Heart rate and blood lactate responses during exercise in preparation for eventing competition

The aim of this study was to investigate the heart rate and blood lactate responses to exercise in event horses in normal training, and to compare them to those encountered in eventing competition. It was hypothesised that the responses during exercise in the course of training for CCI*** events would be significantly different from those of the Cross-Country day. Heart rates and blood lactate concentrations were measured in 13 elite event horses after intense exercise sessions conducted during the late stages of preparation for CCI*** or CCI**** 3-day-event competition. Mean +/- s.d. heart rate during exercise was 138 +/- 17 beats/min and mean blood lactate concentration after exercise was 1.0 +/- 0.6 mmol/l. These values were compared to heart rates and blood lactate concentrations recorded during and after a CCI*** Cross Country course using unpaired t tests (unequal variances) and 99.9% confidence interval analysis. Mean heart rates during and blood lactate concentrations after the competition were 195 +/- 8 beats/min and 10.2 +/- 4.2 mmol/l. The 99.9% confidence intervals were 183-207 beats/min and 7.7-12.6 mmol/l. Heart rates and blood lactate concentrations recorded during exercise sessions were significantly lower than competition values (P<0.001) and lay outside 99.9% confidence intervals for most horses. Only one horse achieved heart rates and blood lactate concentrations during exercise sessions that were similar to those occurring in competition. The intensity of exercise during normal training sessions was much lower than during competition, suggesting that many event horses are not appropriately trained.