Plasma lactate and uric acid responses to racing in pacing Standardbreds and relationships with performance

Abstract

Relationships between racing performance and plasma lactate and uric acid concentrations after racing were investigated in pacing Standardbred racehorses. The study was undertaken in order to better understand factors that limit racing performance. Twenty horses were tested after races of 1760 m and 28 horses after races over 2160 m. Blood samples were taken 30-60 min before and 8 and 30 min after a race. There were no significant differences between the race distances for prerace and 8 min postrace plasma lactates. Significant low correlations were obtained for plasma lactate concentration 8 min postrace and the number of race wins (r = 0.29, P = 0.04), number of race placings (1st, 2nd or 3rd; r = 0.34, P = 0.02) and lifetime earnings (r = 0.29, P = 0.04). Net lactate was correlated with the number of race placings (r = 0.31, P = 0.03). There were no significant correlations between performance indices and plasma uric acid concentrations in races of 1760 m. For races over 2160 m, correlations were found between plasma uric acid concentration at 8 min postrace and the number of race wins (r = 0.37, P = 0.06, 95% confidence limits 0-0.65). As well, there was a significant correlation between uric acid concentration at 8 min postrace and lifetime earnings (r = 0.35, P = 0.07, 95% confidence limits 0.06-0.64). Only 10-15% of the variability in retrospective career performance in pacing Standardbreds can be explained by these metabolic markers of the muscle anaerobic response to racing. Plasma lactate and uric acid responses to maximal exercise are unlikely to be useful for evaluating racing performance in pacing Standardbreds in univariate analysis.

Hematologia e bioquímica sérica de equinos de concurso completo de equitação em treinamento

“…1). As menores concentrações de glicose no teste II podem estar relacionadas ao aumento da eficiência na geração e utilização de energia por meio da β-oxidação dos ácidos graxos em função do treinamento, retardando, consequentemente, a depleção dos estoques de glicogênio muscular e hepático e o tempo para fadiga (Nutrient..., 2007 (Snow et al, 1982;Castejón et al, 2006) e em equinos de corrida (Pösö et al, 1993;Räsänen et al, 1996;Evans et al, 2002). Como resultado da degradação do ATP durante o exercício, metabólitos provenientes da degradação dos nucleotídeos derivados da purina, tais como amônia, hipoxantina, ácido úrico e alantoína, aparecem no sangue (Castejón et al, 2006).…”

“…Nos equinos, há predomínio do ácido úrico e da alantoína como metabólitos finais do catabolismo de purina, com suas concentrações máximas observadas 30 minutos após o exercício (Pösö et al, 2004). Räsänen et al (1996) observaram que o aumento na concentração de ácido úrico nos equinos ocorre quando a concentração de lactato excede 12mmol/L, demonstrando que ambos os parâmetros bioquímicos apresentam correlação com o metabolismo anaeróbio (Evans et al, 2002 (Snow et al, 1982). Entretanto, Castejón et al (2006) observaram que, durante o exercício, ocorre aumento dos níveis plasmáticos de creatinina diretamente proporcional à intensidade do exercício realizado, estando esse aumento relacionado à mudança no fluxo sanguíneo renal.…”

“…Segundo Evans et al (2002), o baixo desempenho de equinos atletas pode estar muitas vezes relacionado à limitação fisiológica na produção de energia para o trabalho muscular. A glicose é uma importante fonte de energia para a atividade muscular, entretanto, com o aumento na intensidade do exercício, grande parte da energia é gerada via glicólise anaeróbia, com consequente produção de ácido láctico (Eaton, 1994).…”

The association of various speed indices to training responses in Thoroughbred flat racehorses measured with a global positioning and heart rate monitoring system

“…Distance exercised has been previously found to significantly influence [LA] up to distances of 1600 m (Kubo et al . 1984) but not for distances greater than 1760 m (Evans et al . 2002); it is difficult to completely compare the findings from the current study and previous reports since the horses in the present report were performing a sprint test rather than a submaximal exercise evaluation.…”

Exercise testing in the field

“…34 Twenty horses were tested after races of 1760 meters and 28 horses after races over 2160 meters. 34 Twenty horses were tested after races of 1760 meters and 28 horses after races over 2160 meters.…”