Affiliations: [a] Room 211, Memorial Gymnasium, Sports Medicine / Athletic Training Research Laboratory, University of Virginia, Charlottesville, VA 22903, USA
Note: [*] Corresponding author.
Abstract: Various devices and test protocols have been used during isokinetic assessment of human muscle performance. The purpose of this investigation was to examine the effects of continuous and interrupted test protocols and test device on concentric quadriceps peak torque (PT) production. PT was measured via two commonly employed isokinetic test devices (Cybex II and Kin-Com) and test protocols (interrupted (I) and continuous (C)). Thirty-one male subjects (× age 23.0 ± 2.07 years, × wt 78.2 ± 12.2 kg, × ht 177.8 ± 6.45 cm) were tested at 1.08 rad/s (600/second), 48 h apart on each device in random order. Because the devices correct for gravity differently, gravity correction was eliminated from all test conditions. Preload and damp were applied in order to replicate clinical protocols as closely as possible. Intraclass correlation coefficients (2,3) (and standard errors of measurement) were 0.88(7.52 N·m) (I) and 0.91 (7.04 N·m) (C) for the Kin-Com, and 0.98 (3.30 N·m) (I) and 0.92 (8.42 N·m) (C) for the Cybex. A 2 × 2 within subjects ANOVA demonstrated significant differences between Cybex (damped) and Kin-Com (preload) PT measures (P ≤ 0.05). An interaction for device × protocol demonstrated greater peak torque values for the I protocol (Kin-Com: 199.1 ± 44.9 N·m, Cybex: 181.7 ± 35.0 N·m) than for the C protocol (Kin-Com: 182.2 ± 35.5 N·m, Cybex: 183.3 ± 33.9 N·m) (P < 0.05) for the Kin-Com although the Cybex values were the same. Although both the interrupted and continuous protocols demonstrate high reliability, the interrupted protocol results in higher quadriceps PT values for the Kin-Com. We conclude that selection of test protocol influences assessment of quadriceps PT when using the Kin-Com isokinetic dynamometer.
