A. Lamont1, M. Welsh2, G.E. McCall1, FACSM

1University of Puget Sound, Tacoma, WA; 2Quest University Canada, Squamish, BC

Exercise-induced muscle damage (EIMD) results in reduced strength, inflammatory responses, delayed-onset muscle soreness (DOMS), and muscle/joint stiffness. Joint stiffness has traditionally been measured by changes in static joint positions or a perceived resistance to movement. PURPOSE: To develop a novel protocol to quantify the effects of EIMD of the elbow flexors on joint stiffness by measuring torque during passive isokinetic elbow movements throughout the full range of motion. METHODS: Subjects (n=7) performed 50 maximal eccentric elbow extensions with their nondominant arm to induce EIMD, with the dominant arm as a control. Several measurements, including mid-arm circumference, relaxed elbow angle, perceived soreness rated from 0-100 on a visual analog scale (VAS), elbow torque during passive movement (5 and 15° • sec-1), and isokinetic maximum strength (15° • sec-1) were performed on each arm before the EIMD protocol and 1,2,3, and 7 days during recovery. A 2-factor (arm x day) repeated measures ANOVA was used to compare the main effects and interaction of each dependent variable, with α<0.5 as significant. RESULTS: Significant arm x day interactions (p<0.05) existed for perceived soreness, isokinetic maximum strength, and relaxed elbow angle. Soreness in the nondominant arm increased by 31.5 on the VAS after the EIMD protocol. Peak soreness occurred on recovery day 1, and ratings returned to baseline by recovery day 7. Soreness in the dominant arm remained <6 on the VAS throughout the study. Maximal strength in the nondominant arm decreased by 8.75% following EIMD, with peak strength loss on recovery day 1. Strength in the dominant arm increased slightly over the course of the study. Relaxed elbow angle in the nondominant arm became more flexed by 3.43° following EIMD. Peak flexion occurred on recovery day 1, and values returned to baseline by recovery day 7. No main effects or interactions were observed for arm circumference or elbow joint torque during passive isokinetic movements. CONCLUSION: The changes in perceived soreness, isokinetic maximum strength, and relaxed elbow angle following eccentric exercise indicate that EIMD occurred in the nondominant arm. Despite the presence of EIMD in the nondominant arm, changes in passive elbow joint stiffness during isokinetic movement were not observed.

Supported by the Washington NASA Space Grant Consortium and the University of Puget Sound Enrichment Committee.

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