Researchers in Denmark recently reviewed the current research on exercise programs for injury prevention, and crunched some numbers to see what does or doesn’t work.1 What did they find?
Strength training reduces sports injuries by about 68%, proprioception training reduces injuries by about 45%, and stretching programs do not reduce injuries reliably. Interestingly, combined programs only reduced injuries by about 35% (all of which included strength training).
My first thought is: “damn strength training, you crazy!” Cutting injuries down to one third… those are some great results! And personally, my bias is confirmed – I’ve always thought strength training was important for injury prevention, especially strains, but wasn’t too sure what the research said. The good results with proprioceptive training are not surprising - which in this review included “neuromuscular training”, involving exercises for balance, coordination, agility, stability, etc.
That strength training was found very effective may seem “obvious” in hindsight. But don’t forget that before it was shown that stretching doesn’t prevent injuries, it was considered “obvious” that it did (maybe it does for particular athletes like dancers – but that’s another discussion). Either way, it’s good to have stronger evidence. See what I did there?
Reviewing the Review
Before people throw out everything except strength training, let’s take a closer look at the studies reviewed. There are some important details.
Strength training was shown to cut acute injuries down to one third, and overuse injuries down to one half. However, it should be noted that half of the strength training studies used hamstring strengthening, and only measured improvements in hamstring strain injury occurrence, rather than overall injuries. This may have made strength training look better than it actually is for injuries in general.
Other exercise methods (especially combined programs) typically looked at overall injury occurrence. This may have lowered the apparent impact – certain types of exercise simply shouldn’t be expected to prevent every type of injury. Proprioception exercises generally worked better when they were more specifically matched to a particular outcome – like ankle stability exercises for preventing ankle sprains.
Finally, stretching programs typically consisted of static stretching rather than dynamic stretching - so the poor results aren’t surprising. Furthermore, athletes studied were typically involved in activities that normally do not require large amounts of flexibility. Most studies investigated team sports – soccer and basketball players mostly – and no study looked at athletes who use larger ranges of motion like dancers, martial artists, gymnasts, etc.
It would be great for further research to inform us which types of exercise prevent particular injuries. This way programs can be designed more appropriately, considering the risk factors of both the activity, as well as the individual.
Strength training was effective at preventing injuries, but how much strength is needed? Can someone become “strong enough”, how can we know, and is it significantly different between sports? Is it even the level of strength that matters, or perhaps the training itself “priming” the neuromuscular system to increase preparedness? These questions are difficult to answer and will require a lot of research.
Perhaps all methods work as long as they are appropriately applied. This highlights the importance of designing prevention programs specifically for particular activities, matching the exercises with the demands placed on the athlete. There is no one perfect injury prevention program for every person and every activity.
For those of you who are reading this just for the practical take-home message, here are some recommendations.
This is just my (informed) opinion, of course – and all recommendations should be adapted for individual needs and sport specific demands.
Warm-up for Training and Practice:
- Warm up with active, dynamic mobility exercises. Move through the range of motion you’ll need - if your sport requires a big range of motion / flexibility, and you don’t have this range yet, then sure, stretch (mostly after practice).
- Make sure your warm up also includes coordination training – anything that challenges balance / stability and agility, preferably during sport-specific movements.
- Include a few strengthening exercises (probably best to avoid fatiguing yourself) for muscles that tend to become strained in your sport – for many sports, this will be the hamstring and groin muscles.
Strength and Conditioning:
- Perform one or two strength training sessions a week, perhaps at the end of practices. Exercise the whole body – but sport specific needs should be emphasized.
- Perform conditioning exercises two to three times a week, perhaps at the end of practice. Improved endurance is correlated with reduced injury rates. Injuries often occur at the end of competition when athletes are most fatigued.
Lauersen JB, Bertelsen DM, & Andersen LB (2013). The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials. British journal of sports medicine PMID: 24100287