In order to gain insight into several mechanical properties of skeletal muscle where expected performance levels are exceeded and cannot be accounted for in the context of current paradigms of muscular contraction, several experiments were conducted on varying physiological levels using amphibian skeletal muscle. Using single muscle fibres in vitro, it was found that there is a small, but systematic, steady-state force enhancement on the ascending limb of the force-length relationship that can exceed (for specific stretch conditions) the maximal isometric forces obtained at optimal fibre length. This force enhancement is difficult to reconcile within the framework of the sarcomere length non-uniformity theory, and it was not associated with an increase in the passive force following stretch of activated fibres.

During frog jumping, it was found that the high power output of one of the major jumping muscles (plantaris longus-PL) is achieved by a decoupling of fascicle and muscle-tendon complex shortening as proposed by Roberts and Marsh (2003). The decoupling is achieved through a "catch" mechanism reminiscent of that seen in insects and the mantis shrimp, except that the catch is not provided by a physical constraint but by an intricate change of the mechanical advantage of ground reaction and PL force about the ankle in the propulsive phase of jumping. Furthermore, the catch mechanism plays and increasingly important role with increasing jump distance. The magnitude of the catch is modulated by force production and muscle-tendon unit lengthening early in the propulsive phase of the jump.

Several tests of PL were conducted in situ in which muscle-tendon unit and fascicle disparities were reproduced early in the propulsive phase which is characteristic of a catch mechanism and that catch magnitude increased as the delay for plantaris shortening was increased. Contractile characteristics of PL such as the disparity between muscle-tendon unit fascicle lengths and speeds of shortening were also investigated in situ which are likely a result of a change in the angle of pennation of the fibres, shortening of aponeuroses, and shortening of elastic structures after peak force occurrence.