Increasing gastrocnemius activity during walking may elicit counterproductive effects on fascicle behaviour in older adults

Some evidence suggests that plantarflexor muscle fascicles in older adults operate at shorter lengths further down the ascending limb of the length-tension curve than in young adults. This may restrict how volitional increases in activation, for example in gait retraining, propagate to larger ankle moments during push-off. Here we found that increased plantarflexor activation while walking resulted in shorter fascicle lengths but no change in peak ankle moment. This outcome alludes to a structural bottleneck in ankle moment generation that may be functionally relevant in elderly gait.