The cross-country course is 6575 to 6800m in length with 43-45 jumping efforts (depending on jump options taken). This means the course takes around 11½ minutes with an average of one jumping effort every 16 seconds. This means they have more jumping efforts in the same time compared with the old-style long format.
Horses will typically take 1300 strides to complete the cross-country course. In canter and gallop horses take one breath in time with each stride and that means they will also move around 17,000 litres of air in and out – that’s equivalent to 57 standard bathtubs of air!
When off the ground over the jumps horses cannot breathe as they require the movement of the abdominal contents and limb contact with the ground to aid both inspiration and expiration and will hold their breath until they land.
Depending on the weather, horses may lose between 5 and 25 litres of sweat on cross-country. For a human athlete, this could lead to a reduction in performance but as horses have a large hindgut they use this as a “spare water store”. However, it’s important that they are allowed to restore water rapidly to reduce the risk of impaction colic.
The terrain at Badminton is almost flat, which means the slight ups and downs of the course only add around 1% extra effort compared with a totally flat course. In contrast, the rolling terrain of Burghley adds around 6% more.
The horses’ muscles on the cross-country produce 4 units of heat energy for every 1 unit of energy that produces movement. Most horses will finish the cross-country with a rectal temperature of 40°C or more. The weather can obviously have a big impact on how much heat they can get rid of on course. Typically the amount of energy produced by a horse on cross-country would boil 12 kettles!
During the XC the main source of energy used by horses is glycogen – the animal equivalent of starch – which is stored within the muscle cells. After XC, depending on how the horse is ridden, its fitness and the weather, horses may have used between 30 and 60% of their muscle glycogen store. Even with good nutrition, only 10-20% of the deficit may be restored overnight before the showjumping. This can lead to poor showjumping.
Maintaining as steady and consistent a pace as possible on the cross-country uses the least energy. Galloping between fences, slowing down for fences and kicking hard coming out of fences is very tiring and may increase the risk of falls in the later part of the course as horses fatigue.
Horses will have a very different perception of cross-country fence structure compared with their riders. Some of the fences this year contain orange and red which horses won’t be able to distinguish from green.
Depending on how excited or relaxed horses are, heart rates in the start box may range from 80 to 130bpm. As they leave the start box towards the first fence the heart rates will quickly increase in all horses to 150-180bpm. By around the time they reach the 5th fence all horses will be working at around 180-200bpm (80-100% of their maximal heart rate; this depends on their breed, genetics and fitness.).
When horses pull up after cross-country they “blow” – deep heavy breathing. This is often wrongly interpreted as the need to “get more oxygen in”. Within a few strides of slowing down the heart rate and breathing will be delivering more oxygen than the muscles need and the blood oxygen levels will return to above normal. The reason horses blow is linked directly to how hot they are. The hotter they are the harder and longer they will blow – unless cooled.
We hope you enjoyed this Scientist’s view of Badminton’s cross country and we wish all the riders the very best of luck!