Abstract
This study analyzed the breathing pattern of healthy subjects during eccentric (ECC) exercise. Eight active male volunteers (28 ± 6 years, 180 ± 5 cm and 71 ± 8 kg) performed two incremental maximal cycle ergometer exercise tests in concentric (CON) and ECC conditions. Metabolic adjustments (VO2), breathing responses (ventilation VE; tidal volume Vt; breathing frequency fR) and electromyographic (EMG) activities of the vastus lateralis and biceps brachialis were measured and compared during ECC and CON exercise at the same mechanical power or VO2. At equal mechanical power (262.5 ± 32.0 W) VO2 and VE were significantly lower in ECC than CON exercise (ECC/CON ratio 1/5; p≤0.01). At the same VO2 (1904 ± 63 ml• min-1 in CON and 1823 ± 231 ml• min-1 in ECC), VE was comparable during CON and ECC exercise, whereas the breathing responses, but not blood oxygenation, were significantly different (Vt: 2.07 ± 0.27 l CON vs. 1.35 ± 0.35 l ECC, p<0.01; fR: 26.4 ± 3.7 breath• min-1 CON vs. 36.1±10.4 breath• min-1 ECC, p<0.05). EMG activities were similar for the vastus lateralis, but higher for the biceps brachialis in ECC than CON conditions (32.4 ± 9.6 µV vs. 12.5 ± 5.2 µV, p<0.01). Changes in the ECC breathing pattern might be related to chest expansion limitations imposed by the subjects’ position on the cycle ergometer, as suggested by the higher biceps brachialis EMG activity. These changes may cause dynamic hyperinflation, which should be taken into account when designing rehabilitation programs.
- © 2013 ERS