We all feel stiff now and then, some of us more often than others. Many blame their ageing body, long periods of immobility, or strenuous activity for this. Many also blame shortening muscles, thickening scar tissue, or increasing adhesions. But I think there are many misconceptions around stiffness and what it is, and what it is not, and I think a lot of things can feel 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 favourite comedians talked about going out but not ‘out out’ in a sketch of his, 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 stiffness and limit movement. 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 surface changes are often poorly correlated with levels of pain or disability reported (ref, ref, ref, ref). However, a loss of movement with or without pain combined with observed joint surface changes seen on imaging would be what I class as one cause of ‘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, but the most common soft tissue to shorten are muscles. Our muscles 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 without doubt 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 don’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 changes in our tissues. For example, long periods of sitting are often blamed for shortening and changing flexibility in various areas but mainly the hip flexors. Now theoretically this makes sense, long periods in shortened positions must cause adaptive changes. But… and this is pretty big but, there has to be a substantial amount of sitting over a substantial amount of time, with little to no movement at all to cause permanent changes to soft tissues. This means to cause hip flexor shortening you would have too sit perfectly still, continuously for 24 hours a day, 7 days a week, probably for a month or three…
The reason for this is that any movement be that a slight shift in position, a bit of fidgeting, or getting up from the chair to walk to another chair will prevent the hip flexor soft tissues from adhering or shortening permanently, and it won’t have to be done that much or for that long. It has been shown that just 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 demonstrates how hard it is for soft tissues to permanently shorten, and how even 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 due to inactivity, nor is it to say that stretching can prevent contractures for forming (ref). But it just highlights that soft tissue changes don’t occur as quickly or as easily as most tend to think or claim.
The other reason
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, and 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. Protective stiffness is due to both central and peripheral neural mechanisms protecting and guarding the system for various different reasons. It maybe due to things such as expectation of pain, or a fear of harm or damage, or even just wanting to take it easy and go slowly after not moving for a while.
All these reasons can and do cause our systems to protect themselves and give us the feeling of stiffness (ref). This can even occur after exercise. That stiffness you feel in your legs after a long 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 and micro trauma processes as well (ref).
Protective stiffness is not as well recognised or even considered as a potential cause of why our patients feel stiff for some. It is also not often recognised as an explanation as to 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 proper ‘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 patients with a history and clinical exam fitting the diagnosis of frozen shoulder 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 suspected frozen shoulders regain FULL shoulder mobility in only a few days or weeks after I’ve performed a simple small volume 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 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 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 delusional, but also mistaken. There is simply NO way any of these treatments can or do change joint capsule tissue structure, therefore any improvements that 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 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