Figure 1.

Skeletal muscle atrophy younger and older adults in response to a period of unloading and a subsequent period of exercise rehabilitation. The black dotted lines indicate phenotypical differences in absolute levels of muscle mass. The yellow dotted line indicates a level in which low levels of leg lean mass results in disability and reduced functional ability (i.e., disability threshold). The red line indicates traditional trajectory in loss of muscle mass observed by disuse. The green dotted line indicates the potential of a nutritional strategy to offset muscle loss during disuse and improve rates of recovery following reambulation and rehabilitation. Importantly, the red dotted line indicates a proportion of older adults may not return to pre-disuse levels of muscle mass, particularly in the absence of aggressive retraining (Adapted from Perkin et al. 2016 [17]).