Biomechanical response of skeletal muscle to eccentric contractions

•Eccentric contractions (lengthening of activated muscle) are unique mechanically because the force generated by muscle when shortening is very distinct mechanically from the force generated when the muscle is lengthening.•After eccentric contraction, a predictable series of events occurs that ultimately leads to protection from further injury. The entire process can require 7–14 days for completion.•The earliest event that we have detected after eccentric contraction is disruption of the muscle cell's cytoskeleton, which may provide insights into the mechanisms of injury. The forced lengthening of an activated skeletal muscle has been termed an eccentric contraction (EC). This review highlights the mechanically unique nature of the EC and focuses on the specific disruption of proteins within the cell known as cytoskeletal proteins. The major intermediate filament cytoskeletal protein, desmin, has been the focus of work in this area because changes to desmin occur within minutes of ECs and because desmin has been shown to play both a mechanical and biologic role in a muscle's response to EC. It is hoped that these types of studies will assist in decreasing the incidence of muscle injury in athletes and facilitating the development of new therapies to treat muscle injuries.