The validity of isokinetic knee extensor endurance measurements with reference to treadmill running capacities

The validity of isokinetic knee extensor endurance measurements with reference to treadmill running capacities was investigated. Nine male elite middle-distance runners completed a test consisting of 100 repetitive maximal eccentric and 100 concentric knee extensor actions where peak torque (Nm) and work (J) were measured. On a different day, submaximal and maximal treadmill tests were performed. Stepwise regression analysis was applied to determine the isokinetic variables with the greatest influence on the selected treadmill running capacities, including submaximal oxygen uptake (VO(2)) and maximal blood lactate. Eccentric total work was significantly and negatively related to submaximal VO(2) at all three running velocities investigated (12, 14, and 15 km.h(-1)). The R(2) values ranged from 0.48-0.59 for V0(2) ml.kg(-0.75).min(-1), indicating that 48-59 % of the variability in VO(2) ml.kg(-0.75).min(-1) could be accounted for by eccentric total work. The corresponding R(2) values for VO in ml.kg(-1).min(-1) were 0.50-0.58. Concentric relative endurance was significantly and negatively related to maximal blood lactate (R(2) = 0.73). This study has shown that isokinetic knee extensor endurance measurements of eccentric total work and concentric relative endurance are substantially related to measures of treadmill running capacity, as expressed by submaximal V02 and maximal blood lactate. It is suggested that these isokinetic measures may be used to evaluate specified running capacities in male elite middle-distance runners.