An x-ray or scan is just part of the picture, it doesn't necessarily tell you how to get better or what you can and can't do. 


Last week I posted a chart on our Facebook page that took 2 studies looking at scan findings and their correlation to pain. I highlighted specifically the degenerative or arthritic type changes that were seen in people without pain. I wanted to share more information on this and felt that this would better come from a blog as there is a lot to explain! I think it's also important to say that in some instances, imaging is extremely important - but it doesn't tell the whole story.


Firstly, our body is an incredible thing. It is constantly remodelling itself to produce new tissue and keep everything working well. In addition to this, it adapts to the environment that we place it in. What I mean by this is that if we tell it to, it will get stronger, faster, more flexible etc – quite simply this is the result of a progressive training plan. I always use the analogy of building a big bicep; if you want to do this, you go to the gym and lift progressively heavier weights so that you muscle changes to get better at lifting the weight (it gets bigger).


However, the opposite is true too, if you do less with your body it will adapt; it will get weaker, slower and less flexible. This has been since in many studies, mainly on military recruits and observations of astronauts.

If, however, we continue to do what we have always done, then generally, our body will continue to maintain the same levels. It does this my constant chemical reactions and we call this homeostasis ie staying the same.

And this is really important to acknowledge – if we want our body to progress, we need to tell it to progress. It’s often the reason why rest alone does not always resolve the problem to the point you can return to the previous function.

So, let's go back to the scans and the issue with seeing things on scans but not being in pain. Well, there’s a really interesting paper from Scott Dye in 2005 that I would like to tell you about. If you want to, you can access the full paper here.

Dye tells us that he has arthritic changes on the back of his knee cap. As a trial, he had a local anaesthetic to numb the skin and then put a camera and probe inside the knee. He found that the back of the knee cap (where the arthritis is) actually wasn’t painful to poke. He did, however, find that the capsule and the fat pad were very painful. He also found that when he increased the pressure in the back of his knee cap with a saline solution he got increased pain in the front of his knee. Decreasing that pressure resolved it. This suggests that the wear and tear is not the cause of the pain but would be more to do with increasing pressure in the bone. His suggestion was that a loss of tissue homeostasis could replicate this.

This seems to add weight to the view that it’s not always the structural change that is the problem itself and led Dye to suggest the model of the ‘envelope of function’. Below you can see the graphs from his paper to illustrate this idea. The large area termed ‘zone of homeostasis’ is the level of load placed on a tissue that would keep the tissue the same. The ‘zone of sub-physiological underload’ is the area at which tissues would decrease homeostasis – ie a prolonged period of bed rest will cause decrease muscle size and bone density. The zone of ‘supraphysiological overload’ is just outside the zone of homeostasis and represents a level of load that would maybe irritate the tissue but cause no structural damage. The zone of ‘structural failure’ however represents a load that would cause the failure of the tissue involved such as a stress fracture. In the second chart, you can see some activities placed to represent estimates of load vs frequency.




Put simply our tissues have a tolerance. If you work past that tolerance for a while you may get pain. However, if you work a long way out of that tolerance you may get structural failure.


Taking this back to the whole ‘wear and tear’ discussion, there may be changes in your joints, but that probably doesn’t matter, as long as you work within your ‘envelope of function’ or tolerance – let’s call it tolerance from now on!!


Now I hear what you’re saying – ‘So what? You’re telling me the same as everyone else – if it hurts then don’t do it.’ But probably the reason you are reading this is that you are hoping for something different, something new and something that will allow you to do that thing that you have been told not to do – in my experience, this is normally running.


Well, I’m not going to stop there. I’m not suggesting you should never run – I want you to run. The big message here is this – YOU CAN MOVE YOUR TOLERANCE.


When you irritate a tissue here’s what happens to the graph:


Tolerance decreases: The activities that were within your tolerance before, no longer are and you get pain as a result. The aim would be to move the tolerance level in the opposite direction if it can decrease we should be able to increase it. We do this by graded exposure to pain-free (pain-free may be debatable but is what I find effective) loads with rehab exercise.


It’s that simple! If you have pain in your knee (for example) when you run then we probably need to make things a little easier for you, and then gradually build it up again by gradually increasing the load through the knee until the activities you want to do are in your tolerance levels.


Now there are 2 things that are key here:


1.      You need to progressively increase the load (we’ve said this already quite blatantly)


2.      Before we can increase load we need to decrease it to levels inside your tolerance.


I believe that these 2 things are just as important as each other – don’t expect to get better if you just rest, and don’t expect to get better if you keep working outside your tolerance.


This is why rehabilitation is key to long term resolution. Once the tissue has reduced tolerance, the only way to improve its tolerance is through a progressive rehabilitation plan – this takes time and is hard work, but it does the job.


Considering this tolerance model is also important for injury reduction too. Running is a great example of this. If I always do the same 5-mile running loop 3 times a week as my exercises, don’t be surprised if you get pain after a while. Why? Well, our tolerance can be affected by lots of different things; sleep, stress, nutrition etc and the load could be affected by having a particularly busy day which means the accumulative load is larger. I’ll explain in a chart:

This is a very basic chart to illustrate the point. If all you do is your normal daily activities and you’re always doing the same thing, your bodies tolerance will stay at the same level – every day the tolerance will remain the same (assuming you have good nutrition, sleep, stress etc). However, the problem comes when you have the below chart.

Here, is a chart for the same person as above, but say that they have had a tough day – work has been more demanding, or they have significantly increased their running one day. This is where you are at risk. It’s the danger of keeping your tolerance level at the same level as a ‘normal day’. So, in order to reduce injuries you need this:


Where the tolerance of your tissue is much higher than your daily requirement and so you can easily deal with small changes. Again, this is something achieved through training using a progressive plan.


As I have suggested, there are other things that come into play with an injury such as psychology and nutrition. However, the majority of people I see in the clinic who have not improved with previous treatment, it’s because the load has not been progressed enough.


Sorry for all the graphs and charts, but the point I’m trying to make is that from a musculoskeletal tissue point of view, to reduce injuries you need to increase your tissues tolerance to load. This is done through exercise – mainly a strengthening program. The same is true when you are injured – a progressive loading program is necessary in order to return to function. Pain-relieving treatments can help initially start you off but it’s the rehab plan that finishes the job, gets you back to function and keeps you there.


Finally – going back to the scans – maybe the changes we see on scans put you at risk (a smaller surface area due to less cartilage means increased load at contact points) but it certainly isn’t the change itself that causes pain in all cases. Maybe when you’re in pain you are just working outside the tissue's tolerance and need to improve tolerance slowly. I find this works well, but it takes time, hard work and patience. Rehab works…………. But it’s hard.


Thanks for reading, Josh.