Effects of exercise intensity and duration on plasma beta-endorphin concentrations in horses.

The research investigates the impact of different exercise intensities and durations on the levels of beta-endorphin—a type of hormone—in horses. The findings suggest that the beta-endorphin concentration in horses differ considerably under various exercise circumstances, with higher intensities yielding more significant concentrations.

Research Methodology

The study involved eight mares with a mean age of six years, and an average body weight of 450kg. These horses underwent exercise sessions at two intensity levels:

• 20 minutes at 60% of their maximum oxygen consumption (VO2 max)
• Up to the point of fatigue at 95% of their VO2 max

Plasma beta-endorphin (EN) concentrations were assessed at different intervals during and after these exercise sessions. Plasma glucose concentrations were also measured at the same time intervals, with an added measurement of plasma lactate concentration taken five minutes after the session.

Findings

It was observed that the highest beta-endorphin concentrations were recorded within 0 to 45 minutes after the horses finished an exercise session. It was also established that the exercise’s intensity and duration significantly affected beta-endorphin concentrations in these horses. The levels of beta-endorphin were notably higher after exercise at 95% VO2 max than after 20 minutes of exercise at 60% VO2 max.

However, no significant correlation was found between beta-endorphin concentration and lactate concentration. Nevertheless, a weak but significant correlation was detected between beta-endorphin concentration and glucose concentration in the exercises executed at both intensities.

Conclusions

The research concluded that there exists a critical exercise threshold for beta-endorphin concentration in horses, which aligns with 60% VO2 max or less and depends on the exercise’s duration and intensity. The study also emphasized that controlled exercises can result in significant differences in beta-endorphin concentrations between horses, making it questionable to make horse comparisons based on their beta-endorphin levels.