Time of feeding and fat supplementation affect plasma concentrations of insulin and metabolites during exercise.

The research article is about the impact of meal time and fat supplements on blood insulin and metabolite levels during exercise in horses. The findings showed that feeding horses 3 hours prior to exercise elevated glucose and insulin concentrations while seeming to lower fat oxidation during exercise.

Study Design

• The study utilized six Thoroughbreds to explore how feeding times can alter exercise responses in horses receiving either a regular textured feed or a fat-supplemented textured feed.
• Three horses were given a fat-supplemented diet while the other three were given a standard control ration of textured feed.
• The horses were put through a standardised exercise test (SET) on a high-speed treadmill at three different times: after a 12-hour overnight fast, 3 hours after feeding, and 8 hours after feeding.

Exercise and Blood Sampling

• The SET included various phases of walk, trot, and gallop.
• Blood was sampled from the horses’ jugular veins before feeding, on an hourly basis until the SET began, at the end of each exercise step, and 15 & 30 minutes post-exercise.
• The exercise-induced heart rate and levels of blood glucose, lactate, insulin, and non-esterified fatty acids (NEFA) were recorded.

Key Findings

• When the horses were fed 3 hours prior to exercise, elevated concentrations of plasma glucose, and insulin were observed at rest.
• These increased insulin concentrations decreased plasma glucose levels during exercise.
• The higher insulin levels seemed to inhibit fat oxidation during exercise, as horses that were either unfed or had been fed 8 hours prior had a net disappearance of NEFA in the plasma during exercise.

Conclusion

• The research implies that starting an exercise with increased plasma insulin levels brought no advantages during the exercise conducted in the experiment.