Plasma cortisol and ACTH concentrations in the warmblood horse in response to a standardized treadmill exercise test as physiological markers for evaluation of training status.

Abstract

Reliable physiological markers for performance evaluation in sport horses are missing. To determine the diagnostic value of plasma ACTH and cortisol measurements in the warmblood horse, 10 initially 3-yr-old geldings of the Hannovarian breed were either exposed to a training schedule or served as controls. During experimental Phase 1, horses were group-housed, and half of the horses were trained for 20 wk on a high-speed treadmill. During Phase 2, groups were switched and one group was trained for 10 wk as during Phase 1, whereas the control group was confined to boxes. During Phase 3 horses were initially schooled for riding. Thereafter, all horses were regularly schooled for dressage and jumping, and half of the horses received an additional endurance training for 24 wk. During all phases horses were exposed at regular intervals to various standardized treadmill exercise tests. During and after the tests frequent blood samples were taken from an indwelling jugular catheter for determination of ACTH and cortisol. Treadmill exercise increased both hormones. Maximum ACTH concentrations were recorded at the end of exercise, and maximum cortisol levels were recorded 20 to 30 min later. Except for one test there were no differences in ACTH levels between trained horses and controls. There was no significant effect of training on the cortisol response (net increase) to treadmill exercise in any of the tests during Phase 1. During Phase 2 higher cortisol responses were recorded in controls than in trained horses (P < .05) after 10 wk of training (controls confined to boxes). During Phase 3 plasma cortisol responses were also higher in controls than in trained horses (P < .05 after 6, 18, and 24, P < or = .07 after 12 wk of training) when the inclination of the treadmill was 5%, but not at 3%. There was no overlap in net cortisol responses at 30 min between trained and untrained horses. An ACTH application after 24 wk of training resulted in higher cortisol responses in controls than in trained horses (P < or = .05), without any overlap between the groups at 30 min after ACTH. Plasma cortisol responses to either treadmill exercise or ACTH injection may be a reliable physiological marker for performance evaluation. Prerequisites are sufficient differences in training status and sufficient intensity of exercise test conditions.

Rider and Horse Salivary Cortisol Levels During Competition and Impact on Performance

“…Exercise leads to an increase in cortisol, in humans as well as in horses [19][20][21][22][23][24]. However, by taking saliva samples during a board game competition in Japan, researchers found that changes in salivary cortisol after competition are associated with winning and losing, even if this game does not need physical exercise [25].…”

Glicemia e concentrações séricas de insulina, triglicérides e cortisol em equinos da raça Mangalarga Marchador após exercício físico

“…Os valores de cortisol sérico registrados na presente pesquisa em todos os momentos de avaliação são superiores aos descritos por Marc et al (2000) e Dugat et al (2010), sendo semelhantes aos de Williams et al (2000) somente nos momentos antes e com duas horas após o término do exercício físico. Corroborando com o trabalho de Gordon et al (2007) e Islas et al (2007), os maiores valores na presente pesquisa foram registrados entre 5 e 30 minutos após o término da atividade física, justificando tal fato como resposta aguda frente ao estresse.…”

“…Segundo Hyyppä (2005), sua principal função é prover a biodisponibilidade dos precursores energéticos necessários para manter os esforços musculares através de diversas vias de ação, dentre as quais degradação de proteínas teciduais para liberação de aminoácidos usados na gliconeogênese hepática, mobilização de ácidos graxos livres do tecido adiposo e redução da taxa de utilização celular de glicose. No repouso, Marc et al (2000) citaram intervalo de valores entre 1,47 e 6,73mg/dL e Williams et al (2002) descreveram valores entre 4,5 e 7,5mg/dL. Trabalho mais recente de Dugat et al (2010) cita valores oscilando entre 2,9 e 6,6mg/dL.…”

“…Segundo diversos autores (Marc et al 2000, Islas et al 2007, Mircean et al 2007, Ferraz et al 2010), a mensuração de cortisol sérico poderia ser usada como índice de avaliação de treinamento, pois sua liberação é menor em indivíduos treinados quando comparados aos não treinados quando os mesmos são submetidos ao mesmo tipo de exercício durante o mesmo tempo. Porém, os valores pós-prova são sempre superiores aos encontrados no repouso (Islas et al 2007).…”

Parâmetros hematológicos e bioquímicos em três raças de cavalos de alta performance do Sul do Brasil

“…Respiratory rate and blood lactate are the most sensitive physiological parameters indicating training status (MARC et al, 2000). Lactate metabolism is linked Hematologic and biochemical parameters in three high performance horse breeds from Southern Brazil to glucose metabolism (KANEKO et al, 1997).…”