Has someone told you your injuries are due to a leg length discrepancy? It can be a concerning, dis-empowering thought for any runner. But do athletes need to be concerned? Let’s look at the research to find the answers.
A paper titled ‘Methods for Assessing Leg Length Discrepancy’ found that without scans, the most reliable method to determine leg length is to measure the distance between the hip bone (ASIS) & ankle bone (medial malleolus). However, a CT scanogram is reported as a sensible alternative when considering accuracy, cost and radiation exposure.
If a runner is found to have a leg length difference with accurate testing, then they share this finding with 90% of the population. That’s right, 90% of humans (with studies including 2.68 million people) will have some form of leg length difference. Additionally, research then found the average difference was 5.2mm and deemed insignificant.
A leg length difference under 20mm is not likely to cause symptoms that require treatment and reviewing these massive population studies, only 1 in 1000 show a difference greater than 20mm. Then reviewing the research findings above, this would fit our current understanding of running injuries, because our body does an amazing job at adapting to a wide range of running styles. As a result, we should focus on load management and avoiding rapid changes so our body can adapt and stay healthy, rather than handing our control over to a false, dis-empowering narrative.