Effects of warm-up intensity on kinetics of oxygen consumption and carbon dioxide production during high-intensity exercise in horses

Abstract

Objective - To compare effects of low and high intensity warm-up exercise on oxygen consumption (V•o2) and carbon dioxide production (V•co2) in horses. Animals - 6 moderately conditioned adult Standardbreds. Procedures - Horses ran for 2 minutes at 115% of maximum oxygen consumption (V•o2max), 5 minutes after each of the following periods: no warm-up (NoWU); 10 minutes at 50% of V•o2max (LoWU); or 7 minutes at 50% V•o2max followed by 45-second intervals at 80, 90, and 100% V•o2max (HiWU). Oxygen consumption and V•co2 were measured during exercise, and kinetics of V•o2 and V•co2 were calculated. Accumulated O2 deficit was also calculated. Results - For both warm-up trials, the time constant for the rapid exponential increase in V•o2 was 30% lower than for NoWU. Similarly, the rate of increase in V•co2 was 23% faster in LoWU and HiWU than in NoWU. Peak values for V•o2 achieved during the high-speed test were not significantly different among trials (LoWU, 150.2 ± 3.2 ml/kg/min; HiWU, 151.2 ± 4.2 ml/kg/min; NoWU, 145.1 ± 4.1 ml/kg/min). However, accumulated O2 deficit (ml of O2 equivalents/kg) was significantly lower during LoWU (65.3 ± 5.1) and HiWU (63.4 ± 3.9) than during NoWU (82.1 ± 7.3). Conclusions and Clinical Relevance - Both the low-and high-intensity warm-up, completed 5 minutes before the start of high-intensity exercise, accelerated the kinetics of V•o2 and V•co2 and decreased accumulated O2 deficit during 2 minutes of intense exertion in horses that were moderately conditioned.