Aging limits the reduction of reactive muscle activity to perturbations but spares the retrieval of context-specific patterns with practice

Practice over three days reduces reactive muscle recruitment less in older adults than in younger adults during split-belt walking, especially in distal muscles.

• Why it matters: Re-adaptation slows with age, but the muscular mechanisms behind how reactive versus learned context-specific responses change with practice are unclear.
• What they did: Younger and older adults practiced split-belt walking for three days while surface electromyography from 10 muscles per leg was decomposed via linear regression into reactive (naive/early template) and context-specific (practiced template) components.
• The result: Older adults show smaller practice-related decreases in reactive recruitment, with no strong evidence that age alters context-specific recruitment, implying rehabilitation may target reactive mechanisms.

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