Force-velocity relationship on a cycle ergometer and knee-extensor strength indices.

Maximal anaerobic power (Pmax) is often measured on a friction loaded cycle ergometer by means of an all-out exercise against a single braking force or from the force-velocity relationship. The relationship between braking force (F) and peak velocity (V) in cycling is linear: V = V0(1-F/F0) where V0 and F0 correspond to the intercepts with the velocity axis and force axis, respectively. The aim of the present paper was to test the hypothesis that parameter F0 expresses strength ability. The first study (12 male volleyball players) showed significant correlations between F0 and maximal isometric voluntary force (MVF) or maximal isometric rate of force development (MRFD) during isometric knee extension with data expressed either in absolute units (0.66 < r < 0.81, P < 0.01) or related to quadriceps muscle mass kgQ or kgQ2/3 (0.58 < r < 0.82, 0.05 < P < 0.001). In the second study (24 male athletes), F0 was significantly correlated with the peak torques in isokinetic Biodex knee extension at four angular velocities (0, 1.57, 3.14 and 4.19 rad.s-1) with the values expressed in absolute units (0.49 < r < 0.83, 0.05 < P < 0.001). When the results were related to kgQ or kgQ2/3 the correlation coefficients increased with velocity (0.22 < r < 0.69) and were significant (0.05 < P < 0.001) except at 0 rad.s-1. Nevertheless, the interest of the determination of F0 in addition to Pmax is questionable because similar coefficients of correlation were obtained between Pmax and strength performances.