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 5min before and 5, 15, 25, 35, 45 and 60min 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 35min, 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 60min in the pre-training period than the post-training period. These results indicate that aquatraining could improve insulin-glucose metabolism in horses.