The normal Preliminary cross-country course has approximately 25 jumping efforts. At the same time, your horse will take well over 600 strides at the gallop while completing a two-mile Prelim course. Since you will spend far more time galloping than you will jumping, it follows that you need to study the galloping position. If your position is weak or inefficient, it will have a substantial effect on your horse's performance. Fortunately, there is now scientific research to help you determine the correct galloping position.
In the August 2009 issue of Science, researchers from the Structure and Motion Laboratory at England's Royal Veterinary College, in partnership with the British Racing School at Newmarket, published a study on the effects of human posture on racehorse performance ("Modern Riding Style Improves Horse Racing Times" by Dr. Thilo Pfau, PhD, and others, Science 325, 289). The study proved what horsemen have believed for over a century—that the position modern jockeys use is the most efficient galloping position.
American jockey Willie Simms first used this coiled, crouching position in England in 1895, but it was his fellow American James F. "Tod" Sloan who popularized the new position. Sloan's success rate during this period (in 1898 he won an astounding 46 percent of his races) forced the rest of that era's jockeys to abandon their traditional long stirrups and upright position. This new position led to the greatest incremental change in racehorse times ever recorded: In the decade between 1895 and 1905, average racehorse times improved between 5 and 7 percent. (Since then, times have only improved 1 percent.)
A Revolution in Riding
The 1895-1905 decade must have been an exciting time to be a horseman, considering that Federico Caprilli was inventing the "forward seat" during the same period. Caprilli had as transformative an effect on jumping as Simms and Sloan had on galloping. The obvious connection between the two revolutionary positions is that both place the weight of the rider over the withers in a poised, elastic connection with the horse.
The RVC study analyzed the workload on galloping horses, first using sandbags and riders seated upright on the horses and then using jockeys crouched over the withers in their typical galloping positions. The study concluded that when sandbags or upright riders were in the saddles, the metabolic and mechanical costs to the horses were proportionate to the loads carried on their backs. However, when jockeys crouched over the withers, the metabolic and mechanical loads were reduced. In effect, when riders use a poised position, horses have only to carry the riders' weight, but they are not burdened by having to accelerate the riders' weight during each stride. (As an aside, this study probably answers the long-running argument among horsemen about "live weight versus dead weight." It looks to me as if the live-weight supporters win.)
One important finding of the study is that each time horses take a galloping stride, there is a vertical displacement of their withers as well as the horizontal reach of their legs. This means that if riders stand straight-legged, each stride horses take must push the weight of the riders up, as well as carry the riders' weight forward. In effect, a straight-legged rider is driving his weight straight down into his horse's withers, while a rider who gallops with a bent knee "floats" over his horse.
A coauthor of the study, Alan Wilson, noted that by floating above their horses, jockeys save energy that would otherwise be used to push the weight of the riders up during each stride. Wilson says that efficient jockeys "don't follow the movement of the horse, but stay relatively stationary." Wilson continues, "If he pushes at the right time, it looks as if they (sic) can drive a horse much like a child propels a swing." He goes on to note that because the rider is using his legs as pistons or shock absorbers, "This is hard work." Jockeys' heart rates recorded during races have reached 190 beats per minute.
The RVC study referenced an interesting analogous human study done by Lawrence Rome of the University of Pennsylvania. Rome experimented with backpack design and established that suspending a backpack on bungee cords within a frame caused the weight of the backpack to move less in relation to the carrying human's movement, with a corresponding lessening of the workload.