Slower Walking Speed in Older Men Improves Triceps Surae Force Generation Ability

Area of Science:

• Biomechanics
• Gerontology
• Musculoskeletal physiology

Background:

• Older adults exhibit reduced walking speed compared to younger adults.
• Ankle plantarflexor muscles are hypothesized to play a key role in this age-related decline in locomotion.
• Understanding age-related changes in muscle-tendon function is crucial for addressing mobility limitations.

Purpose of the Study:

• To investigate age-related differences in triceps surae (calf muscles) muscle-tendon function during walking.
• To determine the contribution of plantarflexor function to the reduction in walking speed observed in older adults.

Main Methods:

• Ultrasound imaging measured medial gastrocnemius and soleus muscle fascicle lengths during walking in young and older men.
• Muscle-tendon unit and tendinous tissue lengths were calculated using joint kinematics.
• Ground reaction forces and electromyography of calf muscles were recorded.

Main Results:

• Older men exhibited a narrower muscle fascicle operating range and lower shortening velocity during peak force generation at their preferred speed.
• Plantarflexor fascicles contributed less to muscle-tendon unit length changes during stance in older adults.
• No significant differences in triceps surae function were found when comparing age groups at matched walking speeds.

Conclusions:

• Older adults' preferred slower walking speeds may be a strategy to enhance force generation and utilize tendinous tissue elasticity.
• These findings suggest that reduced plantarflexor strength contributes to slower walking speeds in older age.
• Optimizing muscle-tendon unit mechanics through adjusted gait parameters may be beneficial for older adults.