Water treadmills are gaining in popularity for use with horses, with researchers finding that high water levels must be used for effective slow-speed conditioning.
North American researchers used 15 client-owned Quarter horses, all competitive barrel racers, in a study to learn more about the workload, in particular the effect of speed and water height.
Water treadmills have historically been used in human athletic training as well as rehabilitation, and are gaining popularity in the equine veterinary world. They produce low-impact, high resistance work with the ability to minimize concussive forces.
Water treadmills are primarily designed for rehabilitation but in practice are also being used for conditioning.
Despite their popularity for conditioning horses, the intensity of water-treadmill exercise has not been well documented.
“To our knowledge, there are currently no protocols available for conditioning horses on them,” Persephone Greco-Otto and her colleagues reported in the journal BMC Veterinary Research.
“Instead, conditioning is reliant on the experience and ability of the operator to gauge fatigue.”
To develop effective conditioning protocols, the effect that water height and treadmill speed on workload must be better understood.
“Water height dictates intensity of exercise, since increased water height results in increased resistance to limb movement,” the study team from the University of Calgary and Washington State University said.
However, this is only true up to a certain point – above waist-deep water in humans, metabolic demand begins to decrease, as shown by decreased oxygen consumption.
“This is because as submersion increases, resistance is partly counteracted by increased buoyancy.
“While it appears that optimal conditioning occurs when the water is at mid-thigh height for humans, an optimal water height has not been determined for horses.”
The goal of their study was to determine the effects of water height and speed on exercise intensities, based on cardiac and respiratory measurements, for horses walking on a water treadmill.
The horses, aged 11 to 15, were all of similar size and had been assessed as sound.
The horses’ cardiac and respiratory performance were measured across three speeds and three water heights. A dry treadmill was used as the control.
The walking speeds deemed to be appropriate for all horses were 1.11, 1.25, and 1.39 metres per second. Water height was set for each horse using anatomical landmarks – mid-cannon, carpus and stifle.
Water height and its interaction with speed had a significant effect on the horse’s workload, based on oxygen consumption, breathing levels and heart rate.
Respiratory frequency peaked with water at the mid-height (the carpus) at the highest speed of 1.39 metres per second.
Water height had a greater impact on exercise intensity than speed.
“At the lowest workload conditions, horses were more erratic with their breathing, probably because the work was not sufficient to ‘force’ them into a more rhythmic or controlled breathing strategy that reflects the level of energy expenditure,” the researchers said.
“Heart rate peaked at the greatest water height and fastest speed (stifle height water level and 1.39 m/s), indicating that these conditions probably created the greatest workload.”
Blood lactate concentrations were also measured to help assess the intensity of water treadmill exercise. Values remained low throughout all conditions, they reported.
They continued: “This study found that the presence of water, and the height of that water, had the most significant effect on workload, as measured by oxygen consumption.
“For horses to achieve sufficient workloads on water treadmills, the present study shows that protocols at slow speeds must incorporate high water levels,” they said, adding that the effect of the length of exercise was not examined, and its effect on conditioning is not known.
Further research on the effects of water-treadmill conditioning protocols on the athletic fitness of horses was necessary to provide further evidence-based guidelines about their use, they said.
The study team comprised Persephone Greco-Otto, Stephanie Bond, Grace Kwong and Renaud Léguillette, from the University of Calgary; and Raymond Sides and Warwick Bayly from Washington State University.
Workload of horses on a water treadmill: effect of speed and water height on oxygen consumption and cardiorespiratory parameters
Persephone Greco-Otto, Stephanie Bond, Grace P. S. Kwong, Warwick Bayly and Raymond Sides, Renaud Léguillett.
BMC Veterinary Research, 2017 13:360 https://doi.org/10.1186/s12917-017-1290-2