Proceedings of The Physiological Society

The Biomedical Basis of Elite Performance 2016 (London, UK) (2016) Proc Physiol Soc 35, PC05

Poster Communications

Are there differences in training protocols and racehorse responses of higher- versus lower-ranked trainers?

K. Mukai1, H. Ohmura1, A. Matsui1, Y. Takahashi1, H. Miyata2, T. Takahashi1

1. Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan. 2. Yamaguchi University, Yamaguchi, Japan.


There is great interest from both racehorse trainers and scientists in constructing effective training protocols, however, differences in protocols and the responses of horses to them remain poorly described. The purpose of this study was to investigate training programmes of racehorses in Japan to test the hypothesis that higher-ranked trainers exercise horses differently than lower-ranked trainers. Methods - (1) GPS data loggers on 808 Thoroughbred racehorses from 42 trainers recorded training profiles of each racehorse for approximately one month. (2) Seven well-trained Thoroughbred horses (6 castrated males and 1 female; 488 ± 8 kg) ran on a 6% inclined treadmill to simulate the typical training protocol of higher-ranked (H group, top 20 of 208 trainers; 60% of maximal rate of O2 consumption (VO2max), 90 s; 85% VO2max, 90 s; 110% VO2max, 60 s) or lower-ranked trainers (L group, bottom 100 of 208 trainers; 60% VO2max, 90 s; 85% VO2max, 180 s; 110% VO2max, 30 s), and arterial blood samples were drawn during the final 10 s of the run. Muscle biopsies were taken from M. gluteus medius under local anaesthesia (2% lidocaine, 2 ml/head, s.c.) before, 4 h, and 24 h after the treadmill run, and relative quantitative analysis of mRNA was performed using real-time PCR (3 replicates). Values are means ± SEM. mRNA data were analysed by two-way ANOVA with Tukey's test and the others by paired t-test. Statistical significance was set at P<0.05. Results - (1) Training programmes of H were of shorter distance (1137 ± 30 m) than L (1702 ± 29 m) at moderate-intensity (>6.9 and <13.3 m/s) and longer distance (307 ± 12 m) than L (211 ± 12 m) at high-intensity (>13.3 m/s). (2) Despite shorter total run distance in H (H 2279 ± 21; L 2780 ± 26 m), peak plasma lactate concentration (H 22.8 ± 2.0; L 16.1 ± 2.1 mmol/l), VO2 (H 169 ± 4; L 151 ± 4 ml/(kg×min)) and respiratory exchange ratio (H 1.22 ± 0.02; L 1.13 ± 0.01) in H were higher, and arterial oxygen saturation (H 86.0 ± 0.7; L 89.5 ± 0.8%) and arterial pH (H 7.202 ± 0.018; L 7.275 ± 0.019) in H were lower than in L. Peak heart rate (H 214 ± 3; L 211 ± 4 bpm) and pulmonary arterial temperature (H 41.1 ± 0.3; L 41.1 ± 0.3 °C) did not differ between groups. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) mRNA increased in both groups 4 h after the treadmill run (H 4.81 ± 0.71; L 2.77 ± 0.58 -fold) with H greater than L. Vascular endothelial growth factor (VEGF) mRNA increased 4 h after the treadmill run in H but not L (H 1.79 ± 0.26; L 1.17 ± 0.29 -fold). Conclusions - The training programme of H ran less total distance but greater distance at higher intensity than L, presumably providing greater stimulation of aerobic and anaerobic energy pathways than did L. A single training bout with H induced greater adaptations in mitochondrial biogenesis and angiogenesis of skeletal muscle than with L.

Where applicable, experiments conform with Society ethical requirements