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Does fitness capacity vary according to a horse’s type or breed?

“There have been no robust studies, to my knowledge, that show differences in exercise physiology between breeds,” says Liz Barr. “That said, horses have been bred for different jobs for centuries, so it would make sense that a horse bred for his stamina and ability to pull a plough may not make an ideal eventer.

“Conversely, performance is based on a combination of training, which encompasses cardiovascular fitness, rideability and genetics,” she adds. “Genetics alone will not guarantee success in modern equestrian sport.

“In horses, as in humans, performance is related to maximal oxygen uptake; elite athletes will have a higher maximal oxygen uptake (VO2max) compared with non-athletic individuals. There is evidence in horses, as in humans, that VO2max is associated with heart size. Larger hearts have been shown to be associated with improved performance, not only in thoroughbred racehorses, but also in standardbreds and Arabian endurance horses.”

What’s the most effective approach to fittening?

“Fitness can be defined as capacity for exercise,” says Liz Barr. “The aim is to increase fitness without incurring skeletal injury, by progressively increasing workload.”

Training the muscular, skeletal and cardiovascular systems involves upping the intensity, duration and frequency of work.

“The intensity of work is the rate of energy expenditure during an exercise period,” she says. “While this is primarily related to speed, intensity can also be increased by working a horse uphill, into a headwind or through deeper going. Duration relates to the time spent exercising in any one session, while frequency is how many times that work is carried out over a particular time.

“There is no magic formula for all horses. Fitness training should be a gradual process, and tailored to an individual horse and a specific sport.”

How does heart rate relate to fitness?

“A fit horse should be able to work at a particular speed with a lower heart rate than before he was trained — and he will also have a quicker recovery after exercise,” says Liz Brown, explaining that heart rate is influenced by breed, age and genetic athletic ability, ranging from around 60-80bpm (beats per minute) at walk to 180-220bpm at gallop.

“While a fit horse cannot be distinguished from an unfit one purely on the basis of heart rate, it is possible to use responses over time to measure the change in fitness of an individual horse during a training programme.”

Liz suggests using a heart-rate monitor during exercise, ensuring that the electrodes have good contact with the horse’s skin for accurate feedback.

“You can monitor time spent at particular heart rates while hacking, schooling or jumping, for example, or set a fixed exercise test — such as a particular gallop where the heart rate can be sequentially monitored as the horse gets fitter,” she says.

Why is rest important?

“Incremental increases in training and rest periods between sessions allow muscles to adapt and recover,” says Liz Brown.

“Muscles respond to training in various ways; capillaries increase in number, oxygen uptake and aerobic capacity improve, muscle fibres and enzymes undergo changes, and glycogen storage capacity increases. Performance is further enhanced by the delayed onset of lactate production and fatigue in muscle cells.”

Relentless work may be counter-productive, however, as Liz explains.

“Injuries are more likely to occur when body systems are working to the point of fatigue,” she says. “Structures such as tendons and ligaments are at particular risk as they are subject to increased loading as muscles tire.

“It’s easy to forget how hard a horse is working when you’re concentrating on perfecting a movement, so make a point of including sufficient rest periods within each session. When training muscles for improved motor skill, short episodes closer together are more effective than one longer weekly session.”

Liz explains that an effective work-rest pattern may involve a day off once a week or after a three-day cycle of varied work, or following a competition or hard workout.

“Rest days can include light work, time on the horsewalker or turnout,” she says. “A short ride around the roads could be considered a rest day, but hacking can be an excellent part of a fittening programme if there is access to hills and varied terrain.

“Hacking and turnout can help with a horse’s mental attitude, maintain his suppleness and reduce the risk of him ‘tying up’ — a condition called exertional rhabdomyolysis, sometimes triggered by time off without an appropriate reduction in hard feed.”

When work stops, must fitness levels drop?

“Horses appear to have an ability to maintain cardiovascular fitness, even with quite lengthy periods of enforced rest,” says Liz Barr.

“In a recent study, horses were trained for 18 weeks before working at a reduced intensity for 12 weeks. A relatively low exercise level, such as cantering three minutes a day for five days a week, at 70% of maximal rate of oxygen consumption, was shown to be sufficient to maintain certain performance values.

“The same researchers had also previously shown that markers of cardiovascular fitness were maintained in a group of young, trained horses left free at pasture for eight hours a day during 10 weeks of rest.”

Ref Horse & Hound; 19 April 2018