Effect of Fatigue Of Ankle Dorsiflexors On Muscle Synergies During Body Sway

Open Access
Basith, Mohammed A
Area of Honors:
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Mark Latash, Thesis Supervisor
  • Stephen Jacob Piazza, Honors Advisor
  • fatigue
  • synergies
The main purpose of this experiment was to test the effect of fatigue of the ankle dorsiflexors (primarily the tibialis anterior muscle group) on multi-muscle synergies during voluntary sway. The hypothesis posed was that fatigue would lead to changes in the M-mode compositions and that fatigue would lead to higher variance in the elemental variables (M-modes), but that this variance would not affect the performance variable (COP stabilization). Confirming this hypothesis would mean that multi-muscle synergies were used to organize muscles during voluntary sway under fatigue conditions. Subjects performed a series of 12 voluntary sway trials, first without fatigue trials. Subjects then performed a second set of 12 voluntary sway trials with a two minute fatigue trial between each two voluntary sway trial. Data concerning center-of-pressure stabilization and electromyography activation (for twelve muscle groups) was collected. Analysis of the data led to the conclusion that there was a clear difference between muscle activation, M-mode compositions, and variance in the M-modes pre-fatigue and post-fatigue. Increases in activation and variance were seen in many of the muscle groups studied. This variance did not significantly affect the performance variable, though with much of the post-fatigue variance being attributed to VUCM, or variance not affecting the performance variable. There was a significant amount of “bad” variance measured by VORT, though, which suggests that the synergy between the muscles may not have been 100% efficient in maintaining performance variable performance.