Muscle function and tendon adaptation in guinea fowl (Numida meleagris) trained to run on different slopes

Animal movement requires the coordinated interaction of muscle, connective tissue and skeletal elements. Understanding the entire system is necessary to comprehend the mechanics of muscle injury. This system embodies the active, or contractile, component of muscle and a passive component which includes the muscle tendon. Knowledge of the role of both the passive and active elements of skeletal muscles is particularly important as a backdrop to human exercise and stretching protocols that address specific problems such as decreased range of motion or muscle weakness. Utilization of an animal model has allowed me to investigate the role of muscle in vivo during running as well as the response of tendon to long-term exercise.;The first chapter of this thesis describes active length changes which occur in the lateral gastrocnemius and posterior iliotibialis lateralis muscles of guinea fowl during running on different slopes. In vivo measurements revealed that the lateral gastrocnemius underwent very little active length change, however the posterior iliotibialis lateralis underwent extensive lengthening followed by active shortening. This pattern of length change indicates, that during stance, the lateral gastrocnemius acts primarily as a force generator to support the body whereas the posterior iliotibialis lateralis, acts first as a braking mechanism and then as an accelerator.;Chapter two focuses on studies designed to determine the effect of long-term exercise on tendon compliance. Our hypothesis was that the Achilles tendons of guinea fowl completing a long-term training protocol would be stiffer than those of untrained birds. Training consisted of either level or downhill running. Our results indicate that long-term training increases tendon stiffness. Whether training consists of level or downhill running does not appear to influence this outcome.