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Abstract

Understanding how gripping handles influence force production of knee extensors and flexors during different types of muscle contractions is crucial to obtain consistent isokinetic strength testing results. While it has been investigated the effect of gripping handles in the isometric and concentric contractions of the knee joint at various velocities, there is a lack of evidence of how gripping handles affectknee extensors and flexors in eccentric contraction. PURPOSE: This research was conducted to investigate the effect of gripping handles on the force production of the knee extensors and flexors during concentric, eccentric, and isometric contractions at various velocities. METHODS: Thirty healthy individuals (11 Males: Age = 21.727 ± 1.272 yrs, Height = 1.790 ± 0.088 m, Body Mass = 86.686 ± 18.179 kg; 19 females: Age = 21.895 ± 1.524 yrs, Height = 1.668 ± 0.068 m, Body Mass = 67.388 ± 12.397 kg), tested Isokinetic strength at various velocities with and without gripping handles. A series of tests were performed at -90, -60, -30, 0, 60, 120, and 180 °/s on individuals’ preferred limb. The knee joint torque was normalized by each participant’s body mass and shin length (N/kg). One-way repeated measures MANOVAs for each knee extensor and flexor were performed. T-tests were then performed to determine different velocities significances between grip conditions. RESULTS: The gripping handles significantly increased force production of knee extensors (F = 3.170, p < .05), but the force production of knee flexors were not affected by the grip conditions (F = 0.770, p = 0.619). The post-hoc analyses indicated that the gripping handles increased force production in isometric (t = -2.809, p < .05), and all velocities of the concentric contraction (60°/s: t = -2.949, p < .05; 120°/s: t = -3.967, pCONCLUSION: This study found that gripping handles could affect the force production of the knee extensors in the isokinetic strength test. The results suggest that the use of handles on the isokinetic dynamometer should be considered to measure the pure strength of the knee extensors with minimized compounding factors.

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