Muscle strength imbalance in the hip joint caused by fast movements

Eleven male sportsmen at the age of 24.3+/-4.5 were examined. Their hip joint flexors and extensors were tested by an REV-9000 Technogym dynamometer system during isokinetic movements at angular velocities of 100 (low) and 200 (high) degrees/s. The range of hip joint movements was from 30 (inflexion) to 130degrees (in extension). Torque values and their ratios for hip flexors and extensors at different angular positions were obtained and compared. It is shown that, at high speeds, the flexion movement significantly raises (p < 0.001) the torque ratios of flexors and extensors inflexion positions of the hip (50 and 60degrees). These ratios approximately twofold exceed their values at moderate velocities. The weakness of hip joint extensors in extreme flexion positions of the hip may cause injury of this group of muscles at fast movements.