Effects of treadmill inclination on kinematics of the trot in Dutch Warmblood horses.

The research study investigates how uphill trotting on a treadmill impacts the stride characteristics of well-trained Dutch Warmblood horses. It also measures whether additional weight, in the form of a rider or lead, induces further or different modifications than the incline alone. Heart rates, stride and stance duration, and joint (particularly fetlock and tarsal) extensions are found to react differently to inclined and flat surfaces.

Methodology and Study Design

• Six well-trained Dutch Warmblood horses were used in the study. They undertook trotting exercises at a speed of 4 m/s on a standard (horizontal) treadmill and then on an inclined (6%) treadmill.
• The study conditions were divided into three categories – unloaded (no extra weight), mounted by a competent 90 kg rider, and loaded with 90 kg of lead. These conditions were established to evaluate whether extra weight induced more or varied modifications compared to the incline itself.

Key Findings

• In all three conditions, increased heart rates were recorded on the inclined treadmill compared to the horizontal one, signifying that incline trotting demands more effort.
• Stride duration showed a tendency to increase on the inclined treadmill, though it’s not explicitly stated if this difference is statistically significant.
• The study found that the length of time each foot kept in contact with the ground (stance duration) increased significantly on an inclined surface, much more so in the hindlimbs than the forelimbs.
• In the unloaded condition, the maximum extension of the joint connecting the horse’s leg and hoof (fetlock) in the forelimb decreased on the incline, suggesting a reduced stride length.
• Tarsal (ankle joint) range of motion and maximum fetlock extension of the hindlimbs, conversely, increased significantly on the inclined treadmill in all three conditions. This suggests the hindlimbs played a more essential role in both supporting weight and propulsion when trotting uphill.

Conclusions and Implications

• The research concludes that uphill trotting leads to changes in the movement and work distribution in a horse’s body. Specifically, it seemed the hindlimbs had to carry more weight and provide more propulsion when trotting uphill.
• These findings underline the importance of training practices that mimic competition conditions, e.g., varied terrains, to ensure horses develop necessary strength and agility in the right muscles.
• The research could also be relevant to equine medical and therapy fields, as understanding limb load distribution may help diagnose and treat movement or loading issues in horses.