The Course of the Horse

Dr Martin Brookes

April 2004

If I were a betting man, I would put some serious money on records tumbling at this year's summer Olympics in Athens. The odds, no doubt, would be low. After all, a quick glance at the form book indicates that human athletic performance has shown a steady improvement over the last century or so. In 1896, for example, at the inaugural modern games in Athens, Thomas Burke won the 100 metres gold medal for the USA with a time of 12 seconds. At the Sydney Olympics in 2000, gold medal winner Maurice Green ran the same distance over two seconds faster. At the other end of the athletic scale, Spyridon Louis took just under three hours to win the marathon gold for Greece in the 1896 games. In Sydney, the Ethiopian Gezahng Abera won the same title in just a shade over two hours. But when we switch from two legs to four it's an entirely different story. Why?

While humans continue to get better and better, racehorses seem stuck in the mire. Winning times in all the big thoroughbred races have barely shifted for decades. Today's winners of the Epsom Derby, for example, are running no faster than they were in the 1930s. In the St Ledger, horses are actually taking longer to win the race than they were years ago. And it's a similar story across the water. In 1964, Northern Dancer won the Kentucky Derby in a then world record time of two minutes. The only horse to run a faster race since then is Secretariat, and that was in 1973.

This discrepancy between horses and humans seems all the more remarkable when you consider that horses are specifically bred for racing ability. Winners beget winners, or so the story goes. And yet for all the money and kudos that surrounds the breeding industry, this glaring fact remains: the very best horses are failing to get any faster.

Too few genes

One explanation for this apparent paradox is that thoroughbred racehorses have become so inbred that there is no longer any genetic room for improvement. The paternal origins of every thoroughbred alive today can be traced back to one of only three stallions – the Byerley Turk, the Darley Arabian and the Godolphin Arabian, all foaled in the late 17th and early 18th centuries. With such a meagre genetic foundation, it's little wonder that thoroughbreds should have become so inbred. In fact, the whole thoroughbred standard, still so rigorously endorsed by The Jockey Club, is a quaintly archaic notion, and dates back to an era that was obsessed with 'good breeding', but was entirely ignorant of genetics.

Inbreeding has been a hallmark of the thoroughbred ever since the first General Stud Book was published in 1791, when the pedigree became effectively closed to outsiders. Today, any two thoroughbreds picked at random will, on average, share 13% of their genes with each other. In other words, their average relatedness is about the same as that of half-siblings. Whether inbreeding has had any deleterious effects on the breed is debatable, but thoroughbreds do display a range of health problems that must raise suspicions. More than 80% of yearlings, for example, experience cartilage deterioration in their joints, and more than 95% are afflicted by upper respiratory problems.

But inbred or not, it seems that the genetic potential of the thoroughbred has not been entirely exhausted. For while the best horses are not getting any faster, it turns out that the average speed and performance of thoroughbreds is better today than it has ever been. More horses are running faster, even if the top speed remains unchanged.

Human athletes, so far as we know, have yet to embrace the principles of selective breeding. Improvements in their performance have come from a greater understanding of human physiology, fitness and training. Sports medicine revolutionised athletics in the 1970s and 80s, and its success led many to suggest that horse racing could reap similar rewards from this more scientific approach. In fact, science has proved useful, but not in the ways that were originally envisaged. What it has done is uncover explanations as to why there seems to be a glass ceiling in horse racing performance. We now know that there are good biological reasons why the best horses may have reached the limits of their abilities.

The limits of physiology

The first, and most basic problem for the racing horse is oxygen supply. Oxygen feeds the muscles that produce the energy for running. In humans, producing more energy usually means taking more breaths. But horses are not allowed this luxury when they are running. The horse lacks a collar bone, and when it is running its breathing is linked directly to the movement of its forelimbs. When the front legs hit the ground, the force is transmitted to the rib cage, compressing the lungs and forcing air out. The ribs fall back when the load is lifted from the forelimbs, allowing the lungs to expand and air to be drawn in. What this means in practice is that horses, like dogs, can only take one breath per stride. This obviously places an upper limit on the amount of oxygen the racing horse can get into its body and, ultimately, on how fast it can run.

A second, and related, constraint for the horse that wants to go faster is that its natural level of fitness is already very high. A horse's peak metabolic rate (the maximum energy potential of its lungs, heart and muscles) is about four times more than you would expect for a mammal of its size, and suggests that horses may already be operating at the limits of what physiology and biochemistry can do. No amount of new training techniques and exercise regimes will alter that fact. Biologically speaking, there may be no more room for improvement.

Science or superstition?

But there's another element to this whole story that has nothing to do with biological constraints, and it revolves around the actions of the racehorse breeders. The breeding industry's obsession with pedigree would make perfect sense if winning was a highly heritable characteristic. But while winners sometimes do beget winners, there are many instances when they don't. Secretariat, for example, did not produce a whole new generation of Secretariats.

Winning a horse race depends on a whole variety of factors. There are those things peculiar to the individual, like speed, jumping ability, stamina, strength, intelligence and psychology. And then there are the more arbitrary factors such as the condition of the ground, the crowd, the competition, the weather, the jockey, the design of the course, and so on. You might think that breeders would want to understand these factors in more scientific detail; to fit together the pieces of the pie that make a great racehorse. After all, wouldn't it make more sense to try and identify these individual components, and then use them as a more rigorous basis for a breeding programme?

But in the breeding industry some level of ignorance seems beneficial to the breeders. Racehorse breeders are not really interested in improvements that will benefit the horse population as a whole. They may not care whether horses are getting any faster, so long as their winners continue to command huge fees at stud.

For all its prestige, the sport of kings remains something of an anachronism, seemingly reluctant to join the biotechnology revolution. Antiquated beliefs abound and many practices seem to make no sense. The offspring of winners, for example, are usually sold as yearlings, before any racing potential has been realised. Stallions are still seen as the supreme sex, and are far more highly prized than mares, despite the fact that both make a roughly equal genetic contribution to the next generation. In fact it's females who have the edge, genetically speaking. For not only do they contribute half their ordinary genes, they also pass on their entire set of mitochondrial genes. Mitochondria are the powerhouses of cells; the places where energy is ultimately produced. These tiny energy factories contain their own DNA that is inherited exclusively from the mother. If some aspect of performance is ever linked to this small suite of genes then we might see breeders starting to place more emphasis on their mares.

For all its folklore and its foibles, the popularity of horse racing remains undiminished. This weekend, thousands will gather at Aintree for the premier National Hunt event of the season. The Grand National is the one race when the whole nation tries to pick a winner. Is it a science or is it an art? It's neither and it's both. But whichever horse is first past the post, one thing seems guaranteed – nobody will be looking at their stopwatch.

You may also be interested in these other Channel 4 features

The Origins of Horse Racing in Britain
Find out how the sport of the kings has become the sport of the people.

Best Value Bets
If you're a betting person, try this feature for a low-down on the best value bets.

History of the Epsom Derby
Luck, tragedy, triumph and two English gents, it's part of the story of Britain's most famous race.

Find out more

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Websites

Channel 4 at the races
Get tips and opinions from a team of racing experts, read the latest racing news, browse horse forms and even place a bet or two.

Athens Olympic 2004
www.athens2004.com/athens2004/
Official website of the 2004 Olympics and Paralympics games.

BBC Horse Racing
http://news.bbc.co.uk/sport1/hi/
other_sports/horse_racing/default.stm
Up-to-date news and information on racetracks and events across the UK.

Equine World UK
www.equine-world.co.uk
Tons of information, articles, forums and much more on this horse lover's site.

Grand National
www.aintree.co.uk
Aintree racecourse is the home of the world's most celebrated, talked about and magical race, the Grand National.

The History of Horse Racing
www.racing.horseriders.co.uk/history.htm
Gives an historical timeline of horse racing, with a fun online quiz and references to the General Stud Book, first published in 1791.

Horse Sites.com
www.horsesites.com/XcDirectory.asp
Gateway site with loads of links. Areas covered are thoroughbred horses, breeding history, handicaps, stallion research and more.

The Jockey Club UK
www.thejockeyclub.co.uk
Regulatory body for horse racing in the UK.

Books

	Horse Breeding by Peter Rossdale (David and Charles, 2003) Explains, in simple language, the biological functions upon which horse reproduction is based. Get this book
	Kings for a Day: Aintree's bravest sons by Reg Green (Mainstream Publishing, 2002) Collection of the trials, tribulations and triumphs that have made up the history of the Aintree Grand National. Get this book
	Modern Nationals: The Aintree spectacular by Stewart Peters (Tempus Publishing, 2002) A year-by-year account looking at the runners, riders and dramas of every Aintree Grand National from 1970 to 2001. Get this book
	The Olympics: A history of the modern game by Alan Guttmann (University of Illinois Press, 2002) Traces the history of the modern Olympics from 1896 to 2000, contrasting the ideal of the game with the often politicised reality. Get this book

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