I have to admit the the use of strength training for runners, especially to prevent injury is not something I have paid a lot of attention to. I am ‘old school’ and just want to go for a run. You train for running by running. I have been noticing more and more people talk about the usefulness of strength training for runners and there has been some research to show it might be helpful and other research that says its not, which is probably why I did not take a lot of notice to the conflicting evidence. I do listen to and read what people like Brian Martin have been saying about it, but (….and sorry Brian), I have to admit that I did not take a lot of notice of the concept. I always struggled to comprehend the mechanism behind how having a stronger muscle could help prevent an injury. How does being able to do a dozen deep squats with a heavy weight help in the last kilometer of a marathon? Overuse injuries are prevented by reducing the load in the tissue and adapting the tissue to take the load, so how does strength training help with that? The cynic in me was wrestling with these types of issues.
However, recently I noticed that whenever I try to do things like lunges and squats my legs are not like they were a few years ago (I do a ‘boot camp’ like group fitness class twice a week) and was started to get a bit concerned that something was wrong as my strength should not be declining with the exercise I was doing. Then this research turned up last month. It showed that when runners reach a certain age that they loose up to about 5% in muscle strength in the legs each year. I had reached that age, so no wonder I was struggling with the lunges and squats. Fortunately that meant that there was nothing wrong with me, it was just part of the normal aging process. It also meant I had better start paying more attention to the issue of strength training to supplement the running!
The problem I recall with what research I had seen on the role of strength training especially to prevent injury is that the data was not really clear one way or the other with some studies saying yes and some studies showing no. There were some strong studies and some weak poorly designed studies, so it could be easy for anyone to cherry pick a few studies to make whatever point they want to make. When this situation exists, that is when we rely on the systematic reviews and/or meta-analysis of all the studies. A search strategy is used to locate all the studies; then criteria is applied to select only the methodologically sound studies; then the data from them all is pooled to try and reach a conclusion and make sense of it all. Fortunately, especially in the context of the issues I am facing myself, such a review turned up this morning:
The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials
Jeppe Bo Lauersen, Ditte Marie Bertelsen, Lars Bo Andersen
Br J Sports Med doi:10.1136/bjsports-2013-092538
Background Physical activity is important in both prevention and treatment of many common diseases, but sports injuries can pose serious problems.
Objective To determine whether physical activity exercises can reduce sports injuries and perform stratified analyses of strength training, stretching, proprioception and combinations of these, and provide separate acute and overuse injury estimates.
Material and methods PubMed, EMBASE, Web of Science and SPORTDiscus were searched and yielded 3462 results. Two independent authors selected relevant randomised, controlled trials and quality assessments were conducted by all authors of this paper using the Cochrane collaboration domain-based quality assessment tool. Twelve studies that neglected to account for clustering effects were adjusted. Quantitative analyses were performed in STATA V.12 and sensitivity analysed by intention-to-treat. Heterogeneity (I2) and publication bias (Harbord’s small-study effects) were formally tested.
Results 25 trials, including 26 610 participants with 3464 injuries, were analysed. The overall effect estimate on injury prevention was heterogeneous. Stratified exposure analyses proved no beneficial effect for stretching (RR 0.963 (0.846–1.095)), whereas studies with multiple exposures (RR 0.655 (0.520–0.826)), proprioception training (RR 0.550 (0.347–0.869)), and strength training (RR 0.315 (0.207–0.480)) showed a tendency towards increasing effect. Both acute injuries (RR 0.647 (0.502–0.836)) and overuse injuries (RR 0.527 (0.373–0.746)) could be reduced by physical activity programmes. Intention-to-treat sensitivity analyses consistently revealed even more robust effect estimates.
Conclusions Despite a few outlying studies, consistently favourable estimates were obtained for all injury prevention measures except for stretching. Strength training reduced sports injuries to less than 1/3 and overuse injuries could be almost halved.
Nothing jumps out at me as anything being problematic in the way the authors did this review and their analysis of the data, except perhaps it did include sports other than running, but it did divide the studies into acute and overuse for the nature of the injury. The diverse nature of the included studies in terms of the exact nature of the interventions and the wide range of sports may be problematic in generalizing the results to any one specific sport.
The conclusions were quite clear and carry a lot of weight as a meta-analysis sits at the top of the ladder when it comes to the hierarchy of evidence:
- Stretching does not protect from injury
- Proprioceptive training and ‘multiple exposure’ programs were effective
- Strength training was highly significantly protective
Strength training decreases the risk for overuse injury by half, which is quite an important conclusion.
As always, I go where the evidence takes me, and it looks as though I going to be heading to the gym more for some lunges and squats!
Jeppe Bo Lauersen, Ditte Marie Bertelsen, Lars Bo Andersen (2013). The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials Br J Sports Med DOI: 10.1136/bjsports-2013-092538