Articulate torque and electromyographic activity of biceps femoris and semitendinosus muscles during isokinetic knee flexion movements in soccer athletes

Abstract

The objective of the present study was to analyze the articulate torque (TO) and the electromyographic activity (EMG) of soccer athlete’s long head Biceps Femoris (BF) and Semitendinosus (ST) muscles during isokinetic knee fl exion movements (concentric-CON and eccentric-ECC actions) at differing velocities, carried out in the ventral decubitus position. Fourteen soccer players aged 19 and 20 years old (71.2 ± 6.5 kg, 176.6 ± 6.4 cm) were enrolled from the Associação Atlética Ponte Preta under- 20 team. They followed a protocol specifying 5 repetitions of fl exion (CON and ECC action) of the knee at three velocities (60, 180 and 300º/s) at random. The recovery interval between series adopted was 3 minutes. EMG Activity was recorded using surface electrodes and data were expressed in terms of root mean squares (RMS). Statistical analysis employed analysis of variance (Friedman test) for repeated measures followed by the Wilcoxon test when necessary, with the level of signifi cance set at P<0.05. The highest TO fi gures were observed at 60º/s velocity in the CON phase. There was no signifi cant variation in TO between different velocities in the ECC contraction. Moreover, the ECC phase had higher TO values, irrespective of velocity or repetitions. Some of the repetitions of the CON phase at 60º/s exhibited signifi cant difference between the BF and ST muscles. However, in general, the RMS values were not signifi cantly modifi ed by variations in velocity or type of contraction in the BF and ST muscles. Finally, the RMS/TO ratio was not linear under the experimental conditions studied, since, although TO values were different at different velocities and between CON and ECC contraction, whereas the RMS values remained steady.