Muscle force-length dynamics during level versus incline locomotion: a comparison of in vivo performance of two guinea fowl ankle extensors.

摘要: For a terrestrial animal to move in the complex natural environment, limb muscles must modulate force and work performance meet changing mechanical requirements; however, it is not clear whether this accomplished via collective shift function by all muscles, or division of labor among muscles. Do differ their ability force-length contractile demands different locomotor tasks? We explore question examining vivo guinea fowl Numida meleagris lateral gastrocnemius (LG) digital flexor-IV (DF-IV), during level incline locomotion. During locomotion, LG DF-IV exhibit differing muscle fascicle strain patterns: shortens 10-15% while developing force, whereas undergoes stretch-shorten cycle with large amplitudes small net strains 1-8%. Furthermore, operates at higher stresses (92-130 kPa, compared 23-39 kPa for LG) possesses longer tendon, which allows tendon recover greater elastic energy than tendon. these contribute only one-third expected mass, exhibiting high stride-to-stride variability output. While may allow more economic production, also leads changes output relative timing strain. Thus, primary determinants are mean determinant phase relationship between Our results suggest that, addition influencing muscle's steady morphology affects its capacity mechanism altering tasks.