AS the technicality and speed of competition has increased in recent years riders are using studs more and more. Studs are mainly used on grass surfaces, but can also be used on sand and artificial surfaces.

When surfaces have a greater potential for the horse to slip, such as wet grass, this can cause the horse to lose confidence. This loss of confidence may result in reduced performance when jumping or less expressive movement.

Studs are often used to optimise the amount of grip the horse’s foot has upon contact with the surface in favour of enhanced performance. However, by using studs the hoof-surface-interaction is changed, and altering this natural process may lead to an increased risk of injury.

This study sought to determine if any changes occurred in canter and jumping performance when using studs on an artificial sand and fibre surface.

METHOD

Ten competition horses were used during the trial period and all were tested under two different conditions: canter and jumping without studs (control) or canter and jumping with studs. Two studs, of the type commonly used in competition, were placed in the heel of each shoe.

To reduce variation in riding style the same test rider was used for the duration of the test period. The test fence was set as a 1.20m Oxer with a 1m spread.

Slow motion video footage was recorded using two cameras at canter and while jumping. This offered a closer view of the limbs and also a view of the horse as a whole. This allowed for evaluation of jumping performance in analysing parameters such as take-off angle, limb height over the fence and landing distance.

The close-up view of the limb allowed measurement of any effects of studs on the hoof-surface-interaction.

RESULTS

Limb movement

There was a significant increase in take-off angle (4.5°) when studs were worn compared to the take-off angle without studs, as shown in Figure 1. This increase in take-off angle leads to a more upward trajectory over the fence and, as such, may give greater elevation over the fence as this is determined at take-off.

This more upward take-off is a desirable attribute of jumping technique. For example, in Linear Scoring Evaluations, such as those held by Horse Sport Ireland or the KWPN, an upward take-off angle is awarded more marks and as such is sought after in jumping technique.

Elbow angle at suspension was significantly smaller with the use of studs compared to without studs. This was a decrease of 4.41 °s, as shown in Figure 2. This more acute angle gives greater limb retraction during suspension and therefore improved limb clearance over the fence.

Hoof-surface-interaction

The equine hoof and leg are subjected to great forces upon hoof contact with the ground. The hoof and limb of the horse act to dissipate the shock associated with hoof impact. Known as the hoof mechanism, the hoof has three functional areas: the heels for dampening, the wall, frog and sole for support, and the toe for forward propulsion.

The surface interaction may be described as the response of the surface to the loads which are applied to it by the horse and the resulting effects on the horse.

Stance duration

Stance duration is the duration of time the hoof stays in contact with the ground; this was measured from the time of impact until the heel lifted. A shortening of stance duration by 0.01sec per stride with studs was seen on average across all phases, as shown in Figure 3.

This observation may be interpreted in two ways. Firstly, from a performance point of view, this shortened stance duration means that the horse is taking less time to cover the ground. Take for example, a show jumping course of 600m and a horse with an average stride of 3.66m, needing 163 strides to cover the set distance.

Putting the results into context, that means a time saving of approximately 1.6 seconds during the round. This time saving may have huge competitive advantages as many classes at 5* level in show jumping, such as the Global Champions Tour, or World Cup Series are won on times differing in seconds or even less.

Secondly, from an orthopaedic health view point, this alteration in the hoof-surface-interaction, may limit the natural mechanism of shock dissipation.

Slip distance

Slip distance was defined as the distance from the point at which the hoof hit the ground to where it stopped sliding forwards. Slip distance was significantly reduced across all phases. The decrease in slip distance of 4.35mm is shown in Figure 4. A small amount of hoof slip is considered to be beneficial and it is thought to decrease the forces associated with impact.

Studs appeared to be more effective in limiting the hindlimb slip compared to the forelimb slip and in the trailing limbs compared to the leading limbs. The slip distance of the forelimbs was reduced by 12.05mm with studs, and slip distance of the hindlimbs was reduced by 15.74mm with studs.

This was a 30% and 39% decrease in slip distance, respectively. Additionally, slip distance of the leading limbs was reduced by 12.37mm with studs and slip distance of the trailing limbs was reduced by 15.45mm with studs. Again, this was a 28% and 43% decrease in hoof slip distance with studs, respectively.

As shown by this research, the use of studs does alter some of the natural mechanism of the hoof, this may then in turn increase the concussive forces experienced by the hoof and limb. In particular, the reduction of slip distance and shortened stance duration are of concern.

It may be argued that the use of studs may lead to an even greater risk of injury. This is similar to the way knee injuries in soccer players have been linked to a fixed foot, caused by the use of studded sports boots.

CONCLUSIONS

Studs increased grip on a sand and fibre surface while at canter and jumping as shown by a decrease in slip distance at all phases.

Studs had positive effects on jumping kinematics such as an increased take-off trajectory, greater limb protraction at suspension and an increased landing distance (results not shown).

While the use of studs does provide increased grip and performance, the alterations in limb movement and hoof-surface-interaction could create a potential risk for injury and need critical evaluation.

Thomas Dunbar is a graduating student of the University of Limerick’s Equine Science BSc undergraduate programme (2017). Further information on equine-related courses (Certificate, Diploma and Degree) offered by UL can be found online at ul.ie