horse fitness testing

fitness is reported as HEART INDEX.

Fitness is reported as HEART INDEX.

Heart Index is calculated from treadmill heart rate (HR) during trotting and treadmill gallops, and from review of recovery HRs. Blood tests after exercise are also considered.

Heart Index normal range is 75-130, depending on aerobic fitness. Average is 100.

Higher Heart Index is associated with superior staying ability. The very best performances in races over 1600-3200 m have Heart Index values over 120.

Horses with inferior Heart Index (less than 95) will fatigue more quickly in the final 400 m of all races, and poor performances will be expected in most races. If the horse has a far superior 600-800 m sprint, it might win races of 1000-1200metres, but performances in longer distance races will be limited by inferior stamina and inferior resistance to fatigue.

Improved stamina due to higher Heart Index occurs after appropriate training in most horses. Treadmill gallops achieve the desired response if the horse is responsive to training.

Excitement during trot and slow gallop can complicate the measurement in some horses.

Heart Index is associated with aerobic fitness, but it can also be influenced by other factors, including:

·         Horse behaviour and temperament (for example, anxiety, will cause false low values.

·         Lameness, muscle or foot soreness, poor gait action, and respiratory conditions can all cause Heart Index to be decreased, and veterinary diagnosis and attention to these problems can result in improvement.

·         Heart index measured during treadmill exercise in days after a race can be elevated due to respiratory or other problems which can develop during a race. Monitoring of heart index during the recovery period helps guide the management of recommencement of training and racing.

fitness tests with heart rate meters and gps systems.

The principle of fitness testing necessitates accurate measurement of velocity of the horse. Until recently this achievement has only been possible during treadmill exercise tests. New measurements based on studies of the heart rate relationship with velocity haverecently been used successfully in field studies. Recordings are made over 5-6 gallops at least, collecting data from trotting and gallops at 600-750 m/min (16-20s/200 m) and during short sprints. The heart rate at precise submaximal gallop speeds (30-45 kph) can also be assessed. Velocity is measured with an accurate and sensitive global positioning system device carried on the horse or jockey. This technique has been used to describe changes in fitness with high speed training in two year old thoroughbreds, (7) and has been significantly correlated with racing performance in Australian (8) and Japanese studies.


7. Vermeulen A.D. and Evans D.L (2006) Measurements of fitness in thoroughbred racehorses using field studies of heart rate and velocity with a global positioning system. Proc. 7th Int. Conf. Equine Exercise Physiology, eds. Essén-Gustavsson, B., Barrey, E., Lekeux, P.M., Marlin, D.J.., Equine Vet. J. Suppl. 36; 113-117

8. H.L. Gramkow and D.L. Evans (2006) Correlation of race earnings with velocity at maximal heart rate during a field exercise test in Thoroughbred racehorses. Proc. 7th Int. Conf. Equine Exercise Physiology, eds. Essén-Gustavsson, B., Barrey, E., Lekeux, P.M., Marlin, D.J.., Equine Vet. J. Suppl. 36; 118-122


Recent research b y the author has confirmed that assessment of the HR response during submaximal gallop exercise (15-40 kph) and during sprints should be measured for a complete assessment of fitness in thoroughbred racehorses. Occasionally horses with fitness scores (heart index)  do not perform well, and such poor performance could be explained by poor cardiac performance during sustained high speed gallops at high HRs. For example, they could have murmurs of electrocardiographic problems could limit the cardiac output at very high HRs. Complete clinical examinations including evaluation of the EKG during exercise and cardiac ultrasound immediately after exercise can confirm such cardiac limits to performance.

In endurance horses the relationship between speed and HR can be used to guide training intensities, and evaluate future performance potential. Superior performance could be expected in horses with lower HRs during field exercise. Such lower HRs could reflect higher blood and cardiac stroke volumes, and superior economy of locomotion. 

Polar Equine HR+GPS systems are now recommended for use in ridden and driven horses.

Speed is recorded from changes in position every 2-3 seconds, and a heart rate is provided at each of the speed data points. Maps (stylised, or with Google Earth) show the position of the horse at each HR and speed recording, and show the course taken during the workout. Speed is given to the nearest 1 kph, and HR to the nearest 1 beat per minute. Records can be studied over time periods, or over distance. Peak speed during fast gallops is easily recorded. In thoroughbreds.

Regular analysis of these files can help owners/trainers address important questions.
· Is my horse fitter than it was 2 weeks ago?

· Have the heart rates worsened since the last recording, indicating that the horse might have an illness, or be overtraining, or not be properly recovered from its last race?

· Is the horse training in a "zone" that is just right for the individual horse, taking into account the individuals' current fitness and maximal heart rate?

· Am I training a horse that has a profile (heart index) indicating that it has a limited rate of maximal aerobic energy output, so limiting its racetrack performance?

The individual horse’s combination of high speed stamina and sprint speed can be used to guide the type of training used, racing distances selected, and race tactics.

However, evaluation of HRs during racetrack exercise is not without potential problems in evaluation.

· Results in all horses will be invalid in horses that “pull” during the gallop, or do not get an adequate trotting/slow gallop warm up.

· Values will also be influenced by track conditions. Very soft and very hard conditions could decrease the measurements (meaning higher HRs during gallops).

· Fitness values will increase in horses that lose surplus fat, even in the absence of a true change in their cardiovascular fitness. This is in the horse’s interest for best performance

· Racing ability will be influenced by a horse’s acceleration, and 400-600 metre sprint speed, and other factors not measured by HR assessments.