Megan A Bryanton1,2, Martin Bilodeau3,4. 1. School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada. mbrya038@uottawa.ca. 2. Aging and Movement Laboratory, Bruyère Research Institute (BRI), 43 Bruyère St., Ottawa, ON, K1N 5C8, Canada. mbrya038@uottawa.ca. 3. School of Rehabilitation Sciences, University of Ottawa, Ottawa, ON, Canada. 4. Aging and Movement Laboratory, Bruyère Research Institute (BRI), 43 Bruyère St., Ottawa, ON, K1N 5C8, Canada.
Abstract
PURPOSE: The purpose of this investigation was to evaluate alterations in muscular effort and temporal characteristics of their activity during the sit-to-stand (STS) due to isolated fatiguing of the knee extensors, as indicated by declines in torque output. METHODS: Surface electromyography of the lower extremity was recorded in healthy young (n = 11) and older (n = 11) adults as they ascended from a seated position, before and after dynamic knee extension exercise. RESULTS: Knee extensor fatigue caused significant increases in soleus, gastrocnemius, and gluteus maximus relative effort (%MVC) in both age groups during the STS task. Rectus femoris %MVCs in both young and older adults significantly increased to similar extents throughout the STS movement, whereas vastus lateralis amplitudes only increased in preparation for seat-off. Muscle temporal characteristics appeared to generally be invariant with fatigue, except for earlier activation onset for the ankle musculature in older adult participants. CONCLUSIONS: These findings demonstrate that isolated knee extension fatiguing exercise caused compensatory changes in muscle activation patterns and increased reliance of non-fatigued muscles at the ankle and hip as well as increased activity of synergist muscles during the STS. Moreover, this occurred to similar extents in older adults who had lower knee extensor strengths and greater quadriceps %MVCs in comparison to their younger counterparts, regardless of fatigue condition.
PURPOSE: The purpose of this investigation was to evaluate alterations in muscular effort and temporal characteristics of their activity during the sit-to-stand (STS) due to isolated fatiguing of the knee extensors, as indicated by declines in torque output. METHODS: Surface electromyography of the lower extremity was recorded in healthy young (n = 11) and older (n = 11) adults as they ascended from a seated position, before and after dynamic knee extension exercise. RESULTS:Knee extensor fatigue caused significant increases in soleus, gastrocnemius, and gluteus maximus relative effort (%MVC) in both age groups during the STS task. Rectus femoris %MVCs in both young and older adults significantly increased to similar extents throughout the STS movement, whereas vastus lateralis amplitudes only increased in preparation for seat-off. Muscle temporal characteristics appeared to generally be invariant with fatigue, except for earlier activation onset for the ankle musculature in older adult participants. CONCLUSIONS: These findings demonstrate that isolated knee extension fatiguing exercise caused compensatory changes in muscle activation patterns and increased reliance of non-fatigued muscles at the ankle and hip as well as increased activity of synergist muscles during the STS. Moreover, this occurred to similar extents in older adults who had lower knee extensor strengths and greater quadriceps %MVCs in comparison to their younger counterparts, regardless of fatigue condition.
Authors: Paulo Cezar Rocha Dos Santos; Claudine J C Lamoth; Lilian Teresa Bucken Gobbi; Inge Zijdewind; Fabio Augusto Barbieri; Tibor Hortobágyi Journal: Front Aging Neurosci Date: 2021-06-21 Impact factor: 5.750
Authors: Paulo Cezar Rocha Dos Santos; Fabio Augusto Barbieri; Inge Zijdewind; Lilian Teresa Bucken Gobbi; Claudine Lamoth; Tibor Hortobágyi Journal: PLoS One Date: 2019-12-30 Impact factor: 3.240