First of all, let’s start with the basics.
Injury occurs when the body is exposed to forces that it cannot process, manage or disperse, and are subcategorised into ‘Overuse’ & ‘Acute injuries’ (or ‘micro-trauma’ and ‘macro-trauma’).
Performing repetitive actions with poor technique, at regular intervals, may repeatedly overload the structures of the body, minimally, but repeatedly. This regular exposure on the muscles, bones & joints (etc.) result in micro-trauma, as the structures struggle with the repeated micro damage, but fail to repair and regenerate fully, before being re-exposed. This is what is termed Overuse Injury.
There are a number of factors involved in developing an overuse injury, as detailed below (see Fig1.) but ultimately the exposure to overload, exceeds the time required for repair resulting in damaged tissue.
Understanding the WHY behind the onset of overuse injuries is the biggest challenge for your therapist, and is where our investigative skills come in to play!
Fig 1. Risk factors of overuse injuries
Predisposing Risk factors for overuse injuries can also be considered as Extrinsic (something external to the body that can cause injury) or Intrinsic (being factors internal to the individual person) Fig 2.
The second mechanism of injury is an acute exposure to stronger forces that acutely overload the structures beyond their capacity, moving them in a way they are not designed to move, or exceeding their ability to transmit the forces they are exposed to, resulting in macro-trauma or an acute injury.
Fig 2. Extrinsic & Intrinsic risk factors to overuse injuries
But it's not always that simple !
(that would be boring wouldn’t it!).
The body is a complex machine, and therefore, understanding the mechanism of injury and locating the source of pain is not always a nice yellow brick road to follow.
Pain may not necessarily be coming from the site where it is felt. Referred pain needs to be considered, as does the much more complex phenomenon of chronic pain.
Some medical conditions can masquerade as injury, with mimicking signs and symptoms so discussing your case with a qualified therapist is very important for not missing any red flags, and loosing time to seek medical advice. If an injury remains unresponsive to treatment, seeking a second opinion or seeing your GP for further referrals is always advised.
The area of pain may not be the area of dysfunction! In order for movement to occur smoothly, under full control and in a stabilised manner, the whole kinetic chain must work as a coordinated unit, with the separate body segments, or “links” (above and below the limb actually moving and functioning) all moving in smooth and co-ordinated sequences, starting from a proximal base of support (or stability). This coordination throughout the kinetic chain results in a cumulative effective transfer of force and energy, resulting in controlled and efficient body movement and ultimately safe and effective movement. A “kink” (injury or dysfunction) anywhere along this chain can result in excess strain or loading/over compensation (& therefore injury) to any muscle group/ or body segment further up or down the chain. This is why rehabilitation exercises, and taking responsibility of your own injury is so key in a successful outcome – a therapists’ “hands on” treatment can be an excellent modality in your treatment journey, to ease out tension, release trigger points, stretch contracted muscle, break down scar tissue etc., but ultimately we cannot change how your body moves and stabilises' itself (which is why I like to give exercises to all patients presenting with ongoing or acute issues and why I always encourage ((nag)) for you to do the exercises I set!) (It’s not just because I have turned into my mum).
With this is mind, let’s consider how the body moves when running.
The Biomechanics of running
The biomechanics of running is a combination of movements, swings and foot strikes that can be analysed and considered in sections when considering potential trigger factors for running related injuries. Certain abnormal biomechanics have been clinically associated with certain lower limb injuries – and in my future blogs in this Running Injuries Series some of these will be considered – but the science of biomechanics is advancing with some research supporting these clinically noted associations, and some suggesting there is more to consider.
In simplistic terms, running with optimum body mechanics should enable the kinetic chain to function effectively and transmit forces efficiently enough to not cause over or mis/dis use.
For example, free from excessive motion or restriction (which may cause asymmetrical mechanics and impact somewhere along the kinetic chain) the forces moving though the body should be transmitted effectively, reducing the risk of injury. Now saying that, and completely contradicting myself! we must always consider that each individual has his or her own mechanical make-up and “normal” (due to structural characteristics), so variations will and do occur. Although one person may have excessive “flat feet” (over pronation) they could be symptom free and never have had any issues, meaning although they don’t fit the text book profile of “ideal biomechanics”, we can’t consider their biomechanics to be somehow dysfunctional if they are injury free.
To briefly explain the biomechanics of running it is, similar to walking, broken down into stance and swing phases. The stance phase is divided into contact, midstance and propulsion. The swing phase divided into follow-through, forward swing and foot descent. Unlike walking, there is a “flight phase” with running, when neither foot has contact with the ground. These stance, flight and swing phases change in duration depending on the speed of running (jogging/sprinting), as does the portion of the foot that strikes the ground on landing.
It are these considerations that may be taken into account depending on the injury you present with, for example depending on your style of running you may be landing on different aspects of your foot, or your swing time and rhythm may be different or may be affected by commonly clinically associated muscular tightness/dysfunctions.
Now, finally, in our journey to understanding the concept of running injuries a little bit better, before moving onto specific body areas, and injuries commonly associated with running in the weeks to come, let’ s consider quickly the phenomenon of pain.
Pain is not an accurate indication of tissue injury or damage! Yes, there are many pain-producing structures within the body that contain nociceptors (the receptors that “feel pain” and transmit these pain signals to the brain), but sometimes pain is reported without any detected localised damage or dysfunction, and sometimes pain is ‘referred’ to distant areas
Nociceptors (the pain receptors) can be “fired up” by chemical irritation (as present in inflammation in response to injury), and also by localised muscle spasms in response to an injury, or later, from fibrosities and scarring occurring from an injury repair. This type of pain response is seen in acute pain presentations and has a clear physiological founding. Now remember, pain is not transmitted from the site where you feel it, in fact pain is a message from the brain, in response to sensory information it receives, and then responds to (be that information be changes in chemical levels / pressure / stretch on the tissues at the area affected, changes in temperature, but also other sensory input such as sight / sound / touch).
Although pain is a useful and vital mechanism to prevent further harm and injury, pain can sometimes be present without any clear tissue damage, and when you enter the realms of chronic pain, things can get a lot more confusing. Patients with no pain can image (XRAY/CT SCANS) with clear disc protrusions or disc ruptures in the lumbar spine, yet be completely unaware of their physical presentation as they are pain free and functioning well. Therefore, pain is not a clear indication of lumbar vertebral issues with these patients. Which leads to question where is the pain coming from and why is it there? Similarly, patients with Limb amputation can still experience pain in the limb that is no longer there. If it is not from damaged structures, then what has caused the brain and central nervous system to overdrive pain signals? And how can this impact of the diagnosis and management of injury?
Pain that has been present for more than 3 months is classified as chronic pain, and given that most structural injuries have “healed” within 3-6 months, this persistent pain COULD be attributed to more complex factors. It is important to consider the pain is coming from an over-sensitised nervous system, and there are many factors that could impact on that, to include;
So, as you can see, as I plan to move into more regional pain patterns and injuries associated with running, there are many different factors that may come into play with their management and resolution. However, I hope this has pointed out some of the main pointers that I, as your therapist, is considering when you present with a niggle, and how you can become responsible for your own rehabilitation and injury resolution.
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Fanatic about functional anatomy, my home often resembles a students dorm room with anatomy and therapy text books strewn about on a regular basis. I like to keep abreast on the industry, and when time allows between mummy-duties, I read trade magazines, books and journal articles, to help me prep & plan treatment plans & rehab.