By Max Prokopy
Running is one of our most popular and organic activities. Throughout human history it helped us hunt, communicate, compete, and reduce disease. Unfortunately, modern runners experience many injuries. Each calendar year, approximately 65-80% of runners report an injury that forces them to stop for at least a week. According to Running Medicine by Dr. Robert Wilder, the rate increases sharply as one approaches 20 miles per week. About 90% of running injuries are over-use, meaning rest helps but the problem is likely to recur. This article will examine several injury-prevention strategies and the latest equipment controversy, barefoot running.
During previous graduate work I was lucky enough to intern at The University of Virginia’s SPEED Clinic, one of the nation’s most advanced biomechanics laboratories. I’ve distilled that experience into some tips that can help keep you on the road. The simplest way to improve running mechanics is to optimize your cadence, aka foot strikes per minute. In essence, the less time your foot spends on the ground, the less can go wrong. Timing your cadence is easy:
1) run at your typical pace;
2) count the number of times your right foot touches the ground in 30 seconds; and
3) multiply that number by 2 to calculate foot strikes per minute.
Optimal cadence is 90-95 strikes per foot, whether you run a 5-minute mile or a 10-minute mile.
Here are some quick tips to up cadence and reduce overuse. More detailed explanations follow.
- Run at higher intensity with walking rest. Repeat cycles of 30 sec. hard running, 60 sec. walking.
- Run on trails, grass, or other constantly changing surfaces.
- Lean slightly forward from the ankles, chest out.
- Run smoothly and quietly. Take a break when those two qualities disappear.
- Run with as little foot cushion as possible. Approach minimalism cautiously, details below.
How’s My Form?
Some people insist a mid-foot/forefoot strike is the only acceptable way to run. While not universally true, heel striking does tend to decrease cadence (bad). It’s often helpful to have a friend take video of you running on a treadmill. Capture viewpoints from the side and from behind. Here’s a list of things to look out for which will determine cadence, compensation, and joint stresses:
|Generally Good||Generally Bad|
|Little to no vertical motion||Bobbing up and down|
|Feet strike underneath the hips||Feet strike out ahead of the body|
|Slight forward lean with the chest out||Upright torso with the head down|
|Quiet foot strikes||Loud pounding sounds|
The table’s attributes tend to cluster so fixing one problem tends to fix the others, as well. Luckily, increasing cadence tends to help all of them at once.
The Biggest Little Muscles
Another common cause of injury is instability in the hips and feet. In very general terms, the foot and hip rotator muscles play crucial roles. People often try to improve stability by strengthening the hip rotators, for example in the clamshell exercise. Although a good exercise, these little muscles (see figure) will never get stronger than the primary muscles of the thighs. Timing is the key to joint stabilization and healthy running. These three videos provide good examples of how to improve stability of the hip, knee, and ankle: the band squat, RFE squat and split squat. The bottom line is to not let the inward pull of the resistance collapse your knee. This is called reflex stabilization and provides huge returns on your time investment.
The foot muscles have rightly received an increasing amount of attention. A stable arch is critical because that’s the only thing supporting your entire bodyweight. Note: there are people whose skeleton does not allow them to make an arch. Although a small minority, their needs extend beyond the scope of this article. The picture below shows how you test to see if your foot is able to make an arch.
Most people with “flat feet” have simply lost the foot strength to maintain that arch while supporting their bodyweight. In this video, Arizona-based expert Patrick Ward offers superb advice and practical tips on re-training the foot. The video’s row exercise is but one choice of many. The point is to establish an arch and maintain it while completing another task.
Less is More?
Much has been made of the recent minimalist movement, where high-tech running shoes are eschewed in favor of sandals, FiveFingers, or plain bare feet.
The basic physics favor the minimalists. It’s well documented that the legendary Kenyan runners don’t wear shoes for most, if not all, of their development. The same holds true for other successful running cultures. The simplified picture (below, left) shows how the arch works better when force is on top of it. Imagine a super cushy arch support pushing up on the keystone. That would de-stabilize the relationship between the weight-bearing stones. The arch would less reliably hold the weight resting upon it.
There are a few people who have a structural need for orthotics (e.g., severe bunions). However, the modern cushioned inserts impair the foot’s ability to receive feedback from the ground and send it to the brain. The brain devotes about equal amounts of capacity to the feet as the hands. If you try typing with gloves on, the point about cushioning becomes pretty clear. If the feet can’t feel what’s going on, the hips and core will not do their jobs.
Approach re-training your feet with caution. World-famous therapist Gray Cook recommends beginning with 2-5 minutes of light running, skips or jumping rope. Slowly increase duration and intensity; think about adding 10% per week. Walk around the house barefoot, too.
Many runners swear that asphalt hurts their knees. The physical truth is that impact itself is a relatively small force. The highest joint stress occurs when your body is on top of the grounded foot. A constant surface, especially a crowned road, insults the body with the same set of stresses for every stride. Adding up 1500 foot strikes per mile of the same forces is the textbook definition of overuse. An uneven and changing surface from trails or grass allows the body to distribute stress over a much greater range of positions. In short, trail or grass running is probably better and more fun.
Run Harder for a Shorter Time
I’ve touched on cadence several times because it’s a simple way to evaluate your efficiency. Make no mistake, good efficiency is injury reduction. Trying to think about every joint position is both fruitless and stressful. Sprint-walks are a terrific way to improve cadence, reduce total mileage, and still get in a terrific run. Run hard for 15-60 seconds, walk for about double that time, and repeat. As above, start with short durations and add about 10% per week. Intense running almost always invites better mechanics and there’s time to socialize if you wish. This treadmill video shows how a perfectly fine runner bobs up and down due to slow cadence. This sprint video shows equally capable people. However, the increased intensity actually improves vertical bob, cadence, and foot position. There’s no need to simulate a track start, just run harder for less time and walk or skip for rest.
Max Prokopy is a first-year Biochemical and Molecular Nutrition PhD student who has certifications and experience with training prep, collegiate and professional athletes with a particular focus on ice hockey.