Age-specific neuromuscular interaction during elderly habitual running

Area of Science:

• Biomechanics
• Gerontology
• Exercise Physiology

Background:

• Advancing age is associated with increased tendon compliance and shorter fascicle lengths.
• Movement efficiency may be enhanced in older adults if muscle activation during dynamic movements matches that of younger adults.

Purpose of the Study:

• To investigate age-specific behaviors of the medial gastrocnemius (MG) fascicles and tendinous tissues.
• To examine lower-leg muscle activities in well-trained elderly runners compared to younger runners during treadmill running.

Main Methods:

• Recruited 11 elderly (ELD) and 11 young (YOUNG) well-trained runners.
• Measured MG fascicle length (Lfa) and tendinous tissue length (LTT) using ultrasonography during treadmill running at preferred speeds.
• Simultaneously recorded kinematics and lower-leg muscle activities.

Main Results:

• Elderly runners showed greater LTT during the entire contact phase compared to younger runners (P < 0.001).
• Higher co-activation of lower-leg muscles was observed in ELD compared to YOUNG (P < 0.01).
• ELD exhibited smaller changes in Lfa and greater LTT shortening during contact than YOUNG (P < 0.001).

Conclusions:

• Elderly runners demonstrate different muscle activation patterns compared to younger runners.
• These altered activation strategies in elderly runners may influence the utilization of tendon elasticity.
• Findings suggest that elderly individuals may not activate muscles identically to younger adults during running.