Comparison of the effects of fructose and glucose supplementation on metabolic responses in resting and exercising horses.

The study investigates the effects of fructose and glucose supplementation on the metabolic responses in resting and exercising horses. This research determined that glucose supplementation significantly increased glycaemic and insulinaemic response in resting horses, while fructose showed no obvious advantages.

Methodology

• Five trained horses were fed two different carbohydrate sources (fructose and glucose) in a randomized sequence.
• The horses received the supplements both at rest and before or during exercise.
• The resting regime was formed of 0.6 kg grass meal pellets (control) or 0.6 kg grass meal pellets supplemented with either 50% glucose or 50% fructose.
• The exercise regime contained 0.3 kg grass meal pellets supplemented with either 50% glucose or 50% fructose fed before or during simulated endurance exercise on a treadmill.
• The treadmill exercise lasted 120 minutes, including a 15 minutes rest period after 60 minutes of running time.
• Blood samples were collected from horses for glucose, insulin, free fatty acids, and lactate analysis.

Findings

• In resting horses, glucose supplementation resulted in a significantly higher glycaemic and insulinaemic response than the control or fructose feedings.
• Plasma glucose levels were significantly higher after glucose supplementation given before or during exercise.
• Similar plasma glucose levels were observed when fructose was given before exercise, whereas fructose supplementation during exercise yielded a lower glycaemic response than glucose feeding.
• While plasma insulin, free fatty acid, and lactate levels changed in relation to exercise, the chosen treatment did not alter these results.

Conclusion

• During simulated endurance exercise, plasma glucose concentrations were higher after glucose feeding, with no counter-regulation by insulin observed.
• The greater glycaemic response could be beneficial, as exogenous glucose can function as an energy source during lengthy exercise periods.
• Contrary to glucose supplementation, fructose showed no clear advantages as a carbohydrate source for exercising horses.