How swimming affects plasma insulin and glucose concentration in Thoroughbreds: A pilot study

Low intensity exercise increases insulin-stimulated glucose uptake in skeletal muscle and decreases its plasma concentration. In this study, plasma insulin and glucose concentrations were evaluated 5 min before and 5, 15, 25, 35, 45 and 60 min after an IV bolus of glucose in 12 Thoroughbreds before and after 1 month of submaximal aquatraining exercise, monitored using heart rate and blood lactate. Plasma glucose concentrations were evaluated using a colorimetric enzymatic method, and plasma insulin concentrations with a solid-phase radioimmunoassay method. Pre-training plasma glucose concentrations at 15, 25 and 35 min, area under the glucose curve and peak glucose concentration were significantly higher than post-training values (P < 0.05). Baseline pre-training plasma insulin concentrations were significantly lower than in the post-training period, and plasma insulin was significantly higher at 45 and 60 min in the pre-training period than the post-training period. These results indicate that aquatraining could improve insulin-glucose metabolism in horses.