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. These studies assist with calculation of the velocity at
which the horse attains its maximal heart rate (VHRmax). 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
VHRmax is a
measurement of high speed stamina. It represents the
velocity at which there is no further increase in aerobic ATP resynthesis.
Increases in velocity must therefore depend on increased rate of anaerobic
metabolism, and this metabolic response is quickly followed by fatigue. It has
been estimated that fatigue will ensue after approximately 600-800 metres of
maximal speed gallop that involves high rates of anaerobic energy
output.
Recent research b
y the author has confirmed that assessment of the HR response during ubmaximal
gallop exercise (15-40 kph) should be measured as well as VHRmax for a complete
assessment in thoroughbred racehorses. Occasionally horses with high VHRmax
do not perform well, and such poor performance could be explained by poor
cardiac performance at high HRs (which can exceed 225 in some horse). 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.
An example of simultaneous HR (top line)
and velocity recording in a 3 year old thoroughbred racehorse is presented
below. This horse walked at for 500 m, trotted at 18 kph for 800 m, then
galloped at 38-42 kph over 3000 m. The recording was generated with a Garmin
Forerunner 301 GPS system adapted for use in horses.
Polar Equine HR+GPS systems are now recommended for use for ridden and driven horses, such as trotters and pacers.
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, this value can range from a low of 60 kph to over 70 kph in the
best sprinters.
Regular analysis of these files can help owners/trainers address
important questions.
· 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 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).
