[Study of the type of physical effort exerted by competition in Supercross].

The authors draw up a tentative account of the physiological load a pilot bears during a Supercross event. Examination of heart frequency and blood lactate concentration curves during a series of races shows that this sport is not only highly stressful, but demands by the same token a muscular effort which has to be taken into account. Muscular work is of the mixed type, both aerobic and anaerobic, the share of the latter being of moderate importance, as it depends mainly on the technical proficiency of the driver.