Muscle morphology heterogeneity: control, significance for performance and responses to training

Abstract

The skeletal musculature of the horse is highly developed and adapted to match the animal's athletic potential. More than half of a mature horse's body weight comprises skeletal muscle and the total muscle blood flow during maximal exercise represents 78% of total cardiac output. Exercise requires the co–ordinated application of many different body systems under the control of the nervous systems. Metabolites and oxygen reach skeletal muscle fibres via the respiratory, cardiovascular and haematological systems. The muscle fibres produce energy in the form of ATP that, via the contractile machinery, is converted into mechanical work. The structural arrangements of the musculoskeletal system provides the means with which to harness this energy to move the horse's limbs in a characteristic rhythmical pattern that is well established for each gait.Equine skeletal muscle is considerably heterogeneous and this diversity reflects functional specialisation and is the basis of its adaptive plasticity. Cellular and molecular diversity of equine muscle and the response of this tissue to exercise and training have been studied extensively over the past 30 years.