Meeting Abstract
The ability of the locomotor muscles to effect both economical transport and powerful bursts of activity is necessary for survival in many species. However, specialization in either of these performance traits is expected to negatively impact the other due to functional constraints in muscle design, resulting in a performance trade-off. The muscular power versus economy trade-off has traditionally been explained by muscle fiber type composition. Although fiber type plays an undeniable role in performance specialization, differences in muscle architecture may also determine the economy and power of a muscle. Muscles with longer fascicles, composed of more in-series sarcomeres, are capable of faster shortening velocity, allowing for increased power production. However, long fascicles are expected to reduce economy because, for a given force production, more energy-consuming contractile units must be activated. We hypothesized that longer muscle fascicle length is positively correlated with both power production and increased locomotor cost. In a set of 11 power- and 13 endurance-trained athletes, we measured 1) gastrocnemius lateralis (GL), gastrocnemius medialis (GM), and vastus lateralis (VL) muscle fascicle length via ultrasound, 2) maximal power production during cycling and countermovement jumps, and 3) running cost of transport. We found that longer fascicles in GL and GM are positively correlated with both cycling and jumping power, and that longer GL fascicle length is directly correlated with increased cost of transport. These results are consistent with the hypothesis that, at least for certain muscles, fascicle length plays a significant role in the performance trade-off between power and economy.
