Workload and how to reduce your horse’s risk of injury.
Acute to Chronic workload is a ratio that can be used to help reduce the risk of injury. The body’s tissues adapt to the specific loads applied to it over time. Injuries are often preceded by a spike in workload. Basically, too much load for the tissues current capacity. To improve your horse’s strength and conditioning you have to keep increasing the load, but the key is gradually.
Acute:Chronic Workload Ratio
Acute = workload that week Chronic = average workload over last 4 weeks.
Workload = time, intensity, reps, distance, speed.
A ratio of 1.0 to 1.25 is associated with a decreased risk of injury. A ratio of less than 0.5 or greater than 1.5 is associated with increased risk of injury. Staying between 1.0 and 1.25 avoids spikes of over or under work. For example if a horse does 3km of exercise in week 1, 4km of exercise in week 2, 4km of exercise in week 3 and 5km of exercise in week 4. The acute workload (in week 4) is 5km and the chronic workload (average over 4weeks) is 4km. Giving an acute to chronic workload ratio of 4:5 or 1.25. Another way of saying this is only increase your workload by about 10% per week.
But how do we estimate the workload our horse is doing. There are some apps and devices that look at heart rate or measure how many km’s you ride. Heart rate and speed (or gait) are closely related so you can estimate my multiplying the number of minutes walking by 1, the minutes trotting by 2 and the minutes cantering by 3. Watch the video from Dr Gillian Tabor (Physiotherapist) for an explanation. https://www.youtube.com/watch?v=nQ-G0p7SOlo&feature=youtu.be&fbclid=IwAR1VjTpVd41kVfzBoSTu_9d0bztXkXKRe2uCezuq7WhzZeD2KVjWQvgrAWA
So canter is more work than trot, which is more work than walk. Straight lines is less work than doing circles, which is less work than doing lateral work. And hill work uses more energy than flat work. Galloping and jumping of course use even more energy again. (FYI galloping at 480m/min is a similar intensity to showjumping a 1.1m course at 384m/min). In-hand lateral work at a walk is more tiring than many people give it credit for, as for introducing counter canter or canter half pass, your horse needs to be really quite fit.
Some people say at the start of a get fit program you should walk for 1 month. Walking is great, low impact exercise, with the back going through a large range of movement. Remember walking gets your horse fit for walking. To become conditioned for trotting, cantering or jumping you need to trot, canter and jump. Walking is good for building base endurance after time off.
A few words of caution. * Road work: in-hand or walking is fine, but trotting or cantering on a hard surface is not good for joints due to the concussion.
* Quality and duration: it’s no good if you’ve planned a 1hr walk but your horse fatigues at 30mintues and then spends 30mintues in poor posture.
Bones take longer than heart rate, nerves or muscles to adapt to exercise, and need recovery periods to allow repair. If there are insufficient breaks from high intensity work an imbalance between bone removal and repair occurs, leaving the bone weaker and vulnerable. And no an x-ray can’t give you the all clear. Micro cracks are too small to show on x-ray. By the time something is visible on x-ray it is too late. A rough idea is to do one day high intensity, one day low intensity, one day something different. (Think of a human doing arm day, leg day, yoga day…)
To optimise performance on the day it is usual to train to a higher level and then taper off the workload so the competition feels easier and you have some energy in reserve to cope with the added stresses of competition.
Look at your horse’s current activity level and the activity level you are aiming for. Estimate how many minutes of walk, trot, canter, they would have to do during warm-up and competition for the activity you are aiming for (Prelim dressage test versus 95cm eventing). Then progress the work load between the two staying between 1.0 and 1.25 ratio of acute to chronic workload. It is important to do this at the start of the year whilst you have got the calendar out planning your events so you know how many weeks before the event you need to start training for it.