Critical power test for ramp exercise.

Accepted: 23 March 1995 Sirs: Hugh Morton has recently proposed a critical power test for ramp exercise on a cycle ergometer (Morton 1994). This new test was assumed to be more reliable than the usual critical power test the protocol of which consists in performing several periods of constant-load exercise up to exhaustion. Indeed, it was postulated that the reliability of exhaustion time of long lasting exercise was low in comparison with the reliability of the duration of a ramp test which was assumed to depend less on motivation. According to Morton's model, the duration (T) of ramp test depends on criti- cal power (CP), ramp slope (S) and anaerobic work capacity (AWC), only: T = CP/S + 2 AWC (1) However, the validity of this procedure is question- able. Although T depends on CP and AWC, maximal aerobic power (Pmax) is probably the main physiolo- gical factor determining ramp exercise duration. In fact, the model proposed by Morton implicitly assumed that CP was equal to Pm~x" Indeed, as shown in Fig. 1 of Morton's paper, all the energy was assumed to be supplied by the anaerobic metabolism beyond CP and consequently CP corresponded to