Mechanomyography; Lasers for non-invasive quantification of muscle recovery from exercise induced fatigue



Publication Details

Rosser, N. A., McAndrew, D. J. & Iverson, D. Mechanomyography; Lasers for non-invasive quantification of muscle recovery from exercise induced fatigue. Proceedings of the 2005 Australian Conference of Science and Medicine in Sport; Melbourne, Australia: 2005.


Muscle fatigue is a common clinical sign and possible precursor to musculoskeletal injury. Existing methods of detecting muscle fatigue qualify changes within muscle or across joints, but are expensive, invasive or difficult to use. A technique of mechanomyography utilising maximal percutaneous stimulation (known as the Muscle Displacement Laser {MDL}) is an easy non-invasive assessment tool, which may have considerable application in measuring muscle fatigue and determining recovery. Specifically, this study attempted to validate the MDL as a tool to measure muscle fatigue and determine the time-course of recovery from Delayed Onset of Muscle Soreness in human biceps brachii muscle. Methods: The protocol utilised concentric/assisted contractions performed in sets of 10 repetitions at 80% of subject’s 1RM. Volitional exhaustion during concentric contractions will occur, followed by 5 assisted repetitions till absolute fatigue occurs. RPE and MDL were assessed on consecutive days till recovery was achieved. Results: Preliminary evidence suggests that the muscle was fatigued following the protocol. Differences in MDL patterns were found between pre and post fatigue trials. Maximum displacement (Dmax) and contraction time (tc) decreased while relaxation time (tr) increased. Further results are pending analysis. Discussion: The MDL was found to be a valid means of detecting muscle fatigue and recovery from fatiguing exercise. Initial results indicate the muscle does not recover until the fifth day following the stimulus. This indicates that fatigued muscles are at an increased risk of injury during this period, which has implications for modifying training and recovery for people/athletes to reduce the deleterious risk of musculoskeletal injuries.

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