Loss of the dystrophin glycoprotein complex (DGC) or a subset of its components can lead to muscular dystrophy. However, the patterns of symptoms differ depending upon which proteins are affected. The absence of dystrophin leads to loss of the entire DGC and is associated with susceptibility to contractile injury. In contrast, muscles lacking gamma-sarcoglycan (-SG) display little mechanical fragility and still develop severe pathology. Animals lacking dystrophin or -SG were utilized in order to identify DGC components critical for sensing dynamic mechanical load. The extensor digitorum longus muscles from 7 week old normal (C57), dystrophin null (mdx), and -SG null (gsg-/-) mice were subjected to a series of eccentric contractions, after which ERK1/2 phosphorylation levels were determined. At rest, both dystrophic strains had significantly higher ERK1 phosphorylation, and gsg-/- muscle also had heightened ERK2 phosphorylation compared to wildtype controls. Eccentric contractions produced a significant and transient increase in ERK1/2 phosphorylation in normal muscle, whereas the mdx strain displayed no significant proportional change of ERK1/2 phosphoryation after eccentric contraction. Muscles from gsg-/- mice had no significant increase in ERK1 phosphorylation; however, ERK2 phosphorylation was more robust than C57 controls. The reduction in mechanically induced ERK1 phosphorylation in gsg-/- muscle was not dependent upon the age or severity of the phenotype, as muscle from both young and old (age 20 weeks) animals exhibited a reduced response. Immunoprecipitation experiments revealed that -SG was phosphorylated in normal muscle after eccentric contractions, indicating that members of the DGC are modified in response to mechanical perturbation. This study provides evidence that the SGs are involved in the transduction of mechanical information in skeletal muscle, potentially unique from the entire DGC.