations for exercise training programs, this study is notable not only for the number of patients studied in comparison to other recently published data, in which physiologic variables were used as primary outcome measures to assess the effects of training, but also by the wide spectrum of airflow limitation encompassed within the large study population.
The target training intensity of bicycle exercise in this program (50% of the baseline peak WR) was lower than comparative studies that featured target training intensities equivalent to 80% of the baseline peak WR. However, it has been previously shown that training intensity is often difficult to interpret because actual training loads may differ from the training prescription. other

The majority of patients in the current study were able to exceed their initial training prescription by up to 25%. Nevertheless, the relatively moderate training frequency and intensity employed in the present program possibly explain why improvements in exercise tolerance (peak WR by 18% and peak V02 by 5%) were smaller than those previously reported by Casaburi et al (increased peak WR and V02 by 35% and 16%, respectively), although patient demographics and training schedules were not directly comparable. In relation to other comparative studies,– training improvements seen in this study were greater than those seen in a low WR (50% peak WR) and moderately obstructed training cohort, and were comparable to the improvements documented by Maltais et al (increases in peak WR and peak V02 by 14% and 9%, respectively), albeit in a more severely impaired group of patients with COPD (training three times weekly for 12 weeks at an average exercise intensity equivalent to 50% of baseline WR).