Aqua training promotes changes of skeletal muscle mass in show jumping horses

BACKGROUND: The correct prescription of aquatic treadmill training for equine athletes depends on understanding the muscular changes generated by working in the water. AIMS/OBJECTIVES: The aim of this study was to test the hypothesis that the inclusion of a water treadmill in a routine training protocol would alter muscle mass of show jumping horses. METHODS: Six fit-to-compete horses were trained for 10 weeks with a water treadmill (twice a week, 20 minutes, water level at the carpus), in addition to regular physical exercise. Body composition, infrared thermography (IRT) of propulsive muscles (m. brachiocephalic, m. semitendinosus and m. semimembranosus) and field jumping tests for aspartate aminotransferase (AST) and creatine kinase (CK) analysis and kinematic parameters were assessed before and after the protocol. Data was analyzed using paired t-test (p<0.05). RESULTS: Body weight altered (550.5 ± 14.5 vs. 587.0 ± 41.9 kg), related to a fat-free mass gain (485.1 ± 19.1 vs. 520.1 ± 42.2 kg). Fat mass remained unchanged (65.4 ± 11.4 vs. 66.9 ± 10.3 kg), as no significant changes were observed for rump fat thickness (0.69 ± 0.45 vs. 0.59 ± 0.40 cm). IRT temperature of the selected muscles and AST and CK levels increased after training. Improvements in strike power (2.53 ± 0.38 vs. 3.18 ± 0.38 G), take-off angle (20.0 ± 5.0° vs. 24.5 ± 5.4°) and the aerial phase duration (665.3 ± 179.2 vs. 765.3 ± 41.1 ms) for the vertical jumps and in take-off angle (21.7 ± 6.4° vs. 26.1 ± 5.8°) for oxer jumps. CONCLUSIONS: These results suggest that the inclusion of the water treadmill promoted muscular recruitment and gain in muscle mass, contributing to a greater strength in the core muscles, to elevate the forehand, and in the propulsive hind limb muscles, to increase strike power.