Abstract
Mechanical muscle tendon vibration activates multiple sensory receptors in the muscle and tendon. In particular, tendon vibration tends to activate the Ia afferents the strongest, but also will activate group II and Ib afferents. Tendon vibration can cause three main effects in the central nervous system: proprioceptive illusions, tonic vibration reflexes, and suppression of the stretch response. Noisy tendon vibration has been used to assess the frequency characteristics of proprioceptive reflexes and, interestingly there appeared to be no evidence for proprioceptive illusions or tonic vibration reflexes during standing [1]. However, it remains unknown if noisy vibration induces a suppression of the stretch response. Therefore, the purpose of this study was to investigate the effects of noisy and periodic tendon vibration on the flexor carpi radialis (FCR) muscle response to rapid wrist extension perturbations. We examined FCR stretch responses with and without periodic (20 and 100 Hz) and noisy (~10-100 Hz) tendon vibration. Additionally, participants performed this under the instruction set to either not respond to the perturbation or to respond as fast as possible. The key finding from this study was that both periodic and noisy vibration resulted in similar amounts of suppression of the stretch response. Additionally, it was found that a participant's intent to respond did not modulate the amount of suppression observed. The findings from this study provide a more detailed understanding of the effects of tendon vibration on the muscle stretch response. [1] Mildren et al., (2017), Journal of Applied Physiology, 122(5), 1134-1144Acknowledgments: NSERC