ISSN 2398-2977      

Musculoskeletal: training surfaces and regimens - racehorses

pequis

Track surfaces and design

  • Track surface and design are two of many factors that can contribute to, or prevent, injury during racing.
  • Other factors include:
    • Age, eg skeletal maturity.
    • Conformation. 
    • General health and fitness. 
    • Training regimen. 
    • Previous injury. 
    • Subclinical injury. 
  • No studies have defined the optimal surface structure and track layout to minimize injuries. 
  • Research has been hampered by:
    • Confidentiality concerns among participants.
    • Inconsistant definitions of injury and breakdown between studies. 
    • Insufficient numbers to obtain statistical significance.
    • Need for preliminary biomechanical and gait analysis research to determine effects of changes in racetrack surfaces and geometry.

Patterns of injury associated with track design

  • Higher incidence and severity of injury during racing compared to training.
  • Injuries can vary between tracks because of differences in track surface and design. 
  • Majority of injuries occur around the final turn:
    • At fatigue stage of race. 
    • An area of high traffic → impacted surface → decreased cushion. 
    • Distal limb fractures predominate - 75% of all injuries. 
  • 32% of racing horses experience an injury that alters training or racing program. 
  • Sites of injury evident radiographically:
    • Carpus - 72%. 
    • Metacarpus - 42%. 
    • Fetlock - 85%.

Track surface characteristics

  • Qualities studied include:
    • Moisture. 
    • Composition, eg organic matter. 
    • Strength, eg compaction (increased shearing strength) and penetrability or 'cushioning'. 
    • Co-efficient of friction between the hoof and track surface.

Moisture

  • Primary influence on turf track surface. 
  • Optimal levels = close to saturation. 
  • Varies significantly around a track, on different days, as well as between tracks. 
  • Determined by weather but can be varied artificially by water management strategies.
  • Muddy tracks associated with higher incidence of injury than sloppy or fast tracks.  

Check moisture content at different parts of the track.

Wetting sand decreases its cushioning effect.

Organic matter

  • Second to moisture in influence on track surface.
  • Enhances moisture retention. 
  • Decreases dust.
  • Decreases soil compaction. 
  • Increases 'sponginess'.
  • Increases drying time. 
  • Increases 'stickiness'.  

Add peat to increase organic composition. May need to be regularly replaced.

Compaction

  • Depth of sand more important than moisture content on dirt tracks. 
  • Occurs in high-traffic areas, eg starting chutes, access areas.
  • Associated with higher incidence of breakdown injuries.
  • Particular problem with soil or dirt tracks. 
  • Varies seasonally, possibly related to moisture content.
  • Ensure maintenance and other vehicles access track nearer the starting positions, ie before fatigue occurs, or use a part of the track where minimal racing occurs. 
  • Increased cushioning occurs close to rail due to run off and erosion from the 'crown' of the track.  

Monitor particle distribution and cushion depth regularly.

Turf versus dirt

  • Turf generally associated with lower incidence of injury.
  • In the UK, where turf tracks for flat racing predominate, the incidence of catastrophic injury is 0.08% of starters. 
  • In the USA, where dirt tracks predominate, the incidence of catastrophic injury is 0.143% of starters.

Speed

  • Hard tracks are 'faster'. 
  • Faster race times on hard tracks increase the incidence of severe injuries, especially carpal fractures. 
  • Increasing depth of sand or moisture content will slow the track. 
  • Increased track preparation, eg harrowing → more uniform gait and leg action → reduced incidence of injury.

Monitoring track characteristics

  • Check cushion depth to avoid build up of soil at track edges.
  • Moisture content on turf tracks should be close to saturation.

Banking

  • Banking, or 'super-elevation', describes the radial slope of the track as it goes through a curve. 
  • The goal of banking is to counteract the centrifugal force acting on the horse as it runs at speed around the curve. 
  • A transition to the optimal degree of banking is necessary going in and out of the turn, ie a gradual increase in banking from the straight to the center of the curve (maximal banking), an even degree of banking through the true curve, then a gradual decrease out of the curve back into the straight. 
  • One estimate of the optimal degree of banking is 42%, ie 42 cm slope in every 100 cm track width. 
  • Underbanked semicircular curves → gait asymmetries:
    • Horses lean towards the center of the curve and shift hindquarters outwards.
    • Difference in width of the two diagonal forelimb to hindlimb distances. 
    • Associated with abnormal fetlock movement.
    • Associated with differences in temperature of left and right limbs after exercise.
    • May increase risk of lameness. 
  • An increase in the degree of banking of the turns results in decreased injury and lameness rates after racing in Standardbred horses Standardbred.
  • Banking is probably important on thoroughbred tracks also, although competitors tend to concentrate near the rail, in a relatively flat portion of the track.  

Confine training runs to the outer half of the track, which may then have a reduced degree of banking.

Training regimens

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Racehorse training

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Harness racing

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Birch H L & Goodship A E (1999) Can appropriate training regimes reduce the incidence of skeletal injury and loss of horses from training? Equine Vet Educ 11 (6), 310-313 VetMedResource.
  • Evans D L & Walsh J S (1997) Effect of increasing the banking of a racetrack on the occurrence of injury and lameness in Standardbred horses. Aust Vet J 75, 751-752 PubMed.
  • Drevemo S, Hjerten G & Johnston C (1994) Drop hammer tests of Scandinavian harness racetracks. Equine Vet J Suppl 17, 35-38 WileyOnline
  • Clanton C, Kobluk C, Robinson A & Gordon B (1991) Monitoring surface conditions of a Thoroughbred racetrack. JAVMA 198, 613-620 PubMed
  • Walsh J S (1991) Track design for harness racing. Equine Athlete 10, 38-42.

Other sources of information

  • Kobluk C K (1998) Epidemiologic studies of racehorse injuries. In: Current Techniques in Equine Surgery and Lameness. Ed: N A White & J N Moore. W B Saunders, USA. ISBN 0 7216 4601 8. 
  • Evans D L (1994) Training Regimens - An Overview. In: The Athletic Horse - Principles and Practice of Equine Sports Medicine. Ed: R J Rose & D R Hodgson. W B Saunders, USA. ISBN: 0 7216 3759 0.
  • Drevemo & Hjerten (1991) Evaluation of a Shock Absorbing Woodchip Layer on a Harness Racetrack. In: Proc Equine Exerc Physiol. Eds: Persson, Lindholm & Jeffcott. ICEEP. Davis. pp 107-112. 
  • Leach D H & Moyer W (1990) Racetrack Design and Surface. In: Equine Lameness and Foot Conditions. Proceedings 130, Post Graduate Committee in Veterinary Science, University of Sydney.

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