The Impact of Exercise-Induced Muscle Damage on Online Control of Upper Limb Goal Directed Actions


Whether it is regaining our balance after slipping on ice or intercepting a ball after it takes an unexpected bounce, adjusting our movements to sudden perturbations requires the coordination and control of various muscle groups. Our ability to perform these corrections relies on sensory information derived from receptors in our muscles and joints. Previous research suggested this sensory information could be impaired after exercise training due to exercise-induced muscle damage (EIMD). The objective of this study was to determine if EIMD could impair online control to different types of target perturbations. Right-handed, recreationally active (<3 hours of weekly structured weight training) females performed four experimental sessions: two equipment familiarizations (S1-S2), a muscle damage exercise protocol (S3), and a 24-hours post-exercise assessment (S4). In each session, participants’ biceps maximal voluntary contraction was assessed using the Humac-Norm isokinetic dynamometer. Participants also completed a reaching task using the KINARM exoskeleton in S2-S4 where they reached to a visual target position using bicep flexion. To assess online control in the reaching task, participants performed one set of trials wherein the target jumped to a new location (TJ trials), and another set where a force (FP trials) was applied to the elbow joint. These trials were intermixed with control trials where no target movement occurred. Initial results revealed that participants’ reaching patterns were more variable on TJ and FP trials compared to control trials. These findings suggest that EIMD reduces the ability of individuals to correct to both visual and force perturbations.