Perhaps the most interesting questions for some endurance riders are about conditioning. How fit is my horse? What is too little or too much work? How do you tell?

It is a huge subject, affecting all disciplines, and has amused equine physiologists for decades. So please forgive my simplifications and omissions; there is enough material to fill many books. The goal here is to provide a few solid tools and a few guidelines for making decisions.

How do I really know how fit my horse is and if my conditioning program is working?

There are several fitness tests you can try. Two require a heart rate monitor: the Constant Speed Test and Constant Heart Rate Test. The Recovery Heart Rate Test is done with a stopwatch and stethoscope.

Constant Speed Test requires a trail you can ride approximately every three weeks. Many people suggest between six and 10 miles depending on the terrain. The first step is to ride the trail at a speed that is not maximal, but is comfortable for your horse, something you can do all day without worry.

Record your pulse monitor readings every 10 minutes. You can always ride this same trail a couple of days later doing the same thing to be sure your readings are correct.

Work your horse as you would normally and ride this trail again in three weeks in the same elapsed time as you did originally. It is important for the retest day's ambient temperature and humidity to be as close as possible to the original day.

If you choose to graph the results, the pulses should be lower.

Constant Heart Rate Test is similar to the above test in that you will be looking at pulses, but this time you will keep the pulse the same. You adjust the horse's speed to maintain a steady heart rate. If you don't have an idea of what pulse to start with, try choosing a speed that is comfortable for the horse, say an easy canter/lope for a few minutes at that steady speed. This will be your target to maintain. Try to get this target when the horse is well warmed up and relaxed.

For example, let's say that a particular horse at a particular state of fitness has a canter/lope pulse of 130 to 135 bpm; that is the target for this horse.

The test starts with a warm-up. Let's say you ride half an hour to a particular place. From that spot ride approximately 15 minutes to another recognizable place, maintaining a pulse that is in your target range, in the case of the sample horse 130 to 135 bpm.

In three weeks retest using the same trail, same period of time warming up and hopefully the same weather. If your conditioning program is working properly you should be able to go farther on the retest.

Recovery Heart Rate Test will be familiar to endurance competitors. Like the Constant Speed Test, you will use a predetermined trail and ride it at a challenging but submaximal level. This time you will take a pulse before you start. At the end you take a pulse immediately (if you have a heart rate monitor) as well as two, five, 10, 15, and 20 minutes with a stethoscope. Graph this and compare with results in three weeks.

Am I conditioning enough?

Any of the three tests above will give you information about whether your conditioning program works the way you want it to, but there is one more tool to help answer this question. It is essential to keep records. They don't have to be fancy, but they have to be honest. Every time you ride, at least mark down the distance and time.

Overtraining syndrome

What is too much?

We have heard rest is as important as work, but what actually happens to horse and human physiology with overtraining is complex and not fully understood. The symptoms are observable, however.

We have been using the pulse as the monitor for fitness tests. We can also pay attention to it as one sign of overtraining. If your conditioning program has been working and your horse has been on a line of consistent improvement and suddenly you start getting odd, higher-than-expected readings, this may be a sign of overtraining.

Other symptoms noted in humans, as well as horses, are decreased appetite and weight loss, irritability, and a sudden drop in performance. In humans, because they can talk, there are reports of insomnia, pain in muscles and joints, headaches, lack of energy, decreased immunity, depression and a higher incidence of injury.

On a measurable level, studies on horses show weight loss and lowered glutamine levels, which has an effect on the immune system. Recent research tracks a considerable drop in growth hormone as a symptom of overtraining. In human studies overtraining is linked to illnesses.

If your horse's performance nosedives, overtraining syndrome is something to consider. The cure is rest, but it's better to avoid overtraining in the first place. Current thinking on prevention suggests variations in workload, cross-training and rest days. Careful behavioral monitoring is wise, especially after hard work.

Record keeping is, in some ways, the key. It is much more difficult to kid ourselves when we see the pattern over the weeks and months.

• Monitoring training in athletes with reference to overtraining syndrome. Foster, C. Medicine & Science in Sports & Exercise: July 1998 - Volume 30 - Issue 7 - pp 1164-1168, Applied Sciences: Symposium: Training/Overtraining: The First Ulm Symposium.
• Plasma amino acid concentrations in the overtraining syndrome: possible effects on the immune system. Parry-Billings, M; Budgett, R.; Koutedakis, Y; Blomstrand, E; Brooks, S.; Williams, C.; Calder, P. C.; Pilling, S.; Baigrie, R.; Newsholme, E. A.; (C)1992, The American College of Sports Medicine.
• Changes in maximum oxygen uptake during prolonged training, overtraining, and detraining in horses. C. M. Tyler, L. C. Golland, D. L. Evans, D. R. Hodgson, and R. J. Rose. Department of Animal Health, Department of Animal Science, University of Sydney, Australia.
• Overtrained horses alter their resting pulsatile growth hormone secretion. E. de Graaf-Roelfsema, P. P. Veldhuis, H. A. Keizer, M. M. E. van Ginneken, K. G. van Dam, M. L. Johnson, A. Barneveld, P. P. C. A. Menheere, E. van Breda, I. D. Wijnberg, and J. H. van der Kolk, Faculty of Veterinary Medicine, Medicine Section, Department of Equine Sciences, Utrecht University, Utrecht; Department of Clinical Chemistry and Faculty of Health Sciences, Department of Movement Sciences, University of Maastricht, Maastricht, The Netherlands; Department of Pharmacology, University of Virginia Health Sciences Center, Charlottesville, Virginia; and Department of Human Physiology and Sportsmedicine, Free University of Brussels, Brussel, Belgium.
• Adaptation and overtraining in horses subjected to increasing training loads. G. Bruin, H. Kuipers, H. A. Keizer and G. J. Vander Vusse, Department of Physiology, University of Limburg, Maastricht, The Netherlands. Overtraining syndrome in horses. C M McGowan and D J Whitworth, The University of Helsinki, Finland, The University of Queensland, Australia.
• Equine Studies Diploma, University of Guelph. Office of Open Learning, 160 Johnston Hall, Guelph, ON, Canada N1G 2W1, 519 767-5000, www.equinestudiesdiploma.com.