European Respiratory Journal vol:40 issue:2 pages:338-344
The improvement in exercise performance in response to exercise training varies highly from one patient with chronic obstructive pulmonary disease to another. It is possible that in a portion of patients the muscle stimulus applied during exercise training is insufficient to elicit training effects. We investigated whether patients presenting quadriceps contractile fatigue after training have more favorable effects of a rehabilitation program.Forty-six patients followed a three-month high-intensity exercise training program. Exercise capacity, quadriceps force and quality of life were measured before and after the program. Exercise training-induced quadriceps contractile fatigue was assessed after one month of rehabilitation with magnetic stimulation. A ≥15% fall in quadriceps force 15 minutes after training was considered as significant fatigue.Twenty-nine out of 46 patients (63%) developed significant fatigue. Patients with fatigue had a higher increase in six-minute walking distance (+57[+47,+103] vs. +17[-7,+46] m, p=0.0023) and Chronic Respiratory Disease Questionnaire score (+22±12 vs. +14±12 points, p=0.028) after the training program compared with patients without fatigue. Improvements in quadriceps force and maximal exercise capacity were similar in both subgroups.Patients who develop quadriceps contractile fatigue during exercise training show greater training effects in terms of functional exercise capacity and health-related quality of life.