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

For each patient in the training group, peak physiologic measurements at the WR attained at the end of tolerable exercise in the baseline ergometer test were compared to measurements at an identical WR during the outcome test. Accordingly, significant mean reductions in VE (13%), VC02 (9%), V02 (8%), VE/V02 (4%), and HR (5%) were found (Table 3). Furthermore, the AT as detected by the V-slope technique significantly increased by 10% following training (Table 3; Fig 2). Changes in VC02 were significantly correlated with changes in VE at a given exercise WR (r = 0.63; p = 0.002). Significant changes in the above physiologic variables within the nontraining control group were not observed (Fig 2).
Clinically, there was a very modest, though statistically significant, increase in both FEV1 and FVC by 4% and 6%, respectively, following training (Table 2). No significant correlations were found between the degree of airflow limitation (as quantified by % predicted FEV1) with changes in any of the measured physiologic parameters at peak or identical levels of exercise (r < 0.4; p > 0.05 for all variables evaluated). Furthermore, following 12 weeks of training, the magnitude of improvement in peak WR and reductions in VC02, VE, and HR at an identical WR during the incremental test were comparable and independent of baseline pulmonary dysfunction (Table 4). add comment

Discussion
This study provides evidence that a 12-week pulmonary rehabilitation program with moderate exercise workloads performed twice weekly can lead to a physiologic training response irrespective of the degree of airflow limitation. Furthermore, in contrast to other studies, there was a significant but very modest clinical impact on ventilatory capacity.
The improvements in exercise tolerance were manifest not only by attainment of higher peak exercise responses (in WR, VE, and V02), but also by reduced ventilatory requirement at a given level of exercise. Furthermore, the magnitude of improvement in exercise tolerance was comparable over a spectrum of airflow limitation.
Table 3—Effects of Rehabilitative Exercise Training on Responses to Identical Levels of Exercise in the Incremental Exercise Test (n = 60)

Variables Before After % Changet
Vo2, L/min 1.14 ± 0.45 5 8
Vco2, L/min 1.13 ± 0.49   9
VE, L/min 42.4 ± 16.1   13
VE/Vo2 37.6 ± 8.1   4
AT, L/min 0.86 ± 0.23 01 1 10
HR, beats/min 135 ± 15 128 ± 16| 5

Table 4—Effects of Rehabilitative Exercise Training on Peak WR and Physiologic Responses to Identical Levels of Exercise in the Incremental Exercise Test, Stratified by Severity of Airflow Obstruction

Variables % Predicted FEV1 < 40%(n = 28) % Predicted FEV1 > 40% (n = 32)
Before After % Changef Before After % Changef
Peak WR, W 63 ± 4 76 ± 5j 20 89 ± 6 18
Ve, L/min 35.3 ± 2.0   16 48.5 ± 3.0 11
Vco2, L/min 0.89 ± 0.06 10 1.35 ± 0.09   9
HR, beats/min 129 ± 3 122 ± 2 5 141 ± 2 134 ± 3 5