Title: “The effect of exercise-induced fatigue and eccentric muscle damage on kinaesthesia”
Thesis Supervisor: Dr. J Timothy Inglis (Kinesiology)
Committee members: Drs. Romeo Chua and Mark Carpenter (Kinesiology)
Chair: Dr. Jean-Sebastien Blouin (Kinesiology)
Abstract: The senses of position and movement are known collectively as kinaesthesia. Muscle spindles are length sensitive receptors, considered pivotal to these senses. Mechanical muscle vibration artificially stimulates muscle spindles and this can lead to illusory limb postures and movements, thereby disrupting kinaesthesia. Exercise induced fatigue also impairs kinaesthesia and this impairment persists if the exercise involves lengthening contractions that create eccentric muscle damage. It is not entirely clear why these lasting impairments occur. Using a targeted movement sequence with the unseen arm (a task that relies heavily on muscle spindles), this study utilized a novel paradigm to investigate task performance both before and after an eccentric based exercise protocol. By investigating the influence of vibration applied to the involved musculature, the results provide insight into how exercise acutely disrupts kinaesthesia. It was found that mechanical muscle vibration created a robust effect on task accuracy at all points during the study, causing participants to undershoot the targets (as previously described in the literature). The effects of exercise also caused a consistent error in task performance, but did not appear to influence the effect of vibration. This suggests that the nervous system continues to rely heavily on muscle spindles, even when they reside in a muscle exposed to damaging eccentric contractions.