The Effect of Exercise on Plasma Leptin Concentrations in Horses

• The effect of exercise and training on plasma leptin levels in horses is analysed.
• The effect of exercise depends on the horse's performance.
• Training decreases the leptin level in young, intensively trained horses.
• Plasma leptin level should be monitored, especially in young race horses.

Leptin is an adipokine released by adipose tissue. It regulates food intake, energy expenditure, breeding efficiency and the mood of horses. Exercise can influence leptin secretion via changes in the endocrine profile and energy balance. Several studies which describe exercise induced changes in plasma leptin concentrations in horses gave contradictory results. This paper presents a detailed analysis of the effect of exercise and training on plasma leptin concentrations in horses that underwent various types of physical effort. The effect of exercise depends on its intensity and duration as well as on the horse's sex and performance. Relatively intensive exercise lasting at least 45 minutes increases plasma leptin concentrations in young or irregularly trained horses but not in well trained, performing horses. In well trained horses, plasma leptin concentration does not change during a year, regardless of type of daily exercise. Training decreases the level of this adipokine in young, intensively trained horses and/or neutralizes a tendency for the circulating leptin level to increase in adult horses during a pasture season. Therefore, the level of this adipokine should be monitored, especially in young and intensively trained race horses.