09/28/2020
As riders, we control the level of fitness of our horses, and therefore we must also recognise that in this sense we also take on the role of a trainer. As such, it is important to have a basic understanding of how our horses respond to the demands of the exercise regimes we put them through.
Each component of the musculoskeletal system responds to the mechanical stresses created by exercise, by undergoing a remodeling process. This process strengthens the tissues so that they are better adapted to perform the movements we require, and are at a reduced risk of injury. These physiological processes take a long time over a period of repeated exposure to stress - which is what we are aiming to achieve with training/exercising our horses.
As such, we must understand the responsibility of conditioning their musculoskeletal system with care and empathy. As if we push our horses too much, or overtrain them, not only do we risk overexerting tissues and causing injury, but we risk causing training soreness.
Training soreness typically arises in the muscles, and is as a result of temporary changes within the muscles in response to unaccustomed exercise. There are two types of muscle soreness;
🔹 Acute Muscle Soreness or AMS, which is pain felt in muscles during exercise and after up to 24 hours after exercise, and;
🔹 Delayed Onset Muscle Soreness or DOMS, which typically appears 24 hours after exercise and peaks at 24-72 hours after.
AMS appears during exercise, within minutes of the muscles contracting. This soreness typically disappears between 2-3 minutes up to several hours after the muscle relaxes. It is thought that this soreness can stem from strain on the sarcomeres, the functional units within muscle tissue which create muscle contraction. This strain initiates an inflammatory response within the muscle, which stimulates nociceptors (pain receptors) in the muscle's connective tissue and creates acute pain.
DOMS typically appears 24 hours after exercise, and results in soreness persisting in muscles long after exercise has ended. This soreness is often perceived as a dull, aching pain in the affected muscle, often combined with tenderness and stiffness. Many of us have likely felt this dull ache before in our own muscles after a period of intense activity, often a number of days after the event itself.
DOMS is a protective process, which naturally occurs in muscles as a result of the physiological response to exercise. However, certain exercises, such as movements requiring largely eccentric muscle contraction, are thought to place the muscles at a great risk of DOMS.
Eccentric muscle contraction, is a form of contraction which requires the lengthening contraction of muscles usually to stabilise movements. See in the figure below how the lateral muscles of the foreleg contract eccentrically to stabilise to movement of the forelimb crossing in front of the body, in the half-pass movement.
This form of exercise can cause mild muscle strain, as the tissues are stretched to and possibly beyond their maximum contractile lengthen. This creates microscopic scale damage (microtrauma) to the muscle fibres. It is thought that this microtrauma, coupled with the inflammation that accompanies these tears, stimulates nociceptors (pain receptors) within the muscles connective tissue to create a sensation of pain, and therefore DOMS.
It is here that we must realise as a rider, that by training our horses, we are inadvertently subjecting them to a degree of soreness. As such, we must act in a conscientious manner to determine the most empathetic approach to training which weighs the benefits of a particular exercise, with the subsequent strains and soreness we place on the musculoskeletal system.
Horse’s cannot vocalise that they are sore. Instead they may present with stiffness, or may be lethargic in the days following a high intensity work session. They may be less willing to work or just have an “off day”. It is easy at this point to become frustrated, as they understood and performed an exercise the day before, but had seemingly forgotten how or refused to perform it the next day. It is at this moment that we should take a step back, and consider whether our horses are sore, so that we can rethink our training plans for the day and avoid further soreness or injury.
However, as much as we may want to avoid ever creating discomfort in our horses, we must recognise the fact that in order for them to perform the exercises and movements which we require for their discipline or daily activities, their musculoskeletal system must be adequately conditioned to do so. Otherwise, we risk catastrophic injury by pushing the tissues beyond their physiological limits.
This comes through a regime of targeted exercises appropriate to our horses fitness level, level of training and age, among many other factors. As the body is physiologically designed to respond to external stresses (from exercise and training), and in response will readily adapt to prevent further damage from being repeated from the same exercise.
To achieve this, without causing undue soreness, we must appreciate that it takes 14 days for a horse's musculoskeletal system to become adapted to a training load. Therefore, we should allow this time period before increasing the intensity, frequency or duration of our training regime. In fact, the best way to minimise or avoid DOMS is to start any exercise programme, or introduce any new exercises to a current programme, gradually and gently. This allows time for the musculoskeletal system to adapt to the demands of the new or more challenging exercises.
Thus we are left with the responsibility of maintaining a fine balance between applying enough training load to our horses exercise regimes to adequately condition their musculoskeletal systems, and knowing when to back off in consideration of the soreness which comes with this conditioning process 🏇
