What is fatigue?
Muscle fatigue is a reduction in the ability of skeletal muscle to perform the expansions and contractions required for locomotion. The strength and speed of muscular contractions determines the maximal velocity and duration of exercise. Fatigue has serious implications on performance, length of recovery, and if chronic, potentially duration of a racing career. Furthermore, this lack of muscular control can initiate a cascade of events with welfare implications for both the horse and jockey.
Causes of fatigue include;
- Lactic acid accumulation, which inhibits energy metabolism and muscular excitation required for contraction and expansion of muscle fibres.
- Accumulation of metabolic waste (ammonia) within skeletal muscle tissue affects control over muscular function and oxidative (aerobic) capacity during sub-maximal exercise.
- Depletion of muscle glycogen stores (referred to as ‘hitting the wall’) results in the use of alternate, slower release energy sources.
- Excessive water an electrolyte losses via sweat and urine adversely impact on blood volume and perfusion of muscles, energy production and utilisation, nerve and muscular function.
- Fatigue induced lameness may impact on control over a horse’s stride, placing abnormal pressure and strain on muscles, bones, tendons and ligaments.
- A diet that is deficient in B-Group vitamins may result in a suppressed appetite, reduced energy and protein utilisation.
- The onset of fatigue may result in failure to finish and present a significantly increased risk to the health of both the horse and jockey.
Superior racing performance of Thoroughbreds and Standardbreds has been correlated with a high oxygen carrying capacity and reduced lactate accumulation during sub-maximal exercise
How can fatigue be minimised?
- A high quality protein source such as Power Formula® is required to maintain and build muscle strength and size for more efficient locomotion during a race. Increased efficiency may reduce the reliance on muscle glycogen, reduce lactic acid production and delay the onset of fatigue.
- The combined use of Ranvet’s Equitone® and Muscle-E® provide an instantly available energy source, reduced free radical damage of muscle cells through the provision of powerful antioxidants, enhanced absorption and utilisation of iron to maximise the oxygen carrying capacity of hemoglobin for improved aerobic capacity.
- Physical training to increase stroke volume, haemoglobin concentration, muscle capillarity and total blood volume for improved aerobic energy utilisation and reduced lactic acid production (e.g. long, slow distance exercise).
- Training horses >80% VO2 max, (90% of maximal HR) has been found to increase the percentage of fast twitch fibres (for anaerobic/sprint exercise) and enhanced buffering capacity of exercised muscle.
- Light exercise prior to racing has been found to significantly increase the time to fatigue by maximising the oxygen uptake of muscles and subsequently reducing the reliance on stored muscle glycogen.
- Drenching with Salkavite® will increase the levels of electrolytes and B-Group vitamins required for energy utilisation, nerve and muscular function, in addition to initiating a thirst reflex and the intake of fluids.
- Ensure muscle glycogen stores are maintained prior to exercise through adequate carbohydrate provision.
- Provision of Aminovite PLUS® provides a daily supply of B-Group vitamins which are required for blood formation, energy and protein utilisation. (Please note that B-Group vitamins are water soluble and therefore require daily supplementation).
- The use of body acid neutralisers such as Ranvet’s Neutrolene® range replace sodium ions lost in sweat and buffer the acidity of lactic acid produced during high intensity exercise.
Carbohydrate loading just prior to exercise has no proven scientific efficacy
- Lewis, L. ‘Equine Clinical Nutrition: Feeding and Care’ Kansas (1995)