Effect of Water Depth on Limb and Back Kinematics in Horses Walking on a Water Treadmill.
Authors: Tranquille Carolyne, Tacey Jack, Walker Victoria, Mackechnie-Guire Russell, Ellis Julie, Nankervis Kathryn, Newton Richard, Murray Rachel
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Water Depth Effects on Equine Water Treadmill Kinematics Water treadmill rehabilitation is commonplace in equine practice, yet practitioners have limited evidence on how to optimise water depth for specific therapeutic goals. Tranquille and colleagues fitted six mature horses with inertial measurement units and motion-capture markers to simultaneously track limb and spinal kinematics whilst walking at a standardised speed (1.6 m/s) across five water depths ranging from dry to 47 cm. Carpal and tarsal joint flexion increased non-linearly with water depth (P < 0.0001), alongside progressive gains in thoracic spine range of motion and substantial increases in sacral and pelvic mobility in both dorsoventral and mediolateral planes (P < 0.001). The data reveal a biomechanical threshold effect—horses responded consistently to modest depth increases until reaching a plateau—which has clear implications for designing water treadmill programmes, particularly when targeting specific spinal segments or managing pelvic stability. Practitioners should recognise that depth selection meaningfully alters the neuromuscular demands imposed, suggesting water depth warrants deliberate prescription rather than arbitrary application if rehabilitation goals centre on particular anatomical structures or movement patterns.
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Practical Takeaways
- •Water depth significantly alters limb and spinal kinematics during treadmill exercise; modest depth increases (even 7.5 cm) produce measurable biomechanical changes that should be considered when designing rehabilitation protocols
- •A threshold water depth exists beyond which additional depth produces diminishing returns on kinematic changes; practitioners should identify optimal depth for individual rehabilitation goals rather than assuming 'deeper is better'
- •Increased pelvic mobility at greater depths may benefit some rehabilitation scenarios (e.g., sacroiliac mobility) but could be problematic for others; depth selection should be tailored to the specific condition and training objective
Key Findings
- •Carpal and tarsal flexion increased nonlinearly with water depth at swing phase (P < 0.0001)
- •Thoracic spine flexion-extension ROM increased significantly at all thoracic sites with increasing water depth (P < 0.0001)
- •Sacral and tuber coxae dorsoventral and mediolateral ROM increased significantly with water depth (P < 0.001)
- •Biomechanical response plateaued at a threshold water depth with increased pelvic roll observed