Heart Rate, Net Cost of Transport, and Metabolic Power in Horse Subjected to Different Physical Exercises

Considering that workload can also be expressed in terms of estimated net transport cost (COT), the metabolic energy needed to transport unit mass of animal unit distance, the aim of our study was to describe the heart rate (HR), COT, and the total metabolic power requirement per kilogram (P) during different exercises (aerobic, anaerobic, and aerobic-anaerobic exercises). On the basis of their attitude, 25 horses, divided into five equal groups, traveled a distance of 6,000 m, walking at 100 m/min in a horse walker (group A); performed 20-minute treadmill walk at 130 m/min, average speed up gradient of 5% (group B); performed a 700-m-long show jumping course with 13 fences (group C); traveled a distance of 2,100 m galloping at a speed of 700 m/min (group D); and traveled a distance of 2,000 m trotting at a speed of 660 m/min (group E). On each horse, HR was continuously recorded by means of an equine HR monitor. COT was calculated with the following formula: (HR - 35) kg(-1) m(-1) 10(3); P was calculated applying the formula: (HR - 35) min(-1) kg(-1). COT and P values, estimated from the mean HR, measured continuously during each experimental condition showed no linear relationship with HR and speed. The use of combined weight of horse and tack (group C and D) and horse, tack, and sulky (group E) statistically changed the results of formula application. COT and P change in different exercises and provide additional information about performance in athletic horses.