Analysis of work intensity in draft horses based on the heart rate recovery index

So far, no tests have been developed for draft horses to measure their exertion rate. In our study, the heart rate regeneration index was used for the first time to assess the exertion and fatigue of draft horses. A pair of horses was pulling a cart with 12 tourists + a coachman with a total weight of about 1580 kg. The 7-kilometre part the road is uphill in 82%, with an average slope of 4.6%. The control examination of heart rate was performed on horses before transporting tourists, immediately after work and after 10 minutes of rest. The analysis of the horses’ exertion was calculated on the basis of the recovery index, according to the formula (t2 – t3/t2 – t1) × 100%, where t1 denotes the initial heart rate (before exercise), t2 – heart rate immediately after exercise, t3 – after 10 minutes of rest. The following scale of exertion assessment was adopted: group I recovery index <20% – very heavy exertion (long regeneration), group II – recovery index 20.1-50% – heavy exertion, group III – recovery index 50.1-80% – moderate exertion, group IV – recovery index > 80.1% light exertion. Based on the analysis, it was found that the horses’ exertion was: very heavy for 3.3% of horses, heavy for 50%, moderate for 44.8% and light for 1.9% of horses. For about 58% of the horses pulling the carts with full load, this work was a much greater effort compared to the control trials, when the horses pulled „empty” carts without passengers in 2019 (P <0.001). The degree of exertion (fatigue) was the same for horses with a slow pace (76.1 min) and for horses that covered the route at a faster pace (67.6 minutes). The heart rate recovery index is a simple and non-invasive measure of exertion (fatigue) of horses and their adaptation to the work performed and can be used both to assess the preparation of horses for work and their welfare.