Exercise Training in Obese Horses Decreases Fat Mass Independent of Subcutaneous Fat Thickness
Increasing physical activity is a common recommendation to reduce adiposity and improve insulin sensitivity in obese horses. The present study evaluates the influence of exercise training without dietary restriction on adiposity and basal insulin and glucose concentrations in obese horses. Twelve Arabian geldings (median body condition 8, scale 1-9) were fed hay at 2.4% bodyweight. Four horses remained sedentary (CON) and 8 horses (EX) were exercised 4 times per week for 4 wk at low intensity (30 min trot) followed by 4 wk at higher intensity (10 min trot, 20 min canter, 3° incline) exercise. Prior to and after each training period, basal blood samples, body condition scores, subcutaneous fat thickness (ultrasonic assessment), and total body water (deuterium oxide dilution) were measured. Data were analyzed by the Kruskal-Wallis test and are reported as median (interquartile range). All variables did not change (P > 0.10) in CON throughout the study. In EX, body condition score and subcutaneous fat thickness did not change (P > 0.10). Fat mass calculated from total body water decreased (P < 0.05) from 96 (88-101) kg to 73 (71-78) kg after low intensity exercise and to 61 (57-68) kg after higher intensity exercise. Bodyweight, calculated fat-free mass, and basal glucose and insulin concentrations did not change (P > 0.05) with exercise training. The results of this study demonstrate a decrease in fat mass with exercise training independent of changes in subcutaneous fat thickness, visual appearance of adiposity, or basal glucose and insulin concentrations.