Evolution des taux plasmatiques des LDH (lacticodeshydrogénase), CPK (créatine phosphokinase) et de la myoglobine à l'issue d'une course de 100 km et d'un triathlon

The elevation of plasma levels of lactate dehydrogense (LDH), creatine phosphokinase (CPK) and myoglobin under the effect of prolonged physical exercise is considered as a biochemical index of muscle cell destruction. These biochemical parameters were used to evaluate the comparative effects of a 100 km race and a triathlon of the same duration upon muscle function. Venous blood samples were drawn from 8 long distance runners (the 100 km race at Belvès) and 8 participants in the Nice triathlon (swim 3 km, cycle 120 km, run 32 km) before the events, at the end and 4 days after. Leg muscle function was evaluated, using an isokinetic dynamometer CYBEX II before both events and 4 days later.The results show significant increases in these three parameters at the end of the competitive events. The plasma levels observed were higher at the end of the 100 km run (CPK: 700 ± 200 VS 180 ± 90; LDH: 411 ± 30 VS 200 ± 5; myoglobin 1100 ± 100 VS 730 + 400). The measurements made 4 days after these sporting events with the CYBEX revealed no change in the maximal effort of leg extensors and flexors. However, a slight reduction in the duration of exertion at this maximal level was noted. Foru days after these events, the CPK levels remained above the resting level for both groups studied, whereas the myoglobin values returned to basal levels in the triathletes, and the LDH values were the same as those observed at rest for both populations. These findings suggest that for a physical exertion lasting between 9 h 8 min and 8 h 20 min, the 100 km race causes more muscular lesions than the triathlon. The reduced time of exertion at maximal effort during the recovery period noted for both groups is an index representing a perturbation of the muscle function capacity, in spite of the normalization of the two biochemical parameters, LDH and myoglobin. The persistence of the slightly elevated CPK values suggests that this parameter is a better index of muscular lesions during the recovery phase.