(Neuromuscular and cardio-respiratory changes induced by long cycling exercise)

The effects of prolonged cycling on cardiovascular and neuromuscular parameters were studied in 9 endurance-trained subjects during a 5 h exercise sustained at 55% of the maximal aerobic power. Oxygen uptake, minute ventilation, and heart rate significantly increased (P <0.01) throughout the 5 h cycling exercise, by 15.5 (4.9%, 17.9 ( 6.6%, and 11.3 ( 5.4%, respectively whereas pedalling rate significantly (P < 0,05) decreased by 10 rates per minute (rpm). Maximal voluntary concentric contractions (120°.s-1 and 240°.s-1) of the knee extensors muscles decreased respectively by 8.5 + 0.8% (P <0.01) and 9.3 + 1 % (P < 0.05) following the 5 h exercise. This decrease in strength was associated with a significant reduction in electromyographic activity of the vastus lateralis (P <0,01) and vastus medialis (P