[Comparison of the compliance of resting and contracting muscle].

Frog sartorius muscles are stretched at rest and during maximal tetanic contractions. Parallel compliance decreases when the length increases. The relationship between compliance and length is linear in double-logarithmic scale. The compliance of the active muscle (tetanic contraction) is not related to the length. The series-compliance is calculated from the parallel compliance and the active one. It increases with the length of muscle. These results are discussed on the basis of the sliding-filaments theory.