Cardiopulmonary loading in motocross riding.

The present study was designed to examine physiological responses during motocross riding. Nine Finnish A-level motocross riders performed a 15-min ride at a motocross track and a test of maximal oxygen uptake ([Vdot]O2max) in the laboratory. Cardiopulmonary strain was measured continuously during the ride as well as in the [Vdot]O2max test. During the ride, mean [Vdot]O2 was 32 ml · kg-1 · min-1 (s = 4), which was 71% (s = 12) of maximum, while ventilation (VE) was 73% (s = 15) of its maximum. The relative [Vdot]O2 and VE values during the riding correlated with successful riding performance (r = 0.80, P < 0.01 and r = 0.79, P < 0.01, respectively). Mean heart rate was maintained at 95% (s = 7) of its maximum. Mean blood lactate concentration was 5.0 mmol · l-1 (s = 2.0) after the ride. A reduction of 16% (P < 0.001) in maximal isometric handgrip force was observed. In conclusion, motocross causes riders great physical stress. Both aerobic and anaerobic metabolism is required for the isometric and dynamic muscle actions experienced during a ride. [ABSTRACT FROM AUTHOR]