Blood lactate disappearance after maximal exercise in trained and detrained horses

The influence of training on blood lactate concentrations during treadmill exercise and a 40-minute inactive recovery period was examined in seven trained and seven detrained thorough-bred horses. Lactate concentrations were measured in venous blood collected at the end of each exercise state, and at intervals for 40 minutes afterwards. Measurements were made of maximum oxygen uptake (V̇O_2max, ml kg⁻¹ min⁻¹), VLA4 (velocity at which blood lactate concentration was 4 mmol litre⁻¹); LA8 (lactate concentration mmol litre⁻¹] during exercise at 8 m sec⁻¹), peak lactate (highest lactate concentration after exercise), LA40 (lactate concentration 40 minutes after exercise), the time of peak lactate concentration (minutes after exercise) and the rate of disappearance of blood lactate (Rt_d). The trained horses had a significantly lower LA8 (2·1 ± 0·1 vs 6·5 ± 1 mmol litre⁻¹, P<0·01), higher VLA4 (9·8 ± 0·2 vs 5·8 ± 0·6 m sec⁻¹, P<0·01) and higher V̇0_2max (156·3 ± 3·8 vs 107·1 ± 3·9 ml kg⁻¹ min⁻¹, P<0·001). The value of Rt_d and the time of peak lactate concentration were not significantly different.