Effects of aging on mechanical efficiency and muscle activation during level and uphill walking

• Published in: Journal of electromyography and kinesiology 2015-02, Vol.25 (1), p.193-198
• Main Authors: Ortega, Justus D, Farley, Claire T
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aging; Aging - physiology; Co-activation; Efficiency; Female; Gait; Humans; Leg - growth & development; Leg - physiology; Male; Muscle Contraction; Muscle Development; Muscle, Skeletal - growth & development; Muscle, Skeletal - metabolism; Muscle, Skeletal - physiology; Oxygen Consumption; Physical Medicine and Rehabilitation; Walking; Walking - physiology
• ISSN: 1050-6411; 1873-5711; 1873-5711
• DOI: 10.1016/j.jelekin.2014.09.003

Abstract Purpose: The metabolic cost of walking is greater in old compared to young adults. This study examines the relation between metabolic cost, muscular efficiency, and leg muscle co-activation during level and uphill walking in young and older adults. Procedures: Metabolic cost and leg muscle activation were measured in young (22.3 ± 3.6 years) and older adults (74.5 ± 2.9 years) walking on a treadmill at six different slopes (0.0–7.5% grade) and a speed of 1.3 m s−1 . Across the range of slopes, ‘delta mechanical efficiency’ of the muscular system and antagonist muscle co-activation were quantified. Main findings: Across all slopes, older adults walked with a 13–17% greater metabolic cost, 12% lower efficiency, and 25% more leg muscle co-activation than young adults. Among older adults, co-activation was weakly correlated to metabolic cost ( r = .233) and not correlated to the lower delta efficiency. Conclusion: Lower muscular efficiency and increased leg muscle co-activation contribute to the greater metabolic cost of uphill slope walking among older adults but are unrelated to one another.