Respiratory muscle strength is decreased after maximal incremental exercise in trained runners and cyclists

The respiratory muscle fatigue seems to be able to limit exercise performance and may influence the determination of maximal oxygen uptake (V̇O_2max) or maximum aerobic work rate during maximal incremental test. The aim of this study was therefore to investigate whether maximal incremental exercise decreases respiratory muscle strength. We hypothesized that respiratory muscle strength (maximal pressure) will decrease after maximal incremental exercise to exhaustion. 36 runners and 23 cyclists completed a maximal incremental test on a treadmill or a cycle ergometer with continuous monitoring of expired gases. Maximal inspiratory (MIP) and expiratory (MEP) pressure measurements were taken at rest and post- exercise. At rest, the MIP and MEP were 140±25 and 172±27 in runners vs. 115±26 and 146±33 in cyclists (p<0.05 between groups, respectively). The rest values of MIP and MEP were correlated to the V̇O_2peak in all athletes, r=0.34, p<0.01 and r=0.36, p<0.01, respectively. At exhaustion, the MIP and MEP decreased significantly post- test by 13±7% and 13±5% in runners vs. 17±11% and 15±10% in cyclists (p>0.05), respectively. Our results suggest that respiratory muscle strength is decreased following maximal incremental exercise in trained runners and cyclists.