The Effect of Land and Underwater Treadmill Training on Metabolic Responses to Exercise and Properties of Superficial Digital Flexor and Gluteal Muscle

Abstract

Introduction Resistance training provided by underwater (UWT) treadmills may enhance strength and fatigue resistance of superficial digital flexor muscle thereby reducing tendon injury. This study examined effects of UWT and land (LT) treadmill training on SDF and gluteal muscle. Methods Six unfit horses (3???2 crossover design, 60d detraining period) walked on UWT and LT for 5d/week for 8 weeks (up to 40?min/day). A standardized exercise test (SET) was performed 2 weeks before, and after L or UW training, and V180?bpm and La10.5?m/s calculated. Resting and post-SET gluteal and SDF muscle biopsies were obtained. Muscle [glycogen], [lactate] and [ATP], fiber type composition and min/max fiber diameters were analysed. Comparisons were made using GLM or ANOVA, mean?±?SD and significance of P<0.05. Results Post-exercise SDF muscle lactate increased 3?4 fold to 30?±?12 (UWT) and 41?±?15 (LT) mmol/kg dw post-exercise. Post-exercise gluteal muscle lactate increased 2 fold to 55?±?18 (UWT) and 62?±?18 (LT) mmol/kg. No significant differences were found between UW and L post-exercise muscle [glycogen], [lactate] and [ATP], V180 or LA10.5 or fiber type composition. Gluteal fiber diameters decreased significantly with UW and L training. Fiber diameters in SDF muscle decreased with training to a significantly lesser extent after UW vs. L training. Conclusions At maximal speed, both SDF and gluteal muscle have a significant anaerobic response which was not impacted by UWT or LT training at a walk. UWT may be of benefit by attenuating the training induced decrease in fiber sizes in SDF muscle thereby enhancing SDF muscle strength. Ethical Animal Research All procedures were approved by the Institutional Animal Care and Use Committee of the University of Minnesota. Sources of funding:?Supported by University of Minnesota Equine Center with funds provided by the Minnesota Racing Commission, University of Minnesota Agricultural Experiment Station, and private donors. Competing interests:?none.