The most common class of injury caused by running is that of overuse. So unless you’ve managed to step in to a pothole or tweaked your hammy at that speed session, there’s a very high possibility the pain you are feeling is a result of overload. Pretty obvious considering what we are generally dealing with is a repetitive task of putting one foot in front of another time and time again, and usually for several days in a week.
Some interesting stats to be mindful of:
If you are running 12 km/hr, the average man probably takes roughly 1400 steps, and the average woman around 1500 steps per kilometre. So multiply that by the kilometres you do in a week and you’ll start to get a feeling for how much demand is being placed on those tissues that make up your lower limbs, pelvis and back.
The ground reaction forces involved in running probably equate to 2-3 times your body weight. Now again multiply that by your steps and we now start to consider load, and the cumulative effect of it.
Load is the overall force exerted on a body or structure. Load is what our body’s tissue adapts to in order to improve its tolerance, but in the instances where load is too great for adaptation to occur, the result is pain (a normal response to impending or actual tissue damage).
Factors contributing to excessive load in overuse injuries:
When you walk in to our Clinic and we sit you down to talk about your injury, the following info is what concerns us:
1) Training Parameters (Intensity, frequency and volume)
How far/long are your runs and how many sessions are you cramming in (volume)? What type of training are you doing and how hard are you going (intensity)? These considerations, as well as how often you train (frequency), all impact on training load so adjusting one or the other will modulate it. As an example, speed sessions with high intensity should be short and generally infrequent (generally once per week for distance runners). Another example, your longest run should be around a third of your total running volume for the week, i.e. your involvements aren’t frequently high volume. In a nutshell, if one element is high, balance it out with the others.
Example of an intro training schedule:
Monday Cross Training (CT) (off feet – bike or swim) / stretch session
Tuesday Speed Session 2 x (3 x 400m run/walk interval)
Wednesday Rest or CT
Thursday 6 km race pace
Friday Rest / stretch / yoga session
Saturday 7 km
Sunday 5 km easy pace
TOTAL: 20.4 km of varied input
Rest days and easy days allow your body to recover. Scheduling it is a must.
2) Environmental Factors
Consider identical twins, Jane and Jill, in their early 30s training for a Marathon. Jane lives in Canberra and runs 30 km a week around the lake on flat bitumen. Jill lives in a hilly suburb of Brisbane and does exactly the same running program (volume, frequency and intensity). Jill, however, runs straight down a hill out of her front door. In fact, she tackles 4 decent hills on her 10 km running route. At times she has to run on the side (camber) of the road where there are no footpaths, sometimes on dirt and grass and other times on a path.
It doesn’t take a biomechanist to appreciate that Jill’s run is much harder than Jane’s because of the added environmental stresses Jill must overcome. The knees will be impacted by the increased knee flexion (bending) angles as well the eccentric quadriceps forces in the downhill portions. The medial and lateral (inside and outside) ligaments and tendons of the ankle will work harder to stabilise on the unstable surfaces and cambers.
The most important bit of kit a runner uses is their footwear. A decent pair of running shoes prescribed according to your foot type is likely to assist with attenuating forces more readily than your old Dunlop KT-26’s you’ve done the mowing in for the last 5 years. Most of the cushioning and stability components in a shoe are made from EVA, a fairly tough and somewhat elastic polymer, but just like your bones and tendons – bash them enough, they will wear. Most shoes will last up to 800km, so divide that by your weekly volume to get a read on your shoes’ shelf life. Keen runners may need to replace them as soon as the 6 month mark.
4) Biomechanical considerations
Probably the hardest thing for you to appreciate without having this formally analysed. Identifying these factors is what you are spending your money on whilst at Physio, so having a good one helps. Evaluating your gait, running pattern and your body’s ability to handle load is crucial to determining whether or not you have any intrinsic risk factors for developing an overuse injury.
Consider Jill and Jane again, but now Jill has decided to move to Canberra after a marriage bust up with Jack. The stress of that and the move has meant she’s packed on 10 kg of unwanted weight. Despite the fact that all other biomechanical and cardiovascular baselines were the same between the two girls 6 months ago, Jill is going to be more at risk of injury than Jane with a significant increase in her ground reaction forces. Now her hip stability fatigues early and causes her hip to drop, driving rotational forces down the limb through the knee to the foot. It’s no surprise her knee is painful at the 3 km mark now since the muscles, tendons and joints in her legs are under comparatively more load, tensile and now torsional.
Put your injury concerns to bed by asking yourself which of these four factors may be contributing most in your circumstance. There’s a 75% chance with some thoughtful reflection and careful planning that you might just be able to sort yourself out. If not and your symptoms still persist, come along and we’ll be happy to assist.
Chris Dillon, Sports Physiotherapist