Value of isokinetic strength testing for hamstring injury risk assessment: Should the 'strongest' mates stay ashore?

Although isokinetic strength testing is commonly used in hamstring strain injury (HSI) rehabilitation and prevention, research findings concerning its predictive value remain inconclusive. Existing research focuses on peak torque (PT) and angle of PT, not analysing the torque behaviour throughout the testing range of motion (ROM). This study intended to assess the value of isokinetic curve evaluation in association with HSI. A sample of 116 male football players with and without a recent HSI history was submitted to bilateral isokinetic assessment of the knee and hip muscles. Raw isokinetic data were filtered and normalized prior to curve analysis submission in MATLAB. Torque development of each muscle group throughout the entire testing ROM was assessed using HSI history as an independent variable. Curve analysis revealed significant differences in torque behaviour in function of injury history. Players with an HSI history demonstrated significantly stronger concentric knee flexion and extension, eccentric knee extension and concentric hip extension patterns compared to the controls and their uninjured limb. HSI history was also associated with lower concentric hip flexion torques and lower mixed H:Q ratios compared to the control group and their contralateral limb. HSI history was associated with altered knee and hip muscle strength profiles, potentially due to isolated focus on local strength training in rehabilitation or mechanisms of neuromuscular inhibition. Because the differences in torque amplitude were range-dependent and did not systematically concur with the point of PT achievement, isokinetic strength evaluation should most probably be conducted using curve analysis.