Isokinetic dynamometry is widely considered the gold standard in mechanical muscle performance testing. Invariably, the moment-position raw data obtained from the dynamometer is directly analysed although kinematic inaccuracies may inherently exist. OBJECTIVE: To quantify the differences between two processing methods of isokinetic raw data: one based on the device`s own software and one using a hybrid kinematic procedure. METHODS: Seventy-six healthy male participants performed unilateral concentric knee extensor (Qcon) (90 ° ROM) and eccentric knee flexor (Hecc) tests (110 ° ROM) at 150 ° /s. The knee angles were recorded by two high-speed cameras per body side. RESULTS: Compared to isokinetic data, kinematic analysis revealed reduced knee ROM of 17 ° for Qcon and of 21 ° for Hecc. Thus, the mean `isokinetic` angular velocity declined to 121 and 122 ° /s, respectively. The angles of peak moment changed significantly (- 5 ° for Qcon, + 20 ° for Hecc). Contractional work decreased (- 20%) only for Qcon. The moments and angles derived from analysis of the DCR at the equilibrium point (DCRe) rose by 7% and 20% respectively when the isokinetic raw data were linked with kinematic data. The comparison of both processing methods revealed very high (R 2 = 91%) and high (R 2 = 69%) relationships for DCRe moments and angles. CONCLUSIONS: Isokinetic raw data comprise kinematic inaccuracies caused by axis misalignment, evasive movements and anatomical features. Although a hybrid kinematic procedure is more time-consuming, it may enable a more valid clinical interpretation of the test findings.
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