General Exercise Training Improves Ventilatory and Peripheral Muscle Strength and Endurance in Chronic Airflow Limitation

We studied the impact of a 6-wk supervised, multimodality endurance exercise training program (EXT) on strength and endurance of ventilatory and peripheral muscles in patients with chronic air- flow limitation (CAL), and determined whether potential improvements contributed to relief of exer- tional breathlessness (B) and perceived leg effort/discomfort (LE), respectively. Twenty breathless patients with stable CAL (FEV 1 5 41 6 3% predicted; mean 6 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 inspiratory/expiratory pressures (MIP, MEP), inspiratory muscle endurance (V LIM ), quadriceps strength and endurance, exercise endurance, and submaximal cycle exercise with cardioventilatory and symptom responses. Measurements at baseline and pre-EXT were identical. Post-EXT, PFTs did not change; exercise endurance measured on the treadmill, cycle ergometer, arm ergometer, and by 6-min walk distance increased 40 6 8%, 43 6 10%, 12 6 5%, and 34 6 9%, respectively (p , 0.05); quadriceps strength increased 21 6 5% (p , 0.01); MIP and MEP increased 29 6 11% and 27 6 11%, respectively (p , 0.05); V LIM increased almost threefold (p , 0.05). At isotime near end-exercise, B, LE, carbon dioxide production ( CO2 ), oxygen consumption ( O2 ), ventilation, and breathing frequency (F) all fell after EXT (p , 0.05): D B correlated with D F (r 5 0.58, p , 0.01). Increased MIP and V LIM did not correlate with improved breathlessness or exercise endurance. Similarly, changes in quadriceps strength and endurance did not correlate with changes in LE or exercise endurance. In conclusion, general nonspecific EXT improved ventilatory and periph- eral muscle function in severe CAL, but such improvements did not appear to contribute significantly to reduced exertional symptoms and enhanced exercise performance. O'Donnell DE, McGuire M, Samis L, Webb KA. General exercise training improves ventilatory and peripheral muscle strength and endurance in chronic airflow limitation. AM J RESPIR CRIT CARE MED 1998;157:1489-1497. . V . V