7th International Conference on Equine Exercise Physiology

Fontainebleau, France; August 26-31, 2006

The Proceedings are published in book format by Equine Veterinary Journal Ltd. You can buy online at the Equine Veterinary Journal Bookshop. The book is called EVJ Supplement 36 and it is hardback and 671 pages.

New method of measuring core body temperature in exercising horses

Core body temperature is a useful method to investigate how horses undergoing endurance exercise cope with the associated head load, and that of the environment. Researchers measured temperature using a small button-like device that was placed into the uterus of mares, and readings were taken over several weeks, during which time some of the horses took part in endurance competition. This new, non-surgical technique was an effective method of measuring body temperature in exercising horses.

Use of GPS for objective training of Thoroughbred racehorses

Training racehorses relies on both art and science, but in the field scientific methods have been difficult to apply. Global Positioning Systems (GPS) allow set speeds and specific distances to be used in training, and along with workload measurements such as blood lactate levels and heart rate, provide an effective method to train more objectively. More objective training for each individual horse can help to maximise performance, and help to understand the type of training that may increase the risk of injury. Several researchers presented papers on the use of GPS in training horses

Workload of horses during jumping is much increased compared to similar exercise on the flat

Little is known about the difference that jumping obstacles makes to the workload of the horse. In an simple yet elegant trial, researchers showed that even at low level (riding school horses jumping a maximum of 1m), the workload of jumping is much increased compared to that on the flat. This extra workload should be taken into account when training jumping horses.

Heart rate of dressage horses competing at three different levels

There is little information available about the workload of horses competing in dressage, despite its popularity. Researchers measured heart rates of eighteen horses competing at elementary, medium and Prix St Georges dressage competitions at the same venue, and concluded that cardiovascular fitness was probably not a limiting factor in these horses. Specific movements initiated the highest mean heart rates, including10m circle in collected canter (Elementary), collected trot to collected canter transitions (Medium) and extended canter to collected canter transition followed by a flying change (Prix St Georges).

Behavioural abnormalities as a tool to help detect early signs of overtraining

Overtraining is associated with decreased performance and increased risk of injury, but is difficult to predict and to measure. Researchers are working on the development of a prediction tool that includes standardised structural behavioural observations in addition to the normal physiological parameters, with promising results.

Exercising on a negative incline

Despite the fact that performance horses may exercise downhill, no data appears to exist about the cost of running in horses on negative inclines. Researchers investigated the energetic cost and stride characteristics of horses walking and trotting downhill on a treadmill. A negative incline of 5% did not significantly reduce heart rate at walk or trot compared to flat (0% incline) and there were no effects on stride characteristics. The author proposed that the energy cost of braking may have contributed to the heart rates not dropping significantly compared to moving on a flat track.

Electromyographic activity of the longissimus dorsi muscles of the equine back

Horses without back pain walked and trotted on the treadmill and had their back muscles measured using electromyography. Researchers noted that the longissimus dorsi muscles are mainly responsible for the stabilisation of the vertebral column against dynamic forces. The data collected can be used to investigate back pain in horses, by comparing these normal horses and those with back pain.

Recruitment pattern of muscle fibre types during flat and sloped exercise

Performance horses are often trained on uphill slopes, causing them to work harder at lower speeds. Researchers investigated whether or not the muscular work of sloping exercise was relevant to that on the flat, in terms of the recruitment pattern of muscle fibres. The recruitment was identical, showing that it is determined by exercise intensity rather than running speed, and that uphill running results in the same muscle training effect as faster running on a flat surface.

Head and neck position of unridden and ridden horses at walk and trot

Researchers showed that riders always shift the horse’s centre of mass towards the hindlimbs, regardless of head and neck position of the horse. No head and neck position re-established the load distribution to the unridden situation.

High head and neck position in dressage horses: effect on back mobility

A high head and neck position (with nose either slightly in front of behind the vertical) decreased back mobility in international level dressage horses compared to a more natural head and neck position, and increased extension in the thoracic region and flexion in the lumbar region. An overbent position (Rollkur) had the opposite effect on flexion and extension, and increased overall back mobility.

Judging of the extended trot

Researchers demonstrated a lack of objectivity in dressage judging of the extended trot, with differences between the four judges and no link evident between the score awarded and the closer the fore-hind metatarsal angle. In addition, extended trot as the FEI definition was not realised by any of the horses, with all showing a significant difference between the fore-hind metatarsal angles. The authors proposed that it may be anatomically impossible for horses to achieve the gait definition, or that the judging is not consistent.

Short-term exercise training increases insulin sensitivity

Short-term exercise training of horses over seven consecutive days increased insulin sensitivity and caused an up regulation of the transporter molecule that takes glucose into cells, even after 5 days of detraining. The horses were maintained on grass hay to avoid diet-related effects, and a reduction in bodyweight was noted. Training is an effective way of helping to treat horses with insulin insensitivity and of reducing bodyweight, and as a result may reduce the risk of laminitis and obesity.

Effects of dietary energy source and exercise on insulin sensitivity and glucose tolerance in horses

A diet rich in sugar and starch (50% by weight sweetfeed with a starch and water soluble carbohydrate content of 53%) for 6 weeks caused decreased insulin sensitivity and impaired glucose tolerance in mature horses. A 7 week period of exercise training reversed the effect of the high sugar and starch diet on insulin sensitivity. The authors recommended that horses prone to laminitis or obesity not to be fed high sugar and starch diets, and that regular exercise may help protect against the development of insulin resistance.

Effects of low and high daily salt intake

Salt (sodium chloride) is deficient in most horse diets, but is supplemented in many performance horse diets. Endurance horses were given three weeks of no salt supplementation, and then underwent a standard exercise test over 25.9km. Chronic low salt intake was associated with a decrease in plasma volume and an increase in recovery time post-exercise, compared to daily salt supplementation. The supplemented horses regulated their body sodium by increased urinary and faecal excretion. Sodium was not retained during the supplemented period, therefore salt should be supplemented on an ongoing basis.

Effect of dietary glycaemic response after exercise on muscle glycogen replenishment

Adequate muscle glycogen stores are important for optimal performance in sports horses. Horses replenish muscle glycogen after exercise relatively slowly compared to humans, and this could have potential effects on sports that require repeated bouts of exercise on the same or consecutive days. Feeding high glycaemic index (HGI) meals after exercise resulted in a faster rate of muscle glycogen replenishment compared to low glyaemic index meals (LGI) but did not increase the overall glycogen level. The authors warned against the potential health hazards of feeding high soluble carbohydrate meals after exercise to horses not adapted to such meals long term.

Glucose delivery via the GI tract limits early post exercise muscle glycogen resynthesis

Horses resynthesise muscle glycogen post exercise much slower than humans, which reduces their ability to perform exhaustive exercise on consecutive days. Researchers showed that giving glucose intravenously to horses post exercise increased the rate of muscle glycogen storage compared to those given an equivalent oral dose. The oral dose did not increase the rate of glycogen storage above that in the control horses that did not receive glucose post exercise.

Interval exercise alters feed intake as well as leptin and ghrelin concentrations

Horses in training tend to suffer from inappetance, yet the mechanism is not known. Hormones leptin and ghrelin are involved with the maintenance of energy balance in humans and horses, and researchers showed that high intensity exercise was associated with decreases in feed intake and increases in plasma leptin. The authors proposed that leptin may have a role in limited feed in take post training.

Forage-only diets for performance horses – are they effective and safe?

High energy forages tend to be high in crude protein (CP), and researchers investigated the effects of a high protein intake on performance horses (standardbreds). The horses on the high protein diet (16.6%) had increased drinking, urine output, nitrogen excretion, and evaporative losses during exercise compared to those on the control diet (12.5% CP) but were not adversely affected during exercise. All the horses maintained their bodyweight, showing that performance horses can be maintained on forage-only diets. 

Effects of Gastroguard (omeprazole) on markers of performance in gastric ulcer-free Standardbred horses

Gastroguard (omeprazole) is a commonly used pharmaceutical treatment for gastric ulcers. Researchers investigated whether or not this drug affects performance, and found that it does not increase physiological markers of performance in healthy horses. These results are useful for officials to help them make informed decisions about whether or not omeprazole is allowed as approved medication.