Conventional wisdom dictates that putting more weight on a horse will eventually slow it down. In fact, this is the essence of handicapping, which attempts to equalise differences in ability between horses by allocating a weight to each according to its ability.
One of the reasons jockeys ride as they do, crouched over the ridge between the shoulder blades of the horse, known as the withers, is to avoid the horse having to accelerate the weight of the jockey during each stride. However, if the weight of the jockey and tack – that is, saddle and stirrups – is less than the weight allotted to the horse in a race, the difference is made up weight pads in a saddle cloth.
This additional weight is so-called “dead weight” – as, indeed, is the weight of the tack – so, according to Newton’s Second Law of Motion, which states that the acceleration of an object is inversely proportional to the mass of the object, putting more weight on a horse must ultimately affects the speed at which it can gallop. In fact, one American study even went as far as quantifying the effects of putting more weight on a horse and concluded that horses running in two consecutive, but identical, races required a weight rise of just 3lb to worsen their performance by one length.
However, despite all the evidence to the contrary, there is still a school of thought that insists that putting more weight on a horse has no effect, whatsoever, on its performance. Proponents of this “weight doesn’t matter” theory argue that weight rises of 6lb or 7lb – which are typical of those imposed by the BHA handicapper – cannot possibly influence the performance of a thoroughbred weighing in excess of 1,000lb.
The waters are muddied still further by the fact that horses carrying more weight tend to fare better, in subsequent races, than those carrying less weight. Over a third of all handicap races in Britain are won by one of the top three in the weights, with the topweight winning most often and so on down the ratings. What this appears to suggest though, is that high-class horses – that is, those at the top of the handicap – are insufficiently penalised in Britain and consequently win more than their fair share of races.