Validity of the Nordic Angle application for assessment of relative eccentric knee flexion peak torque

This study aimed to investigate the relationship between the break-point angle (BPA) measured with the Nordic Angle app and absolute and relative eccentric knee flexion peak torques. Twenty-one male participants performed Nordic hamstring exercise (NHE) trials to determine their BPA, followed by absolute eccentric knee flexion strength testing. Absolute eccentric knee flexion peak torque was divided by body weight to calculate relative eccentric knee flexion peak torque. No Pearson correlation was observed between BPA and absolute eccentric knee flexion peak torque (r_p = −0.05, p = 0.85). Conversely, the Pearson correlation between BPA and relative eccentric knee flexion peak torque was significant (r_p = −0.54, p < 0.05). BPA measured with the Nordic Angle application was associated with relative eccentric knee flexor peak torque. As this study did not include a clinical population nor investigate hamstring injury incidence, clinical implications should be interpreted cautiously, and future research is required to determine whether BPA can predict hamstring injury risk.