Analysis of the Reliability of a Method for Measuring Hamstring Active Peak Torque Angle

Introduction: Muscle length can be inferred from the length-tension relationship of the muscle. This relationship is traditionally investigated by measuring the peak torque produced by the muscle and the angle at which it is generated. Objective: The present study investigated the test-retest reliability of a method for measuring hamstring active peak torque angle in healthy young adults. Method: Twenty-five healthy individuals (22.88 ± 1.67 years) were assessed twice with an interval of three weeks. An isokinetic dynamometer was used in passive mode to assess hamstring passive torque. Muscle activity was monitored to ensure electromyographic silence. The dynamometer was also used in concentric mode to determine hamstring total torque. The active torque was obtained as the difference between total torque and passive torque. The active peak torque angle was used for the analysis. Results: There was no significant difference between the two measurements (t= 1.009; p= 0.323). The intraclass correlation coefficient for the active peak torque angle values obtained was 0.948 (p= 0.0001; 95% CI: 0.883 – 0.977). Conclusion: This study has shown that the method described is reliable for the quantification of active peak torque angle, thus suggesting that this method can be used to evaluate shifts in the torque-angle curve produced by muscle length changes.