Kinematic analysis of isokinetic knee flexor and extensor tests

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BACKGROUND: 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 reduced the knee’s ROM by 17° for Qcon and by 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% when the isokinetic raw data were linked with kinematic data. The comparison of both processing methods revealed very high (R²=91%) and high (R²=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
Original languageEnglish
JournalIsokinetics and Exercise Science
Volume26
Issue number1
Pages (from-to)1-8
Number of pages8
ISSN0959-3020
DOIs
Publication statusPublished - 2018

ID: 3102227

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