Ever wondered why you keep getting injured?

More often than not, pain and injury comes out of nowhere and as much as you scratch you head looking for reasons you just cant find one..

We call these insidious onset injuries or spontaneous injuries, as a opposed to traumatic (which may instead result from a fall or motor vehicle accident).

To understand why and how these insidious injuries occur we must take a look at a concept known as load tolerance.

The phrase “load tolerance” is something that you will hear frequently used in our physiotherapy clinic. But what does it really mean?

Load tolerance is determined by two factors , the “load” and the “tissue capacity”.

The load (or Loading) refers to the demand placed on the body, it is the intensity of the task that we are doing, it can be related to the force exerted or the weight lifted or resistance overcome. It is also the frequency, the duration or the distance of the task being completed.

Tissue capacity refers to how our body copes with the demands placed upon it. With regards to tissue capacity we are specifically referring to how our bones, ligaments, muscles, tendons, joints, discs and nerves respond to load. This is dependent on your own natural physical attributes (how you are made), your biomechanics (the way your body works), strength, flexibility, endurance, movement efficiency and movement options or choices (often these are limited by the former factors mentioned).

When we exceed our tissues capacity to tolerate a given load, we bring about stress and trauma to a body part. This in turn leads to inflammation which we experience as stiffness, pain and injury.

So how can we reduce and manage pain and injury?

Once again looking at load, we must ensure that we are working, training or carrying out a task that is appropriate for our level or ability. Exercise and activities (loading) should be gradually progressed, they should be varied and realistic (consider your abilities). It’s essential to incorporate rest during and after the task, to allow tissues to recover and be ready to perform again.

With respect to capacity it’s important to add strength and conditioning into our lives to ensure that our muscles are strong and conditioned in order that they may cope with the tasks and demands placed upon them. Strength and conditioning goals will vary and be very dependent upon the tasks and activities that we aim to complete.

Variation of movement or tasks decreases the demands and repetitive stresses and strains on our body. Once again ensuring that you have adequate rest in the form of sleep to allow tissues to recover is essential when managing capacity.

Optimising movement is key to moving in an efficient manner. Biomechanical assessment or movement analysis enables us to learn new or modified movement patterns, which result in spreading/sharing the load across regions of the body rather than it being focused on one specific area, that may after time succumb to load and insufficient capacity.

Lets now use an example to examine load tolerance.

Example 1
After a 12 month break from exercise John decides to take up running. He starts by running twice a week aiming to complete 2km per run. After 3 weeks he feels so good that he decides to increase his running distance to 5km and to add a further run at the weekend, as his friend tells him that most runners run three times per week.

After a further 4 weeks he begins to feel stiffness in his achilles. He continues for a further 2 weeks but by then his achilles is so painful he is required to stop running and seek help.

In this case the load is the running distance, frequency and intensity he puts in. The tissue capacity relates to John’s strength, flexibility, endurance, technical ability and movement options.

Where did he go wrong?

Load
Firstly starting at 2km was possibly too great a distance. An initial programme of walk/run over a 1km distance may have been more appropriate (see the couch to 5K plan here: https://www.nhs.uk/live-well/exercise/get-running-with-couch-to-5k/).
Ideally running distance should be increased incrementally by 10% per week
Adding an extra day on top of increased distance has undoubtedly exceeded optimal loading
Tissue Capacity
A formal biomechanical analysis to detect running faults and provide specific retraining exercises would facilitate optimised movement and reduce tissue stress.
Some specific strength and conditioning drills carried out three times per week would aid tissue capacity.

Example 2
Julie has recently returned to work after being off on maternity leave. Her new job as a warehouse assistant requires her to be on her feet all day whilst moving and lifting boxes. Four weeks after starting Julie notices that her lower back starts to hurt. Over the next few weeks she finds the pain increases to the point that she needs some time off work

In this example we see a sudden change in load in that she is on her feet for longer than normal,carrying out new tasks that require strength and agility and endurance (lifting boxes). She is also likely to be resting less through the day and is faced with looking after family on her return from work in the evenings.

What could have she done differently?

It is always difficult starting a new job, but having an understanding of what lies ahead can ensure better preparation. In an ideal situation Julie could have ensured that she was walking 1-2 hours per day to adjust being on her feet at work.

She could have prepared her body for the lifting that was to come through strengthening her arms, trunk and legs with strength and conditioning exercises at home or in the gym (optimising tissue capacity).

Ensuring that she is skilled in moving and handling heavy boxes through manual handling training will protect her from overloading her spine (optimising tissue capacity). Finally ensuring that she gets adequate rest in the evenings and overnight will help her body recover from the days stresses and strains (optimising tissue capacity).

Insidious pain and injury

Hopefully this gives you a better understanding of load, tissue capacity and how this relates to load tolerance. It is essentially these factors that often determine when, why and how we sometimes succumb to pain and injury.

So when you next wake up in pain and can’t remember what you did, think of the previous days and weeks activities, did you do something above and beyond what you would normally do (this could quite easily be  sitting more than usual at your PC or on the couch over the holidays as opposed to a much longer run than normal).  Its easy to think you did nothing, slept in a draft (which by the way doesn’t cause pain) or  slept awkwardly, when in fact its the fact that you exceeded your load tolerance! [author] [author_image timthumb=’on’]https://sportsandspinalphysio.co.uk/team/[/author_image] [author_info]Dan Smith BSc (Hons) MCSP is the Director and Clinical Lead at Sports and Spinal Physio. He has a special interest in neck pain and headaches. [/author_info] [/author]

Based on Physio Edge Podcast 059 with Tom Goom, Dr Christian Barton and Greg Lehman