Some Metabolic Effects of Maximal Exercise in the Horse and Adaptations with Training

Abstract

SUMMARY The effects of intermittent maximal exercise (galloping) before and after a 10 week training programme were studied in 6 horses. Determinations were carried out on venous blood for packed cell volume, total plasma protein, glucose, glycerol, free fatty acids, lactate, 11‐hydroxycorticosteroids, blood gases and pH. There were marked changes associated with galloping and some of these could be modified with training. The major findings included (i) an elevated blood glucose, (ii) a large increase in glycerol, which was greatest at 30 min post‐exercise and was higher following training, (iii) smaller increases in free fatty acids following training, (iv) higher levels of lactate after training, (v) a marked fall in pH which was less after training, (vi) an increase in 11‐hydroxycorticosteroids with possibly a more rapid return to resting levels following training. It was concluded that with maximal exercise in the horse both glycogen and free fatty acids served as important substrates for working muscle, and following training greater utilisation of both these substrates occurred. RÉSUMÉ Les effets de galops effectués avant et après un programme d'entrainement de 10 semaines ont étéétudiés chez six chevaux. Les recherches ont porté sur l'hématocrite, les protéines du plasma, le glucose, le glycerol, les acides gras non saturés, les lactates, les 11 cortico steroides, les gaz du sang et le pH. Des changements importants suivirent les épreuves de galop, et ces changements se trouvèrent modifiés par l'entrainement. On trouva en particulier: 1) une élévation du glucose sanguin, 2) une élévation marquée du glycerol, dont le pic se manifestait 30 minutes après l'effort et se révélait supérieur après l'entrainement, 3) une légère augmentation des acides gras après entrainement, 4) une élévation des lactates après entrainement, 5) une chute notable du pH après galop, moindre après entrainement, 6) un accroissement des 11 cortico steroides avec peut‐être un retour plus rapide aux valeurs de repos après entrainement. On conclue que pour l'effort maximum chez le cheval les muscles utilisént comme substrat en particulier les acides gras non saturés et le glycogène. ZUSAMMENFASSUNG Die Auswirkungen einer intermittierenden, maximalen Anstrengung vor und nach einem 10‐wöchigen Training wurde an sechs Pferden untersucht. Gemessen wurden in venösem Blut: Haematocrit, Gesamtprotein, Glucose, Glycerin, freie Fettsäure Laktat, 11‐Hydroxycorticosteroide, Blutgase und pH. Es zeigten sich nach der Galloparbeit deutliche Veränderungen, unter denen ein Teil mit dem Training modifiziert werden konnte. Die wichtigsten Resultate bestanden in a) erhöhter Glucosekonzentration, b) stark erhöhter Glycerinkonzentration mit einem Gipfel 30 Minuten nach Anstrengung; diese Erhöhung war nach der Trainingsperiode ausgeprägter, c) geringeren Erhöhungen der Spiegel freier Fettsäuren nach dem Training, d) höherem Laktatspiegel nach dem Training, e) deutlicher Abnahme des pH, weniger ausgeprägt nach dem Training, f) Erhöhung der 11‐Hydroxycorticoste...

Plasma cortisol concentration in Thorougbred horses during and after standardized exercise tests on a treadmill and effect of conditioning on basal cortisol values

“…It has been stated that measurable increases of plasma or serum cortisol concentration in horses after exercise only occur if exercise load is sufficiently stressful (Thornton 1985). In man this depends on the fitness of an athlete (Kjaer 1996), and it may also hold for horses (Snow and McKenzie 1977;Müller et al 1990;Freestone et al 1991). From the results of the few studies available with sufficient sampling times after exercise it can be deduced that the peak cortisol concentration will normalize within the first 60 minutes af-ter exercise (FlisinskaBojanowska et al 1974;Colborn et al 1991).…”

Stress in the Racing Horse: Coping vs Not Coping.

“…In normal racehorses, a training workout activates the adrenal axis as shown by a rise in plasma cortisol concentrations [4,24]. We have found that there is an immediate and dramatic increase in ACTH and AVP secretion during a 4-5 min burst of maximal exertion [4].…”

Monocarboxylate Transporters and Lactate Metabolism in Equine Athletes: A Review

“…Primarily, it is a useful marker for the estimation of aerobic capacity. It is well known that the trained horses have high aerobic capacity and at a certain absolute work intensity produce less lactate than do horses that are not equally well trained [63,44]. In races, horses perform at maximal intensity and use their anaerobic capacity, as well.…”