Fatigue affects peak joint torque angle in hamstrings but not in quadriceps

Abstract

Primary aim of this study was to investigate peak joint torque angle (i.e. the angle of peak torque) changes recorded during an isokinetic test before and after a fatiguing soccer match simulation. Secondarily we want to investigate functional H_ecc:Q_conc and conventional H_conc:Q_conc ratio changes due to fatigue.

Before and after a standardised soccer match simulation, twenty-two healthy male amateur soccer players performed maximal isokinetic strength tests both for hamstrings and for quadriceps muscles at 1.05 rad · s^‒1, 3.14 rad · s^‒1 and 5.24 rad · s^‒1. Peak joint torque angle, peak torque and both functional H_ecc:Q_conc and conventional H_conc:Q_conc ratios were examined. Both dominant and non-dominant limbs were tested.

Peak joint torque angle significantly increased only in knee flexors. Both eccentric and concentric contractions resulted in such increment, which occurred in both limbs. No changes were found in quadriceps peak joint torque angle. Participants experienced a significant decrease in torque both in hamstrings and in quadriceps. Functional H_ecc:Q_conc ratio was lower only in dominant limb at higher velocities, while H_conc:Q_conc did not change.

This study showed after specific fatiguing task changes in hamstrings only torque/angle relationship. Hamstrings injury risk could depend on altered torque when knee is close to extension, coupled with a greater peak torque decrement compared to quadriceps. These results suggest the use eccentric based training to prevent hamstrings shift towards shorter length.

Keywords:

• isokinetic
• injury prevention
• hamstrings to quadriceps ratio
• knee flexors