Influence of the Fascicle Length and Physiological Cross-sectional Area of M. soleus on Ankle Joint Kinetics

It is crucial for athletes and coaches to assess type of movements for which their physique (e.g., tall-and-slender or short-and-thick) is suited. This assessment is especially valuable for sports activities in which competitors are classifi ed by body mass (such as weight lifting, boxing, wrestling, judo, etc.), as the amount of muscle mass that the athletes can gain through strength training is limited in these cases. The maximal isometric force development capability of a muscle is a linear function of its physiological cross-sectional area (PCSA). The coeffi cient of the linear function is referred to "specifi c tension" (Close 1972; Fukunaga, Ito, et al., 1996). This relation can be expressed as Fisom = SPT * PCSA, where Fisom is maximal isometric force and SPT is specifi c tension. In general, the greater the PCSA is, the greater the expected isometric force development. However, when considering the mechanical output of muscles during movement, another factor, the length of muscle fascicles, exerts an important infl uence. This is due to the force-length-velocity relation of muscles (Edman 1988; Lieber 2002). When considering a situation in which the muscle volume (thus the muscle mass) is given, it is not clear which of the following is more advantageous: to have Infl uence of the Fascicle Length and Physiological Cross-sectional Area of M. soleus on Ankle Joint Kinetics