Changes in muscle activation with graded surfaces during canter in Thoroughbred horses on a treadmill.
Authors: Takahashi Yuji, Takahashi Toshiyuki, Mukai Kazutaka, Ebisuda Yusaku, Ohmura Hajime
Journal: PloS one
Summary
# Editorial Summary: Muscle Activation During Graded Canter Work in Thoroughbreds Researchers measured electromyographic activity across 12 forelimb and hindlimb muscles in seven Thoroughbreds cantering at 10 m/s on a treadmill set to grades ranging from -4% to +8%, seeking to clarify how surface inclination influences neuromuscular demands during the primary training gait. Stride duration shortened significantly on the steepest 8% grade due to reduced swing phase duration, whilst gentle inclines of ±4% produced negligible changes in spatiotemporal parameters. Steep uphill canter (8%) triggered marked increases in muscle activation during both stance and swing phases—notably 47% greater activity in the biceps femoris and 54% in the triceps brachii during swing, alongside 29% elevation in gluteus medius activation during stance—whereas moderate grades elicited no meaningful neuromuscular response. These findings suggest that training protocols incorporating steep inclines may selectively target muscles responsible for propulsion and stride frequency, offering farriers and conditioning professionals a practical tool for targeted strengthening; however, the narrow range of moderate grades (±4%) appears insufficient to stimulate meaningful adaptations, implying that intentional incline work must exceed 4% to constitute a distinct training stimulus.
Read the full abstract on PubMed
Practical Takeaways
- •For training Thoroughbreds: include 8% uphill canter work to elicit measurable increases in propulsive muscle activation and potential strength gains; gentler slopes (4% or less) provide minimal additional stimulus beyond flat work
- •Farriers and veterinarians should recognize that steep uphill work (8% grades) fundamentally alters stride mechanics and muscular demands compared to flat or mild slopes, which could influence training progression and injury prevention strategies
- •When designing hill training protocols, use 8% as a minimum threshold to achieve neuromuscular adaptations; shallow grades may be useful for recovery or warm-up but won't provide significant conditioning stimulus
Key Findings
- •Stride duration significantly decreased on 8% uphill grade due to shorter swing duration (P < 0.001), with no changes at -4% or 4% grades
- •On 8% uphill grade, stance phase muscle activation increased significantly in five muscles, with gluteus medius (+29%) and biceps femoris (+47%) showing largest increases
- •Swing phase muscle activation increased in six muscles on 8% grade, with triceps brachii (+54%) and semitendinosus (+51%) showing greatest increases
- •Grades of ±4% produced minimal neuromuscular effects, suggesting 8% uphill canter may be threshold for meaningful muscle strengthening stimulus