We all feel stiff now and then, some of us more than others. Many blame their ageing body, long periods of immobility, or strenuous activity for this. Many also blame scar tissue, adhesions or contractures for things that are stiff and painful. However, I think there are a few misconceptions around stiffness and a lot of things can be stiff, but not actually be 'stiff stiff'.
Let me explain what I mean by 'stiff, but not stiff stiff'. Micky Flannagan who is one of my favorite comedians talked about going 'out out' in a sketch of his a few years ago, watch it here it's brilliant. In this sketch he describes how there are different levels of going out, there is 'popping out', 'going out', but then there is 'going out out'. This is the same for stiffness, there are things that are stiff, but then there are things that are stiff stiff.
Now I'm sure you're still thinking 'what the hell is this idiot going on about' so let me explain a little more. When I say something is stiff stiff, I mean it's proper stiff. I mean it's stiff due to 'true' physiological changes, that some structure has altered and changed to cause the stiffness. There are two causes for things getting stiff stiff, they are…
- Joint surface changes
- Soft tissue changes
Joint surface changes are often described as 'wear-n-tear', arthritis, or arthropathy and they can cause a joint to lose movement that may or may not be accompanied with pain. Despite common belief not all joint surface changes are painful. In fact a lot of joint changes are not painful, and the severity of joint surface changes is often poorly correlated to levels of pain or disability reported (ref, ref, ref, ref). However, a loss of movement together with pain and stiffness combined with observed joint surface changes on imaging would be what I class as 'stiff stiff'.
The other cause for things to become 'stiff stiff' are soft tissue changes. All soft tissues are susceptible to adaptive shortening due to many reasons. Muscles can shorten by losing contractile units called sarcomeres. This can occur through ageing processes (ref), disease (ref), lack of activity (ref), or even too much of one type of exercise (ref, ref). Other non contractile soft tissues can also develop shortening due to pathology, injury, or immobility (ref, ref, ref).
Soft tissue changes are the most commonly used explanation by healthcare professionals to explain why patients feel stiff. However, although soft tissue changes can be a cause of true stiffness, most are not. Despite common belief soft tissue changes and shortening doesn't happen easily or quickly and most of the time they do not explain why people feel stiff.
I often hear people blaming sedentary behaviour for causing soft tissue changes and feelings of stiffness. Now there is no doubt that periods of immobility do make us feel stiff, but does it actually cause true structural stiffness. For example long periods of sitting are often blamed for soft tissue stiffness in various areas but mainly the hips, and mainly the Psoas muscle, and yes this is possible, but… and this is pretty big but, there has to be a substantial amount of sitting over a substantial amount of time to cause any permanent changes to soft tissues. And I mean really substantial, like sitting permanently still for 24 hours a day, 7 days a week.
Now most movement, any movement be that a slight shift in position, a wiggle, or fidget will tend to prevent soft tissues from adhering or shortening permanently, and it doesn't have to be done that much or for that long. For example it has been shown that as little as 30 minutes of active movement is all that's needed to reverse the effects of complete immobility for the other 23 1/2 hours a day (ref) and yes I know this is a mouse study, but it does demonstrates how hard it is for soft tissues to permanently shorten, and how small amounts of movement counteract large periods of immobility.
Now that's not to say soft tissue changes and shortening don't occur over longer periods of time, nor is it to say that stretching can prevent contractures for forming (ref). It just highlights that soft tissue changes don't occur as quickly or as easily as most tend to think or claim.
So if soft tissue changes don't occur as quick or as often, what else is causing so many people to feel stiff? Well there is a third cause of stiffness that is not well known or recognised as the other two, this is…
- 3. Protective stiffness
This type of stiffness is what I class as 'stiff' but NOT 'stiff stiff'. Protective stiffness is not due to any structural changes to the joint surface or soft tissues. This kind of stiffness is due to protective guarding mechanisms occurring for various different reasons. Things such as pain, fear, and threat can cause a body part to protect itself and feel stiff (ref). This can occur due a perceived threat of further pain or harm. This can even occur due to protective mechanisms after exercise. For example that stiffness you feel in your legs after a long walk or run or heavy gym session may just be your body trying to 'protect itself' from further perceived 'harmful' activity until it has sufficiently recovered. It can of course also be due to physiological tissue adaptive processes as well (ref).
As I mentioned this kind of 'protective stiffness' is not well recognised or even considered as a potential cause of why things feel stiff for some. It is also not recognised as an explanation as why some 'stiff' things become less stiff really quickly, really easily.
Frozen but not frozen frozen
One of the most common things I see nearly every day in my line of work that is often thought to be 'stiff stiff' is frozen shoulder. True pathological frozen shoulder causes significant soft tissue changes of the joint capsule causing it to shrink and contract (ref). However, often what I see in clinic that is thought to be a frozen shoulder actually isn't a true pathological frozen shoulder. Instead a lot of frozen shoulders I see are actually painful, protected, overly guarded shoulders with no true capsular tissue changes.
I often assess and see patients who appear to have a true frozen shoulder, with a history and clinical exam fitting the diagnosis perfectly having a significant and painful loss of both active and passive shoulder range of movement with a normal looking x-ray. But sometimes these frozen shoulders regain FULL shoulder mobility in only a few days after I've performed a simple intra-articular shoulder joint injection of some local anesthetic and corticosteriod?
So the question you should be asking now is, how is this possible? If it was a true frozen shoulder the joint capsule tissue contracture can't change this quickly with a small volume of local anesthetic and steroid. And you're right it can't, something else was preventing the movement, something else was causing the stiffness, and this something else I suspect is guarding and protection.
This sudden change in shoulder joint stiffness has also been seen in patients under general anaesthetic. This small study here found patients with suspected frozen shoulders actually had FULL range of movement when placed under general anaesthesia. Again if there were true soft tissue changes to the joint capsule the range of movement would still be reduced regardless if the patient was under general anaesthesia or not. Instead it appears these patients had what the authors called 'active stiffness' or what I call protective stiffness.
This protective stiffness is also why I think so many dubious treatments for frozen shoulder appear to work. Silly ridiculous treatments such as hydro-distention, shock-wave, acupuncture, or any of the manual therapy techniques that claim to release soft tissue contractures and suddenly improve or cure a frozen shoulder are first delusional, but also mistaken. There is simply NO way any of these treatments can or do change joint capsule tissue structure. Therefore if any improvements are suddenly made then I suspect that it wasn't a true pathological frozen shoulder in the first place, just like the ones that suddenly improve with my silly injections. I suspect that these are protective stiff shoulders masquerading as frozen shoulders.
So there we go, things can be stiff, but not stiff stiff. In fact I think a lot of what we see in our patients isn't stiff stiff. I think protective stiffness occurs in a lot of areas in a lot of people. For example how much stiffness actually occurs in painful backs, hips, knees, etc and how much is actually protective stiffness due to a patient's pain, fear, and threat of causing themselves further harm or damage. How many of our patients are stiff but not stiff stiff?
As always thanks for reading