Why do we get injured?

This cannot be answered simply, but here I will discuss the current theories. The beauty of evidence based practice is we never fully know the answer, but consistently move toward the truth. Buckle up, it’s a bumpy ride, and the theory is more empowering than you would think.

There are a number of factors that are thought to contribute to injury, and the most important caveat is that all humans are different, therefore we cannot pin pain or an injury down to one factor. Examples of oversimplification include: your knees must have gone over your toes, it was your shoes, tight muscles, overpronation, and my favourite, posture. The list goes on and on. Unfortunately, (or fortunately) these theories do not stand up to the rigours of research, however imperfect research may be. As easy as it may be to tell every single person they have knee pain from running because of the brand of shoes they are running in, this is misleading. I have met top 5 Comrades marathon runners who run in the lower-end brands and this doesn’t seem to hamper their performance.

there is a consensus in the rehab COMMUNITY that we should REPHRASE ‘repetitive stress injuries’ into ‘training load errors’.

Currently the most accepted theory for why we develop ‘repetitive strain injuries’ is to do with load capacity. Acute injuries, for example, a hamstring tear, can be viewed in a similar light. These theories are fantastic as they make a lot of sense , and boy oh boy have we strayed in rehabilitation from these simple concepts. Dye’s Envelope of Function (go and look it up if you’re curious) has been around since the 60s and only in the last 5 - 7 years have we started seeing its value. I will break down what we mean by Load and Capacity and show how the theory can be applied.

WHAT IS LOAD?

Firstly when explaining LOAD in this context, it is the strain we impose on our body in the form of exercise, in the hope that it will adapt. An example of load could be a 5 kilometre run. It can be the 40 kg Leg Press done in the gym to help the quad muscles grow in size. If it wasn’t for the wonderful ability of the body to adapt to stress, no individual would be able to go from being a beginner runner to completing the Comrades Marathon.

In good quality training, we are trying to make our bodies harder to break, so that we can withstand the rigours of the sport we choose to do. Never mind rigours of sport, the rigours of daily life. Training load causes a series of responses in the body that lead to adaptive changes.

This example of load could be a leg press exercise at the gym.

The beneficial adaptations to exercise. Once capacity increases, the load needs to be progressed to see further adaptations. This cycle is how good quality training can lead to desired adaptations.

WHAT IS CAPACITY?

Now that we have discussed load, where does the capacity come into play? A fantastic example of capacity is the shin bone of a mauy thai martial artist. Professional mauy thai fighters are able to withstand direct kicks to the shin with a huge amount of force. This is due to the fact that over time, their shin bones have thickened and hardened in response to the load imposed on them (repetitive kicks in training). If an amateur fighter had to be kicked in the shin by a professional fighter, the bone would not be able to withstand the load applied quickly and would break.

As much as tissues can adapt positively to load, they also adapt to prolonged rest or inactivity by a REDUCTION in capacity. Resting a minor injury for too long can result in significant reductions in that tissue’s capacity. If too much load is applied again too quickly, overload may occur.

Prolonged periods of rest or a sedentary lifestyle can result in reductions in capacity. Introduce or re-introduce load too quickly, the structures may not have sufficient time to adapt and may be overloaded.

Now the confusing part comes in when we start to look at the other reasons why capacity may be reduced. Factors that can that impact capacity are sleep, diet, stress, mental health and your genetic makeup. Some runners can increase their volume extremely quickly whilst others do everything ‘right’ and still struggle. This can partly be attributed to individual genetics. You know that friend that flies past you in a triathlon with very little preparation? Yeah, they won the genetic endurance lottery. Throw in socio-economic factors, support systems, self-efficacy, to name a few, and things can get muddled.

Other factors that affect capacity. These are also highly individual.

What is overload?

A perfect example of overload was observed in my practice after the initial COVID-19 hard lockdown, and can be viewed from two sides. One, fit athletes that had to rest for a prolonged period of time and two, individuals that had a new appreciation for exercise after being cooped inside for so long. The trained people had periods of rest they were not accustomed to (which resulted in reductions of capacity) and then post lockdown, picked up the same volume they were doing pre-lockdown. Their bodies didn’t have time to adjust quickly enough and I saw a number of minor injuries. On the other hand, new runners were enthusiastically getting into their new sport and were increasing their distances too quickly. Their bodies were also not prepared for the quick increase in volume and started protesting. Thankfully their very clever nervous systems stopped them before it became too big of a problem.

Another favourite analogy of mine is the sports day at your child’s school. Previously very fit parents that have given it one too many years of rest giving the 100 metre sprint a go at maximal effort. Enter, hamstring strain. I am not saying don’t play with your kids, but take caution if it has been a while!

Too much too soon, after too little for too long.

So what happens when we are actually injured? Correct rehab allows for brief resting of the tissue structures followed by a graded program of load increases to help restore the capacity of the affected tissues. As the great Greg Lehman says, and I will tone it down for the more sensitive reader, “Calm stuff down, build stuff back up.”