Understanding muscle architectural adaptation: macro- and micro-level research.

Recent research using muscle-imaging techniques has revealed a remarkable plasticity of human muscle architecture where significant changes in fascicle lengths and angles have resulted from the chronic performance, or cessation, of strong muscle contractions. However, there is a paucity of data describing architectural adaptations to chronic stretching, disuse and immobilization, illness, and aging, and those data that are available are equivocal. Understanding their impact is important in order that effective interventions for illness/injury management and rehabilitation, and programs to improve the physical capacity of workers, the aged and athletes can be determined. Nonetheless, recent advances in myocellular research could provide a framework allowing the prediction of architectural changes in these understudied areas. Examination of the site-specific response to mechanical stress of calpain-dependent ubiquitin-proteasome proteolysis, or of the cellular response to stress after the knockout (or incapacitation) of sarcomeric and cytoskeletal proteins involved in cellular signal transduction, provides an exciting paradigm by which myocellular adaptation can be described. Such research might contribute to the understanding of macro-level changes in muscle architecture. Copyright (c) 2005 S. Karger AG, Basel.