There is nothing I love more than diving into the scientific research with a burning question. Today’s Research Rundown, in an effort to keep us all swimrunning for a nice long time, is focused on how to prevent running injuries. Bad news first: running related injuries are insanely common. The good news: there is some low hanging fruit to be harvested that can significantly reduce your injury risk. The other news: this body of research is DEEP and truly cannot be summarized in a single article. Consider this the first part in a series of articles on running injury prevention, in which I try to keep things as simple as possible. Stay tuned for future deep-dives into some of the topics introduced in this Research Rundown.
Overload, overuse, and resiliency
Q: What’s the difference between a runner and an injured runner?
A: One year.
SAD BUT TRUE. The likelihood of injury within a one year training period is 27% for novice runners, 32% for recreational distance runners, and a whopping 52% for marathon runners. Yikes.
Next question… what is the most common cause of injury? 80% of running injuries are due to overuse. Overload is a well established training principle, but the wrong approach to overload can result in overuse. Let’s take a minute to define our terms. Overload in training stimulates performance adaptations: load must exceed capacity to improve performance. Gradually increasing variables impacting load (distance, pace, grade of terrain) will improve tolerance to future load. If the training load greatly exceeds the capacity of the tissues targeted by the activity (muscle, tendon, and bone) then overuse injuries may occur. Overuse injuries are common in activities requiring repetitive movements (one foot in front of the other for miles… running’s not repetitive at all!) without properly preparing the tissues of your body to withstand the stress of the activity.
So to prevent running injuries related to overuse we must employ two important tactics:
- Systematic and gradual increase of variables that impact load: distance, pace, and grade. Too much, too fast, too soon summarizes most training errors.
- Training within a spectrum of variety that increases resiliency and reduces the risk for too high a dose of the same repetitive loads to the legs.
- I know, I said two tactics, but the overuse equation also includes how we rest, recover, sleep, fuel, hydrate, manage stress, and more.
In a word, prevention of overuse injury boils down to resiliency. I think of resiliency as a buffer zone against those times when things don’t go as planned. Fatigue, poor fueling, unexpectedly challenging terrain, being chased by a bear and breaking into a full sprint… you get the idea. We need to be able to hold up to repetitive stress and unexpected variation. How do we train resiliency, while also putting in the necessary sport-specific work to specialize in swimrun? Resiliency can only be gained by exposing our bodies to a spectrum of variation within our run training. The more novel stimuli we can expose ourselves to in training the better chance we have at staying healthy, especially in swimrun where courses constantly serve up unexpected terrain challenges. Lucky for all of us, the unspoken mantra of swimrun is “expect the unexpected,” and so chances are your training will reflect a variety of conditions. That said, to prevent running injuries your workouts should vary pace, step-rate, distance, terrain, grade, footwear, intensity, and include non-running activities, such as strength training and coordination drills.
May the force be with you
Most running injuries occur at the knee or below, and this is consistent with what we know about how impact forces are distributed through the body during running. Loading is highest at the foot and ankle, and decreases as force is distributed up the kinetic chain. The forces absorbed by our joints when running can range from 1.5x to more than 8x bodyweight. Running injuries occur when our bones and muscles are not prepared to manage those forces. Below is a breakdown of the loads on each muscle group when running, courtesy of Rich Willy at Montana Running Lab.
Peak impact forces of running are greatest at the foot, ankle, calf, and knee. This is consistent with the location of the 5 most prevalent running injuries:
- Medial tibial stress syndrome (shin splints)
- Achilles tendinopathy (formerly know as tendinitis)
- Plantar fasciopathy (formerly know as fascitis)
- Patellar tendinopathy
- Ankle sprain
Injury Prediction: A multifactorial and non-linear model
What ultimately puts one runner more at risk than another for injury? We’ve already discussed improper progression of training load- this is probably the most significant and the most modifiable injury risk factor out there. But what else does the research say? A review analyzing biomechanical factors, training frequency, training volume, sex, and medical history came up with the following conclusion: The main risk factor for a running related injury is history of injury within the last 12 months. So how to prevent running injuries? DON’T GET INJURED. JUST DON’T. NOT EVEN ONCE. Simple.
Perhaps the reason it’s so difficult to nail down definitive risk factors for running injuries is due to the fact that running health is about more than just how we run. Let’s take a moment to appreciate that injury prediction is as much art as it is science. This is an area in the research where even the most left brained, statistically-oriented scientist writes with colorful prose. And now for the poetry:
“[injury prediction is] a complex interaction of a web of determinants” (Bittencourt et al., 2016)
“We are struck at the similarity between prediction of injury and predicting wildly complex events such as the path of hurricanes” (Stern et al., 2017)
Rather than initiating an injury prevention program with specific exercise interventions and training protocols, let’s begin with the basics. (Don’t worry, we will address protocols and exercise interventions in future posts!) Even the best training program design will result in injury if the athlete doesn’t recognize themselves as a dynamic and constantly changing system. This system- YOU- are either training in a “healthy state” or an “injury state.” Which state you’re in depends on the balance of many factors including coping skills, load, strength, fear, self efficacy, and movement strategies. When we are training at the edge, these factors must stay in balance to keep us on the healthy side of the mountain. This is summarized well in the schematic below.
RED FLAG SCENARIO
Ongoing self assessment and management of ALL the factors impacting training and injury risk is the best way to deal with your own dynamic system, or rather, your own hurricane prediction process as it may be. This can be as simple as logging sleep hours and quality, adjusting your nutrition, managing stress levels, and assessing other metrics such as resting heart rate, physical performance testing, or bloodwork. When you begin to notice changes in the system such as fatigue, high resting heart rate, or pain- take it as a warning sign. You can either be swept away by the hurricane, or you can BE the hurricane. Get to know your own personal weather system, and learn how to keep it in balance.
How to prevent running injuries- harvest the low hanging fruit
We’ve talked about load, overload, overuse, resiliency, the art and science of injury risk factors and prediction, and hurricanes. But the question remains: where does the rubber meet the road on all of this conceptual mumbo jumbo? How do we prevent running injuries? In honor of the new year, we’ve put together some action steps that directly address the concepts introduced in this Research Rundown. If your new years resolution is to prevent running injuries, here are our top 3 recommendations to balance training load, train resiliency, and keep your own dynamic weather system in balance.
1. Alternate between at least two different running shoe models during your training. This goes back to developing resiliency through exposure to novel stimuli. Changing up your shoes on a regular basis has been shown to reduce injury risk by 39%. That is no small potatoes, and a great excuse for a new pair of running shoes.
2. Get 8 hours of sleep a night. Sleep is one of the most significant non-running factors you can address to keep your system in a healthy state. Sleeping 8 hours has been shown to reduce injury risk by 61%! That’s legit big potatoes!
3. Incorporate strength training. Remember that the peak impact forces associated with running can be 1.5x to 8x bodyweight. Strength training is a way of safely increasing load to the muscles and joints (thereby increasing capacity) within a spectrum of variety, ie. in a way other than running. Strength training has been shown to reduce overuse injuries by 50%.
Want more details on how to prevent running injuries?
Check out our injury prevention videos and stay tuned for future posts on strength training for swimrunners, sleep hygiene, and more.
Disclaimer: The material presented on the Swimrun Labs website is for educational and informational purposes only, and should not be used to replace the diagnosis or treatment provided by a healthcare professional. Please consult a qualified healthcare professional if you are experiencing pain during exercise.
- Bittencourt NFN, Meeuwisse WH, Mendonça LD, Nettel-Aguirre A, Ocarino JM, Fonseca ST. Complex systems approach for sports injuries: moving from risk factor identification to injury pattern recognition—narrative review and new concept. British Journal of Sports Medicine. 2016;50(21):1309-1314. doi:10.1136/bjsports-2015-095850.
- Lauersen JB, Bertelsen DM, Andersen LB. The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials. British Journal of Sports Medicine. 2013;48(11):871-877. doi:10.1136/bjsports-2013-092538.
- Lopes AD, Hespanhol LC, Yeung SS, Costa LOP. What are the Main Running-Related Musculoskeletal Injuries? Sports Medicine. 2012;42(10):891-905. doi:10.1007/bf03262301.
- Malisoux L, Ramesh J, Mann R, Seil R, Urhausen A, Theisen D. Can parallel use of different running shoes decrease running-related injury risk? Scandinavian Journal of Medicine & Science in Sports.
- Rosen PV, Frohm A, Kottorp A, Fridén C, Heijne A. Too little sleep and an unhealthy diet could increase the risk of sustaining a new injury in adolescent elite athletes. Scandinavian Journal of Medicine & Science in Sports. 2016;27(11):1364-1371. doi:10.1111/sms.12735.
- Saragiotto BT, Yamato TP, Junior LCH, Rainbow MJ, Davis IS, Lopes AD. What are the Main Risk Factors for Running-Related Injuries? Sports Medicine. 2014;44(8):1153-1163. doi:10.1007/s40279-014-0194-6.
- Stern BD, Hegedus EJ, Lai Y-C. Injury prediction as a non-linear system. Physical Therapy in Sport. 2020;41:43-48. doi:10.1016/j.ptsp.2019.10.010. 2013;25(1):110-115. doi:10.1111/sms.12154.