Thesis (M.Sc.) - Cairo University - Faculty of Physical Therapy - Department of Biomechanics

Background : Localized muscle fatigue is a factor that appears to impair postural control. A number of studies reported an increase in postural sway with localized muscle fatigue. Yet, there is lack of knowledge that supports the effect of different muscle group fatigue on postural control. Purpose: The purpose of the study was to determine the effect of muscle fatigue on postural control and whether the effects of localized muscle fatigue on postural control differ among three muscle groups (ankle plantar flexors, knee extensors, and back extensors). Methods: Thirty-three males participated in the study with mean ± SD age of 20.9 ± 1.6 years, height 176 ± 7.5 cm, body mass 75.8 ± 9 kg, and body mass index 24.4 ± 2.3 kg/m2. Biodex Isokinetic Dynamometer was used to induce fatigue of three muscle groups(ankle plantar flexors, knee extensors, and back extensors).The muscle to be fatigued was randomly chosen by each participant by picking up a paper from 3 folded papers. Participants performed a concentric-eccentric contraction of the examined muscle group at 30{u00B0}/sec angular velocity. Biodex Balance System was used to assess postural control (overall stability index, antero-posterior stability index, and medio-lateral stability index) during double limb stance and single limb stance (alternatively for the right and left limb) before and after the induction of fatigue. The fatigue was induced on the participant{u2019}s dominant limb for ankle and knee muscles. Findings: Repeated measures MANOVA revealed that there were a significant increase (p<0.05) in the overall, AP and ML stability indices in the post-fatigue compared to the pre-fatigue condition at bilateral standing and unilateral standing for the three muscle groups. Additionally, there were higher significant increase (p<0.05) in all dependent variables at the back extensors compared to ankle planter flexors and knee extensors. As well as, there were higher significant increase (p<0.05) in all dependent variables at the ankle planter flexors compared to knee extensors

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