Stretching skeletal muscle in vitro: does it replicate in vivo physiology?

Skeletal muscle is highly adaptable and responds to changes in loading through exercise or resistance training through a number of mechanisms resulting in increased muscle mass and changes in contractile phenotype. To further understand and study the molecular mechanisms underlying the adaptive response of muscle, a number of in vitro culture systems have been developed that utilise mechanical loading or stretching of the cultured muscle to recapitulate the adaptations observed in vivo. Here we review the use of such stretching regimes for engineered muscle constructs and assess how well these in vitro systems mimic in vivo muscle physiology and adaptation.