Efficiency of muscular contractions in mouse is different from that in frog

Traditionally, muscle efficiency studies were performed on frog muscles. Muscles of other animal species are assumed to have efficiency values similar to that in frog muscles. This assumption has not been vigorously tested. Our goal was to test this assumption by determining efficiencies of mouse and frog muscles and comparing them. Mouse soleus and frog semitendinosus muscles were isolated and stimulated electrically to produce shortening against external load. The force, muscle length and temperature change associated with these contractions were recorded simultaneously. Efficiency values were worked out from these signals. Our results showed that mouse soleus muscle had a significantly lower efficiency than frog semitendinosus.