I have long suggested that the cause of an overuse injury in runners is the cumulative load in the tissues is beyond what the tissues can take, so the management is simply one of load management by reducing the load and/or increasing the ability of the tissues to take the load. Most assumed and identified risk factors are associated with either the increased cumulative load or the decreased ability of the tissues to take the load. Using evidence to identify those risk factors is problematic due to the extent of the evidence that is available and the choice of which risk factor to investigate in the prospective studies (only so many variables can be tested at one time). This was illustrated in the most recent systematic reviews of the risk factors:
What are the Main Risk Factors for Running-Related Injuries?
Bruno Tirotti Saragiotto, Tiê Parma Yamato, Luiz Carlos Hespanhol Junior, Michael J. Rainbow, Irene S. Davis, Alexandre Dias Lopes
Sports Medicine; May 2014
A total of 11 articles were considered eligible in this systematic review. A total of 4,671 pooled participants were analysed and 60 different predictive factors were investigated. The main risk factor reported was previous injury (last 12 months), reported in 5 of the 8 studies that investigated previous injuries as a risk factor. Only one article met the criteria for random selection of the sample and only six articles included a follow-up of 6 months or more. There was no association between gender and running injuries in most of the studies.
The main risk factor identified in this review was previous injury in the last 12 months, although many risk factors had been investigated in the literature. Relatively few prospective studies were identified in this review, reducing the overall ability to detect risk factors. This highlights the need for more, well designed prospective studies in order to fully appreciate the risk factors associated with running.
I didn’t post the full abstract (its here) as it just contains the usual information you get about systematic reviews. This systematic review only focused on the more powerful prospective studies rather than the less powerful cross sectional correlation studies. The systematic review pretty much confirmed what we already know, that the greatest risk factor for identifying those at risk for injury is a previous injury. This factor was identified in most of the studies they included in the review.
The other findings of the review were:
- a previous injury in the last 12 months was found in 5/8 studies that investigated this factor.
- a higher quadriceps angle of the knee (Q angle) was associated with running injuries in 2/3 studies.
- weekly distance as a risk factor identified that training for more than 64 km a week was a risk factor for lower extremity injuries in 2/5 studies
- a relationship between weekly running frequency injuries was found in 2/5 studies
- One study found that running three to seven times a week was a risk factor for running injuries in men and that running seven times a week was a risk factor for women.
- Gender was not associated with running injuries in most of the studies.
A shortcoming of this review (though not an actual fault of the authors) is that it just looked at all overuse running related injuries. Its highly likely that each individual injury will have a different set of risk factors and a different weight given to those risk factors. It just highlights the lack of evidence that there is in this area as there are not an abundance of prospective studies that meet the methodological criteria to be included in the review.
As always, I go where the evidence takes me until convinced otherwise.
Saragiotto BT, Yamato TP, Hespanhol Junior LC, Rainbow MJ, Davis IS, & Lopes AD (2014). What are the Main Risk Factors for Running-Related Injuries? Sports medicine (Auckland, N.Z.) PMID: 24809248