GENERAL EXERCISE TRAINING IMPROVES VENTILATORY AND PERIPHERAL MUSCLE STRENGTH AND ENDURANCE IN CHRONIC AIR-FLOW LIMITATION

We studied the impact of a 6-wk supervised, multimodality endurance ex ercise training program (EXT) on strength and endurance of ventilatory and peripheral muscles in patients with chronic airflow limitation (C AL), and determined whether potential improvements contributed to reli ef of exertional breathlessness (B) and perceived leg effort/discomfor t (LE), respectively. Twenty breathless patients with stable CAL (FEV1 = 41 +/- 3% predicted; mean +/- SEM) were tested at 6-wk intervals at baseline, after a nonintervention control period (pre-EXT), and post- EXT. Measurements included: pulmonary function tests (PFTs), maximal i nspiratory/expiratory pressures (MIP, MEP), inspiratory muscle enduran ce (V-LIM), quadriceps strength and endurance, exercise endurance, and submaximal cycle exercise with cardioventilatory and symptom response s. Measurements at baseline and pre-EXT were identical. Post-EXT, PFTs did not change; exercise endurance measured on the treadmill, cycle e rgometer, arm ergometer, and by 6-min walk distance increased 40 +/- 8 %, 43 +/- 10%, 12 +/- 5%, and 34 +/- 9%, respectively (p < 0.05); quad riceps strength increased 21 +/- 5% (p < 0.01); MIP and MEP increased 29 +/- 11% and 27 +/- 11%, respectively (p < 0.05); V-LIM increased al most threefold (p < 0.05). At isotime near end-exercise, B, LE, carbon dioxide production ((V) over dot(CO2)), oxygen consumption ((V) over dot(O2)), ventilation, and breathing frequency (F) all fell after EXT (p < 0.05): Delta B correlated with Delta F (r = 0.58, p < 0.01). incr eased MIP and V-LIM did not correlate with improved breathlessness or exercise endurance. Similarly, changes in quadriceps strength and endu rance did not correlate with changes in LE or exercise endurance. In c onclusion, general nonspecific EXT improved ventilatory and peripheral muscle function in severe CAL, but such improvements did not appear t o contribute significantly to reduced exertional symptoms and enhanced exercise performance.