title: Peak activation of lower limb musculature during high flexion kneeling and transitional movements.
abstract: Few studies have measured lower limb muscle activation during high knee flexion or investigated the effects of occupational safety footwear. Therefore, our understanding of injury and disease mechanisms, such as knee osteoarthritis, is limited for these high-risk postures. Peak activation was assessed in eight bilateral lower limb muscles for twelve male participants, while shod or barefoot. Transitions between standing and kneeling had peak quadriceps and tibialis anterior (TA) activations above 50% MVC. Static kneeling and simulated tasks performed when kneeling had peak TA activity above 15% MVC but below 10% MVC for remaining muscles. In three cases, peak muscle activity was significantly higher (mean 8.9% MVC) when shod. However, net compressive knee joint forces may not be significantly increased when shod. EMG should be used as a modelling input when estimating joint contact forces for these postures, considering the activation levels in the hamstrings and quadriceps muscles during transitions. Practitioner Summary: Kneeling transitional movements are used in activities of daily living and work but are linked to increased knee osteoarthritis risk. We found peak EMG activity of some lower limb muscles to be over 70% MVC during transitions and minimal influence of wearing safety footwear.
authors.affiliation: a Department of Kinesiology , University of Waterloo , Waterloo , Canada.
authors.forename: David C
authors.initials: DC
authors.lastname: Kingston
authors.affiliation: a Department of Kinesiology , University of Waterloo , Waterloo , Canada.
authors.forename: Liana M
authors.initials: LM
authors.lastname: Tennant
authors.affiliation: a Department of Kinesiology , University of Waterloo , Waterloo , Canada.
authors.forename: Helen C
authors.initials: HC
authors.lastname: Chong
authors.affiliation: a Department of Kinesiology , University of Waterloo , Waterloo , Canada.
authors.forename: Stacey M
authors.initials: SM
authors.lastname: Acker
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography / Q000379:methods; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology; D009784:Occupational Diseases / Q000517:prevention & control*; D020370:Osteoarthritis, Knee / Q000517:prevention & control*; D011481:Protective Clothing; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology; D012449:Safety; D012775:Shoes
keywords: EMG; footwear; knee; kneeling; occupational ergonomics