Melbourne Cup 2013 winner Fiorente with trainer Gai Waterhouse and strapper Des Fisher at Flemington. THOROUGHBRED racehorses have unique anatomy and physiology that suits them well for racing at high speeds. There are very few 3200m thoroughbred races in Australia, and the horses making it to the final 24 in the Melbourne Cup are truly elite.
They have superior oxygen transport and an ideal mix of muscle fibre types, and are able to efficiently gallop at high speed. But winning the race also depends on how the horse behaves on the day, the jockey, and good luck.
Horses in the Cup will have big hearts with exceptionally high capacity for pumping blood to muscles. During the race, each horse’s heart rate will hit 220-230 beats per minute, with each beat pumping around 1.3-1.4 litres of blood. About 300litres of blood will be pumped to each horse’s muscles and tissues during each minute.
That blood also has an extraordinarily high concentration of haemoglobin – its oxygen-carrying component – much higher than that of elite human athletes.
These factors combine to enable an elite racehorse to consume 250litres of oxygen during the race.
Horses will consume oxygen at maximum rates of 180ml per minute for each kilogram of body weight after the first minute of the race.
Better race results could be expected in horses with the highest oxygen-consumption – but a win depends on more than just higher aerobic capacity. At some stage in the race every horse will do a short sprint, and must also possess the anatomy and physiology needed.
These horses will have the right combination and number of types of muscle cells to provide the ideal mix of endurance and acceleration.
The best have higher proportions of fast twitch oxidative muscle fibres, well suited to fast contractions, oxygen metabolism and fatigue resistance. Slow twitch fibres are better suited to endurance races.
Training for the Cup needs a mix of slow and fast gallops and short distance sprints of 400-600m.
The trainer has the challenge of making the right decisions each morning to promote fitness without overtraining and tiring the horse.
The art of the trainer is still important in preparing the horse to be at peak physical fitness and emotional state on the day.
The horse will have its final sprint or fast gallop workouts three to five days before the race, and be maintained with slow exercise until the race – much like a human athlete tapers before a marathon. This may include treadmill training.
Feed is decreased on the day of the race – having a big mass of food in the intestines isn’t ideal.
A horse’s emotional state is also important. Poor behaviour before or during the race can seriously impact performance. Horses with over-excitability before the race, shown by agitation and excessive sweating, tend to perform less well than their calmer race mates.
Horses that do not relax during the race pull hard against their jockeys, costing energy, so efficiency of galloping is decreased, resulting in poor performance.
The best horses win the genetic lottery, respond to training and racing programs over years and are in the right mental state on the day.
David Evans is adjunct associate professor in equine exercise science at Charles Sturt University. This ran on The Conversation.