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Updated: May 10, 2026
14:02
Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Associations between muscle structure and contractile performance in seniors
Avleen Randhawa1, James M Wakeling
1Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada. ara46@sfu.ca
Clinical Biomechanics (Bristol, Avon)
|June 22, 2013
Summary
Aging sarcopenia reduces muscle belly thickness and pennation in seniors, leading to decreased belly gearing and power output during contractions. This study investigated these age-related muscle changes in the gastrocnemii.
Area of Science:
- Gerontology
- Muscle Physiology
- Biomechanics
Background:
- Sarcopenia, an age-related decline in muscle mass and function, alters muscle structure and mechanics.
- These alterations can significantly impact mobility and physical performance in older adults.
- Understanding these changes is crucial for developing interventions to maintain senior mobility.
Purpose of the Study:
- To investigate the effects of sarcopenia on muscle fascicle length, pennation, and belly thickness.
- To examine how sarcopenia influences belly gearing during isokinetic contractions.
- To compare muscle structure and mechanics between young adults and seniors.
Main Methods:
- Ultrasound imaging of the gastrocnemii muscles in young adults (20-40 years) and seniors (70-85 years).
- Muscle structure was assessed during standing and maximal plantarflexion at four constant velocities.
- Torque, position, and time were recorded during isokinetic contractions using a dynamometer.
Main Results:
- Seniors exhibited significantly lower muscle belly thickness and pennation compared to young adults in the standing position.
- During plantarflexion, seniors showed significantly reduced belly thickness, pennation changes, belly gearing, ankle torque, and power output.
- These reductions were observed in both the medial gastrocnemius (MG) and lateral gastrocnemius (LG) muscles.
Conclusions:
- Younger adults display higher pennation, associated with increased fascicle rotations and enhanced belly gearing.
- Seniors experience reduced fascicle rotations, leading to diminished belly gearing.
- The observed reduction in belly gearing in seniors did not fully account for the significant loss in muscle strength and power.
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