Monday, 19 October 2015

How Our Tissue Responds to Pain.

The Pain System #1.

This is the first of several blogs I’m planning covering the pain system. In this blog I’m going to look at how tissues detect pain, whilst the next blogs will cover how the spinal cord and brain responds to these signals.
Pain is the reason most patients come to see me. There are other reasons: clicking, stiffness, swelling or pre-emptive injury prevention; mostly people who see me come because they are in pain.
The purpose of pain is to act as a warning signal. It occurs when the brain perceives damage or the threat of damage and wants to alert our body to take action.
Where does pain come from?
In most situations the perception of pain in the brain is fuelled by messages from the tissue where the threat is occurring, typically tendon, muscle and skin along with many other less well-known tissues such as fat pad and synovia.
All these pain-reporting tissues contain nerve receptors that alert the brain to what’s happening within the tissue due to stimuli such as stretching, pressure, heat, cold. As the stimulus increases so does the frequency of discharge of the receptors. Above a certain level of stimulus they start to report what we know as pain.

Slow onset injuries:
With slow onset injuries the tissue is put under successive stress. As it starts to get close to the damage threshold it sends early warning signals. A result of these is that we experience pain but no actual tissue damage has yet occurred.
If we then to continue to load and stress the tissue we might go on to cause actual tissue damage and injury. So listening to early warning signals is a key part of managing the everyday load and stress on our body.
If we sit too long our back starts to ache due to prolonged compressive static loading on the tissue. So we get up and move around. If our achilles starts to niggle due to increased mileage we take a few rest days or drop our mileage down to let it settle before increasing at a more conservative rate. Well, in theory at least.
Sudden, acute injuries:
With a sudden onset injury such as a sprained ankle or torn muscle a one-off load smashes through our pain and damage thresholds in one go. Pain and actual damage occur simultaneously
This type of pain tends to be far more intense and generally has a reasonable correlation with tissue damage. It is very effective in making us stop so we don’t cause further damage.
How does the pain threshold vary?
The load a tissue can tolerate before damage occurs gets higher the more load and stress we put through our body – this is why we train.
The achilles in a trained thirty-year old runner will normally have a much higher tolerance to loading than a seventy-year old sedentary person.
In ‘normal’ tissue the pain threshold shadows the damage threshold. As the tissue becomes stronger the nerve endings adapt and increase their threshold-level so it stays just below threshold for actual damage.
Conversely, when we damage tissue it becomes weaker. The load it can then tolerate before further damage occurs is decreased.
In this case the pain threshold is lowered. This occurs through a complex network of chemical and cellular interactions resulting in the production of a group of chemicals that directly lower the tolerance levels of the nerve endings. Below is a diagram of the various receptors of a nerve ending (Mense 2010).

For example when the skin is damaged by sunburn the pain tolerance of the nerve endings is lowered so that taking a hot shower causes significant pain. Taking the shower is not actually causing any further tissue damage, but the tissue’s threshold is now much lower.
When is pain helpful and when is it not?
This lowering of pain tolerance is useful in the early days of an injury so that we ensure tissue loading is well below tolerance load and healing is allowed to take place. As healing and tissue repair take place the tolerance threshold should rise back to ‘normal’ levels.
But this doesn't always happen.
Researchers have built up a good body of knowledge relating to the phases of tissue healing and repair and how long damage takes to repair under optimal loading conditions. We have a pretty good idea how quickly your injury should heal.
Sensitised Tissue
However the pain threshold can remain lowered even though full healing has occurred. The tissue is said to be sensitised. In this state pain messages continue at levels of load and stress that are not causing further damage and would have previously been fine.
·        This can also occur during healing if the pain tolerance doesn’t rise again in tune with the tissue getting stronger.
As the tissue remains sensitized and reports “false” pain the nerve endings adapt in another way. The number, density and sensitivity of nerve endings increase. There are more receptors to be stimulated by a given stressor and the pain messages sent to the brain are greater.
In sensitised tissue the lowered thresholds and increased number of receptors result in the tissue losing its capabilities as an early warning system and significant pain is produced even when loading is well below damage threshold.
Sensitised tissue e.g. the achilles, can be sore to touch, even though there is no actual tissue damage.
How do we treat sensitised tissue?
Applying sensible loading to sensitised tissue stimulates cellular responses which promote both structural change i.e. strengthening, along with lowering of both the number of nerve endings and their sensitivity.
The terms Mechanotherapy and Mechanotransduction are often used in this context.
Mechanotransduction refers to the process by which the body converts mechanical loading into cellular responses. These cellular responses, in turn, promote structural change. Mechanotherapy is then “the employment of mechanotransduction for the stimulation of tissue repair and remodelling.” Simples.
Case study – Recovering from a stress fracture in the fibula
A runner presented with a stress fracture in the fibula. After three weeks of initial rest from running the fracture site was pain free. We then closely managed a slow build-up of tissue load through running. Initially, after each increase in run length, the injured area was tender to touch and ached. We listened to the pain feedback to optimise the loading recovery programme. After eight weeks the runner was back to full training. Bang on target.
Case study – Poor initial management of a hamstring injury
A runner presented with an overloaded hamstring tendon – classic case of too much too soon. There had probably been structural damage but this was poorly diagnosed and treated. No guidance on loading levels was given. Subsequently the runner yo-yo’ed between resting, but not enough, then running for thirty minutes, which was too much.
I first saw the patient six months after the initial injury. At this time the hamstring was still weak and sensitised. We undertook a gradual loading program but this was difficult due to the sensitisation – the runner felt pain even though no tissue damage was being caused.  Even when the hamstring was as strong as the other leg there was still pain with running short distances. We then worked to reduce the sensitisation through a running-based loading program.


Muscle Pain - Understanding the Mechanisms Siegfried Mense, Robert D Gerwin (Editors) Springer, 2010

Friday, 1 May 2015

A Tale Of Two Calves

Him indoors is always complaining about his calf. And, whilst Mr B may not be the swiftest runner, he compensates for the lack of a in Newton’s second law with an excess of m. F = ma indeed.

Calves and Achilles can cause real problems for runners. But there is hope, even if you’ve been troubled by ongoing calf problems for a long time.

With care it’s possible to run and race through overload calf injuries where there are no signs of damage if you know under what situations and conditions they are vulnerable. For those with repeated or longer term problems a structured loading program can improve matters greatly, as long as it’s done with discipline and common sense.

In this blog I’d like to outline my reasoning backed up with a couple of local case studies - Charlie Adams and Pete Gorvett - by way of example.

Charlie Adams grinds it out at the British Orienteering Championships 2015


Calf pain is very common in runners, particularly as we get older. Whilst there is a lot of scientific research published on muscle tears in the calf there is much less literature on ongoing calf pain where there is no significant or obvious tissue damage.

We see a lot of patients who don’t appear to have torn their muscles but for whom running is too painful.

In such cases it is hard both for the runner and the medical specialist to know how bad things really are. Muscle tightness and pain tend to be the main indicators but there is little evidence that either are correlated closely with actual damage.

Scans can of course be useful but they may not be decisive and will often show changes which may be perfectly normal and completely unrelated to the pain and problem at hand. Results of scans must therefore be interpreted carefully and logically.

Understandably physiotherapists will tend to err on the side of caution. If the patient is reporting too much pain to run then, for many reasons, it is unlikely the physiotherapist is going to encourage them to do so. For many years that was one of my guiding principles.

However there were some nagging doubts, reinforced by my own experiences as a runner, where I knew that in some circumstances it was possible “run through the pain.”

In the good old days of the Four Yorkshiremen, French and Saunder’s Stuff and Nonsense and the Black Knight’s “Tis but a scratch” running through injuries was common and worked for many. So maybe there is something in it.

Whilst researching the issue I read an interesting book - Muscle Pain - Understanding the Mechanisms Siegfried Mense, Robert D Gerwin (Editors) Springer, 2010 - which helped explain what we know about muscle pain and what we don’t.

In particular pain is governed by a complex system and there is a poor correlation between the amount of pain and actual damage to the body. This is a topic I’ll go into in more detail in later blogs.

I began to wonder whether in some cases an overcautious physiotherapist could instil risk aversion and fear in runners which in turn could lead to poorer outcomes.

Of course this does not negate good diagnostic practice where the most serious conditions must be considered and ruled out first.

My experience since then has been that with some calf problems running through the pain can be successful. I would caution that this requires an experienced and skilled assessor and a patient that is sensible enough to do it but not overdo it - and we all know how easy that can be.

For ongoing, long term or repeated problems, the “rehabilitation” process is similar, gradually strengthening the muscle and building up the load. There are two benefits
  • the muscle gradually becomes stronger and able to cope better with the loading required for the specific activity
  • the pain system gradually downgrades the sensitivity associated with that muscle.

Doing too much could reverse the process, potentially injuring the muscle or increasing the sensitivity of the pain system so it seems as if there is more pain.

The winning South Yorkshire SuperVets team - Nick, Charlie and Pete at the JK Relays 2015
(Photo courtesy of Rob Lines)

Case  Study: Pete Gorvett

Pete is a regular with Dark Peak Fell Runners and South Yorkshire Orienteers. He is currently ranked 2nd in the National Orienteering Rankings for the over 65s.

In the 2015 Wolf’s Pit race his left calf ‘cramped’ on the climb. After slowing down he managed to finish the race. He limped for two days then the pain started to ease.

On day three we met for an assessment. He was walking freely, able to go up on tip toes on his left leg but was aware of his calf.

The recommendations were to walk lots, swim, bike, and do some calf raises, holding the position for a few seconds to work the calf a bit. Once pain free with these activities he should try a short run.

A week later thirteen minutes flat running was fine but a slight hill led to tightening again, which led to a re-occurrence of the slight pain when walking.

It was now only five days to the Jan Kjellstrom trophy - one of the most prestigious orienteering races in the calendar.  At this point there was no purpose in further testing.

He was advised not to run until the race, not to the run the sprint race on the first day as short-fast urban racing puts a greater load on the calf, but to run the two forest races and to just go for it.

The terrain for these races was as rough as it gets - steep, muddy, rocky Lake District woods. Strangely these are ideal for nursing a sensitive calf as each foot strike and load is different and there were no sections where high running speeds were achieved. Had his goal been a 5km Park Run he’d have been advised not to race it.

Pete Gorvett on his way to becoming JK Champion 2015
Pete was aware of the calf on the first day, raced better on the second day, and won - beating the top seed in the over-65s who is ranked 100 places ahead of him in the open rankings.

Case Study: Charlie Adams

Charlie has been a top ranked orienteer for as long as there have been rankings and has won many major titles. He is currently ranked 3rd nationally in the over-50s.

For more than five years now he has suffered repeated calf and Achilles problems in both legs. He has had lots of advice and treatment including strength work, massage, compression socks, orthotics etc.

For the last three years he has failed to finish the two-day Jan Kjellstrom trophy; in 2012 he tore his calf in a marsh on Day 1, in 2013 he didn’t start due to a pre-existing Achilles problem and in 2014 he injured his calf on the Day 1 sprint race and couldn’t run days 2 and 3.

For the first years I treated him with the standard physiotherapist’s tools - massage, exercises and in later years running load management.

As the issues continued both Charlie and I became more frustrated, Charlie especially.

In the spring of 2014 I thought hard about why there was no progress. What am I missing? What more can I do? What more can Charlie do?

The pain: the level of discomfort seemed out of proportion to the level of damage. There was no sign of a significant calf tear but he was still unable to run for weeks at a time and any attempt led to pain walking again.

What is the cause of this problem such that it keeps happening? I had investigated all biomechanical aspects. Yes, he has funny feet and a distinct running style but orthotics and running technique correction had not helped.

What does Google say? A search of research papers and blogs revealed very little information on this type of problem. I did find a reference to the Mense/Gerwin book and reading that started to help me answer the first question - leading to Charlie’s famous ‘its all in my head’ post on his online training diary.  

Tentative Conclusion? The bottom line of all my research and reading was that Charlie’s calves were no longer strong enough (or the brain didn’t perceive the tissue to be strong enough) to manage the significant loads his strong fit body could put through them during an orienteering race - or even a training run. He had by this time had extensive time out from running in the previous years but when he did run he still ran at a fast pace which put high loads through the calf.

What to do? We agreed on an extensive long term (two-year plus) program of strength work alongside a managed running program of three to four runs per week, slowly building duration, speed and surface. Thankfully Charlie had the discipline to stick to do the boring exercises, and logged them online to help keep to the routine. He also saw a masseur for regular calf massages when he felt the tension was building. I kept an unofficial eye on his training diary and we discussed things informally at races as well as formally during appointments.

Progress: Seemed steady and generally upward. There were a few blips but the more advanced knowledge of the pain system gave me the confidence to believe all was going to be well and to communicate that.

Setback: The first, and to date only, major obstacle to date occurred just after New Year away running with friends. There was an acute onset of pain and tightness whilst running with no obvious or dramatic cause.

Confidence: It seemed as if we were back to where we were exactly a year ago. This time however I felt confident that this innocuous event had not caused more damage to his calf and that the over sensitive nerve endings had switched into hyperdrive again. Charlie would get better quickly and would be running again in two weeks. I did my best to reassure him that he would be running the JK.

More Progress: Things panned out as I said and training continued with minor soreness in the achilles and calf only and no periods without running.

Sensible approach to racing: Charlie adopted a sensible approach to racing - taking short flat Sprint races at a steady pace and concentrating on racing at full speed in the forest when it was important to do so. Like Pete he also missed the JK sprint to concentrate on the more prestigious  two day forest trophy.

Result: Charlie finished the JK for the first time in four years - and, being Charlie, won. He also anchored the South Yorkshire team to the National Relay Title at the British Championships two weeks later.

Going Forward: Continue to build load-specific strength and slowly build tolerance to faster road running, acceleration and deceleration so he can return to sprint racing as well as longer forest races.

The author, injury free, also managed to win her age class...
alas now practicing what she preaches for a grumpy calf following the Sheffield Half Marathon!

Friday, 6 March 2015

Remote Physiotherapy Service

Kim Baxter & Associates is launching a new remote-physiotherapy service aimed at runners of all types (road, fell, ultra, orienteering). In this blog I describe how my past experiences and recent thinking have led me to believe this can be a valuable offering.

I’ve been a competitive runner since I was a child, and have had my fair share of injuries, including an ankle ligament reconstruction. My most recent injury was last year, in my foot. It put me out of the Sheffield Half Marathon, my goal for the year. As ever, I didn’t follow my own advice - I pushed too hard in training and then didn’t listen to the warning signs as things started to unravel.

After fourteen years as a GB Orienteering Squad member I joined British Orienteering as physiotherapist for the Junior Squad in 2007, under the then Performance Director Gareth Candy, and moved to lead physiotherapist in 2009. At this point we both felt that the squad physiotherapy intervention needed to change from being based on physical presence i.e. at squad weekends and competitions, to be more generally available. Athletes would tend to wait until a squad weekend to get their injury assessed. We wanted athletes to become much more proactive in their injury management.

Injuries are a time where athletes face many negative emotions - fear, doubt, worry, even depression and grief. I felt an important part of regular contact with the athletes was to support them through these difficult times.

Initially our longer term goal was to build a network of “approved” physiotherapists based around the country that were available to provide diagnosis and treatment at short notice.

What I hadn’t realised at that point was the prevalence of online training logs, the fact that many Squad athletes were using them, and, after a suitable period of building trust, might even be happy for me read them. This allowed me to be more proactive in contacting them when they started with an injury and also allowed me to more closely follow their progress.

In 2010 and then for the whole of the 2012/2013 season I collected data that included training hours and the number of days training lost due to illness or injury for most of the Squad athletes. It would be entirely inappropriate to label what I’ve been doing scientific and the results don’t stand up to that kind of scrutiny. Throw in personal bias and placebo and you’ve little more, in scientific terms, than a suggestion of an area where further research might be fruitful.

However I have to work with what information I can get and the information was revealing. Whilst athletes were in general training at a high level the average time lost through injury and illness was astonishingly high. This was evident through the winter months November to January but also showed following the stresses of major competitions.

This started me thinking more about how their training might be affecting their injury and illness levels.  

How has my thinking about injuries changed?

Much of my education has focused on the intrinsic factors for injuries - biomechanics, the structure and movement of the body, and associated theories such as core stability, functional stability and muscle imbalance. Extrinsic factors such as training load, specificity of activity, equipment and surface were only covered in passing.

The general idea is that improved biomechanics will reduce injuries and your injury, when not caused by falling on slippery ice, has been caused by imbalance in your biomechanics. Rectify that and the injury will go away.

At some point many of us will have been told we have weak gluts, tight calves, a weak core or tight hamstrings, or that we over-pronate, supinate, have poor hip control or weak inside knee muscles. It may have been me that told you these things.

And of course it’s probably true, we probably do have these things when they are diagnosed and they probably do have an effect on injury development. But are these the factors that really tip us over into injury?

I’ve seen patients with relatively good biomechanics get serious long-term injuries through overtraining, and I’ve seen patients with terrible biomechanics who have been running competitively for years and only recently come to see me with their first real injury.

The concept that load as opposed to imbalance is an important factor in injury development is gaining ground. I’m using load in a very general sense. It could mean a breaking load that causes an acute injury, load applied over a long time that causes progressive breakdown, or a variation in load e.g. suddenly running on roads when you’ve been training on the fells.

Obviously acute injuries sometimes happen - there is not necessarily a lot that can be done, but the other two types of load can be managed. For one, recovery-time between loads is important, for the other common sense is quite useful.

But, if you are anything like me, sometimes common-sense needs external input.

I believe the biomechanical analysis and approach is valid in many ways and there will always be patients where it is the most significant factor. But if I’m having to hunt to find a significant biomechanical issue then I start to question how much of a factor is it?

The difference in thinking about loads is that it is much simpler. If your body is strong enough to resist the required load it doesn’t matter if you are biomechanically unsound. Sure, all things being equal you would perform better if your biomechanics were better, but it doesn’t mean that is the best route to avoid injury.

A nice example are climbers, who tend to be have very good core strength and excellent movement patterns through the biomechanical chain. They often present with better strength and control than many seasoned runners. They also often like running, but in my experience they tend to break pretty quickly when they start running seriously, simply as their bodies aren’t used to running specific loading.

Put in simple terms, I believe many injuries can be overcome through a managed programme of activity-specific strengthening and many injuries can be prevented through appropriately managed training.

Something as simple as just being sensible.

I recently helped a 60 year-old patient who was injured after walking a 50 mile ultra-race. He told me he was “getting too old for this”. I remembered he had recently completed a 60 mile run for his 60th birthday. A few questions later he realised that the latter was in  hilly terrain, he was used to running long distances and he had trained for it, the former was walking, on the flat, and he hadn’t prepared. It didn’t seem as if age was the most significant factor.

How has this changed my approach with British Squad athletes?

I now focus far more on trying to spot training errors. For example, too many hard sessions without recovery, sudden increases in training, sudden variations in training or activities, even just athletes starting to sound tired.

Dealing with injuries has also changed. I now focus much more on helping the athlete to find the right load levels to allow the injury to heal and the supporting structures to strengthen without further aggravation. Sometimes this can mean suggesting they back off, sometimes it might mean giving them the confidence to push a little harder.

With online training diaries and free video-conferencing tools such as skype this approach to injury prevention and rehabilitation can be done almost as effectively remotely as face-to-face. It is based on developing an understanding of the athlete’s goals, training, lifestyle, activity levels and the external and internal stressors they have to overcome to reach them.

If you want to learn more take a look at the Remote Physiotherapy FAQ on

Wednesday, 28 January 2015

Running in Winter Conditions

With Sheffield Park Runs cancelled last week and more winter weather on its way its worth thinking about how to avoid injury when the roads are covered in snow and ice.

Every year we see injuries caused by changes in loading due to running on snow and ice. Typically affected are the the feet, back and hips. Even Elite orienteers who do much of their training in heavy terrain can quickly develop overuse injuries when suddenly doing a lot of running in deep snow.

(Photo by Dave Peel, Explorer Events)

Ice is both hard and slippy and both have an effect on the loads through your body. The harder surface combined with changes in footwear to increase grip mean more impact through the feet and body. And no matter how grippy your footwear your whole body will be working harder to provide the extra control and stability.

Softer snow tends to be easier, particularly if you run off-roads regularly, but you need to push off harder with a higher knee lift and this works the hips, pelvis and lower back harder. Melting snow or thinner coatings of soft snow can also be very slippy.


Veteran Road Runner, Equipment Geek and Bambi-on-Ice Paul Faulkner, has, as usual, tested the commonly available options.

If possible he suggests using shoes with grips, which for ice means attaching something like Yaktrax Ice Grips to your existing shoes, or buying a pair of shoes with metal studs built in such as the Inov-8 Oroc 340s. Paul advises that for soft snow normal footwear is fine, but using Yaktrax is better. On ice Yaktrax still function but purpose-built shoes such as Orocs are better.

If there are only patches of ice then running long distances with metal studs is likely to do more harm than good so it’s a question of using normal shoes and dodging the ice as much as possible.

If you aren’t confident then slow down, take shorter steps on icy sections, run on trails rather than roads where the ice tends to be broken up by the terrain, and run on grass at the side of roads and paths rather than on the tarmac.
Overuse Injuries

Anytime you vary your training you are at risk until your body adapts - so for most people snow and ice means increased risk. The best advice is be sensible - consider adapting mileage goals and reducing your hours training. Also consider:
  • Leaving extra recovery time between runs or sessions, particularly if you are feeling sore or tight from a previous run
  • Stretch and foam roller tight calves, feet, hips and back
  • Consider doing harder runs on a treadmill, noting this is also a change of surface
  • If possible cross-train - perhaps try biking on a turbo trainer, a spinning class, swimming or aqua-jogging.