| VETERINARY |
understand that the forehand works as one apparatus—nothing moves independently from top of scapula to point of shoulder to elbow to knee. If the knee rises and comes forward, the forearm follows plus the humerus (elbow to point of shoulder) and the scapula move through corresponding ranges of motion. Likewise, if the top of the scapula rotates rearward, the point of shoulder rises, the elbow comes forward and the forearm is extended and the knee is lifted and moved forward. Good forelimb movement is characterised by a full range of motion in the swing phase and the stance phase. The latter part of the stance phase is the part of the stride where the horse has rotated his forehand over his front leg and is about to lift that leg from the ground. That is also when the elbow is closest to the ribcage in forward movement. Horses such as #3 have an elbow that could make contact with the ribcage in the latter part of the stance phase ( just before the hoof leaves the ground), but they want to avoid that painful collision (almost bone on bone with little padding). How did our sample horse compensate? He built a muscle over his elbow because he has been using it as a brake. He also built muscle on the underside of his neck. Both of these things were meant to lift the hoof off the ground before the elbow struck the ribcage. Again, this does not lead to efficiency of stride.
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TRAINERMAGAZINE.COM ISSUE 66
| CONFORMATION |
Length of humerus adds reach, and if that humerus has sufficient rise from elbow to point of shoulder, it does not restrict stride rate. Horses with a short humerus that has a steep rise from elbow to point of shoulder tend to have more knee action than is desired on the track. Stride length and turnover rate are the two components of speed. Imagine the difference on the clock between two horses of equal stride rate, but one has a longer stride. It may well be the difference between winning and placing out of the money. In future articles, we will delve into how the variations in length and angle of humerus affect movement plus how tightness of the elbow can impede the rearmost portion of the front stride, thus limiting extension.
Factors for soundness
Aside from the LS and a few factors in hindquarter construction that we will cover in future articles, one of the best advantages for soundness is lightness of the forehand since speed and weight amplify the forces on a horse’s front legs. As a means of measuring lightness of the forehand, I use several markers. The first is the pillar of support, which is simply a line extended up and down through the naturally occurring groove in the horse’s forearm. In general one can see how much horse is out in front of that
line, but specifically, the further in front of the withers the line emerges, the lighter the horse’s forehand. Additionally, a rise in the humerus adds to lightness, as does a base of neck that is well above the point of shoulder. All three sample horses share the above traits for lightness. However, where the bottom of the line depicting the pillar of support emerges also plays a role in soundness and longevity. In Horse #1 the line emerges into the rear quarter of his hoof, ideal placement. In Horse #2 it just catches the rear quarter of the hoof, and in Horse #3 it emerges just behind the hoof. Of the three, Horse #3 is at more risk for damage to the suspensory apparatus (bowed tendons and torn ligaments) and is more likely to hit his fetlock on the racing surface. Please keep in mind that where the bottom of the pillar emerges has little to do with length and angle of the pastern. Shocking, but true. More on this in future articles.
Failure or success
Sometimes it is all in how you analyse the horses and whether you place them where their conformation functions as an asset rather than a detriment. Tiznow proved his championship form at classic distances on dirt. Lady Eli proved her championship form at classic distances on turf. And Horse #3 proved that he was not built to be a successful racehorse.