Marathon Season Injuries: Part 5
We have been speaking about distance running and the associated injuries that are commonly seen. As we have discussed across the series of articles, the three main areas that are likely to contribute to the development of injury are biomechanical factors, training loads (volume, intensity, duration and frequency) and tissue and joint capabilities (strength, range of motion, power, elasticity).
In this article we will explore the most common biomechanical question that we have been receiving regarding running.
What foot strike should I use? Heel, midfoot or on the toe (forefoot)?
The answer is not always clear when it comes to footstrike. There is no definitive literature that describes the best foot contact strategy to use, however there is evidence that highlights that heel contacts may potentially increase the instantaneous vertical loading rates, and that alteration to a midfoot or forefoot strike may reduce this risk factor that has been associated with tibial stress fractures (Pohl et al 2008 and Milner et al 2006 and Willy et al 2016 and Yong et al 2018). As highlighted in our previous article, this impact loading is clearly visible in the work of Clark and Weyand, see video below.
So what do we do we recommend?
Running at a constant speed is typically a task that uses the elastic structures of the leg (tendon, connective tissue and fascia) to store and release elastic energy for propulsion. In order to do so and limit stressing one joint more than another (more at the knee, ankle or hip for instance), landing with the foot close to the line of centre of mass and on a larger base of support at contact is likely to distribute the forces more evenly across such joints. This in effect suggests that from a biomechanical loading point of view, the initial point of contact is not the only important factor (see picture below in elite runners showing all variations, image from IAAF biomechanical study 2017). If the point of contact is not exceedingly distant from the centre of mass and the full foot is used in the midstance/full support phase to assist with absorbing the weight of the body under gravity the forces are likely to be dispersed across more tissue.
It is therefore important to look at foot strike as a starting point for what occurs further up the chain, rather than it being an outcome. Each individual is likely to use this starting point and due to their individual tissue characteristics and capabilities will develop strategies to manage the ground reaction forces accordingly. In the event that a runner does not have the adequate capabilities then excessive joint movement occurs and the surrounding structures may be overloaded. If this is the case there would be potential for recommending changes to the landing position of the foot, however individual assessment is required.