A cross-sectional study comparing passive and eccentric modes of an isokinetic dynamometer to assess eccentric torque in trained athletes: Methodological considerations

Abstract

Some technical limitations to using the eccentric mode to measure peak eccentric strength of the hamstrings (PTH_ecc) were raised. PTH_ecc also has limited validity to predict performance or injury risk factor. Therefore, our aim was to compare PTH_ecc and other isokinetic variables tested in the eccentric and passive modes. Twenty male hockey players (20.2 ± 1.1 years; 179.7 ± 6.9 cm; 73.4 ± 7.1 kg and 12.2 ± 3.4% of body fat) performed maximal eccentric contractions of the hamstrings at 60°·s⁻¹ (three repetitions) and 180°·s⁻¹ (five repetitions) on both legs and using the eccentric mode and the passive mode (automatic movement of the lever arm) of the Biodex System 4 isokinetic dynamometer. The following variables were measured: PTH_ecc, the angle of peak torque (APT,°), angle-specific H_ecc torque at intervals of 10° and the rate of torque development (RTD) in the first 50 ms and the first 100 ms. The main results showed that compared to the eccentric mode, the passive mode led to a significantly greater PTH_ecc in the non-dominant leg only and significantly smaller APT, RTD and angle-specific H_ecc at angles close to knee flexion. In contrast, significantly greater angle-specific H_ecc was observed in the passive mode at angles close to extension (10°–40°). This suggests that, although eccentric or concentric modes can be used to compare isokinetic data to existing literature, it is preferable to use the passive mode to assess peak torque or torque close to knee extension. The eccentric mode might be better to assess variables at the start of movement such as RTD.