Since the release of Dr. Lieberman’s study I’ve had a few requests from folks wanting me to show my test results from a gait analysis I had done at the UVA human performance lab. They’re curious to see how my Ground Reaction Force (GFR) chart compares with the one shown in the Nature video showing a barefoot runner (I’m assuming Lieberman himself) landing on a strike plate with a GFR chart beneath.

In the tests I did at UVA, I was wearing three different pairs of shoes (I was never tested barefoot): tai chi shoes, NB-MF800’s and NB-790’s. I’ve pasted in three graphs below. The first two are of a barefoot runner running with a heel strike, a barefoot runner running with a forefoot landing and the third graph is of me with the graphs of all three of my tests overlaid onto the same chart in three different colors.

GRF for a Heel Striker

GRF for a Forefoot Striker

GRF for Danny

Notice the differences in GFR between the three runners shown as a multiple of Body Weight measured during the initial weight-bearing phase. The Barefoot runner had a multiple of 1.85 x Body Weight. To make the comparisons fair, let’s assume all three tests were done with a runner who weights 150 lbs., that would mean (with a GFR of 1.85 x Body weight) that his heels were absorbing a force of 277.5 lbs. upon impact. Let’s say that his heel has an area of 5 sq. inches. that would mean that his heels were experiencing an impact of about 55.5 lbs./sq. inch. Ouch!!!

In the second figure, the runner is landing on his forefoot and his GFR is 2.64 x Body Weight during his support phase which figures out to 2.64 x 150 lbs. = 396 lbs. Now let’s say that the area of his forefoot is approximately 16 sq. inches. That would mean that his foot would be absorbing about 24.75 lbs./sq. inch. … or less than half of what the heel striker feels.

In the third figure I’m landing in a midfoot (or fullfoot) strike which means that the entire bottom of my foot is landing as my foot hits the ground. My GFR was measured at 2.47 x Body Weight or 2.47 x 150 lbs. = 370.5 lbs. Now, if the surface area of the entire bottom of my foot is roughly 30 sq. inches. (I’m a size 9.5 shoe), that would mean that the impact felt by my feet would be approximately 12.35 lbs./sq. inch. or half as much as the forefoot striker. That’s less than 25% of the impact per square inch the heel striker feels and half of what the forefoot striker feels. You can also see that my GFR was the same no matter which shoes I was wearing. I imagine that it would still have been the same had I been tested barefoot… possibly implying that there’s something to be said for working on improving your running technique. It’s about the runner, not the shoe.

I’ve used 150 lbs. as a standard weight for all three runners because I don’t know how much Dr. Leiberman weights. I also used the size of my feet in my calculations because I also don’t know his shoe size. BUT, the point I’m trying to make here is that whether or not you run with shoes on, your impact with the ground will be most if you land in a heel strike because there’s a lot of force going into a relatively small area of your foot. Subsequently, if you land in a forefoot strike, you land with more area of your foot touching the ground and it spreads the force of impact over a larger area thereby reducing the amount of impact per square inch. And lastly, if you land in a fullfoot strike, you spread the impact out over a much larger area and lower your impact per square inch even more still.

Since greater impact with the ground can most likely be directly related to greater incidence of impact injuries, this all boils down to one big question. How do you lower your impact with the ground so that you don’t hurt yourself when you’re running. My premise is that although some types of shoes can reduce shock and impact, it’s the runner who, in the end, is responsible for learning how to manage his or her impact with the ground in a way that consistently works. This is the need that is presented to every runner and it is one of the main reasons why ChiRunning was developed.

Dr. Liebermans study was a good beginning into seeing the difference in impact forces between shod and barefoot runners. Next, I would like to see a study comparing the difference in impact between heel strikers, midfoot strikers and forefoot strikers; with bare feet, with minimal shoes, racing flats, and with your basic high-heeled running shoes.

There are times to run with a forefoot strike. There are times to run with a fullfoot strike. And, there are times to run (believe it or not) with a heel strike. I’ll cover these in a future blog.

Run well…be well,
Danny

There seems to be much debate in the running community today on what is the best footstrike for running. Runners of all levels divide themselves into three basic camps: the midfoot strikers, the forefoot strikers and the heel strikers. So, here is my attempt to put forward my best understanding of the three basic types of foot strike and what each one does for a runner.

The Midfoot Strike
The midfoot strike is characterized as having your heel and the ball of your foot touching the ground simultaneously with each foot strike. You can see this very clearly when you watch young children run. They always land with their whole foot on the ground. I would say that at least 95% of all people run this way as kids.

In the ChiRunning technique, we promote the midfoot strike because it is, for most runners, the most injury-preventive way to run. Our emphasis is on preventing the lower legs (including the knees) from over-working, because this area of the body is where, conservatively speaking, 90% of all running injuries occur. Plantar fasciitis, achilles tendonitis, shin splints, calf pulls, knee pain, IT band problems, over-pronation, bunions, metatarsal and tibial stress fractures, and hammer toes lead the list of the most common running injuries. This list is immense compared to everything that can go wrong above the knees.

The propulsion in ChiRunning comes from allowing your body to fall forward with the pull of gravity, not from pushing yourself forward with your feet and legs. For this reason it is more energy-efficient because your legs are not required for propulsion. When your feet come down onto the ground, they land either under or slightly behind your center of mass, in a midfoot strike. The only work required of your legs is to provide momentary support for your body between strides. Landing on your midfoot, in most cases, either reduces or eliminates the work done by A.) the lower leg muscles…especially the shins and calves, and B.) the two tendons that are most commonly injured… the plantar tendon and the achilles tendon.

The ChiRunning technique is primarily focused on energy efficiency and injury-prevention with speed being a secondary focus.

The Forefoot Strike
The forefoot is basically the part of the foot between the forward-most part of the arch and the end of the toes… generally speaking, the balls of the feet. If your heels don’t touch the ground when you run, you’re a forefoot striker.

Sprinters, middle-distance runners, and some triathletes tend to prefer running on the forefoot because of the extra speed obtained by “paw-back” and “toeing off.” This way of running is great if you want lots of speed, but it puts the responsibility for most of the body’s propulsion squarely onto the legs…especially the lower legs. Some of the faster elite middle-distance runners (i.e. Kenyans, Moroccans, Ethiopians, Mexicans) run with a forward lean added in combination with a forefoot strike. This takes some but not all of the burden off the lower legs.

Because forefoot running is primarily used for running at faster speeds, energy efficiency tends to take a distant back seat. As far as being injury-preventive, forefoot striking helps prevent knee injuries because it lowers the impact to the knees. This is a good thing. But the problem with it is that running on the balls of your feet increases the workload on your calves, shins, achilles tendons, and plantar tendons, so you risk either overworking a muscle or pulling a tendon if you go too far or too fast while running on your forefeet.

The Heel Strike
Heel striking is when your heel strikes the ground in front of your body. At least 75% of all runners run with a heel strike. The interesting thing about this fact is that, although it is by far the most common of all the footstrike patterns, it is not done by choice, but by default. The vast majority of all runners are not elite runners or competitors, they’re just regular folks like you and me, who like to run and like to stay fit.

Most recreational runners tend to run with their body in an upright position… with no lean at all. This forces them to have to reach forward with their legs when they run…and when you run upright and reach with your legs, your feet will always land in front of your body and your heels will come down first. When you run this way, you’re basically putting on the brakes with each stride, which sends a lot of impact to your lower legs and knees. For this reason, many heel strikers complain of knee pain at some point in their running career. This is the group that keeps orthopedists and physical therapists in business.

But, just because you might be a heel striker, it doesn’t mean you’re doomed to be a heel striker for the rest of your life. Work on improving your running technique. If you can learn to run safely and efficiently, you’ll be eliminating the causes of running injuries and you won’t have to worry about ending up in a doctor’s office getting fixed.

The midfoot strike works for most runners…the forefoot strike works for some runners…but, the heel strike doesn’t seem to work well for anybody. Try all three and see which one works the best for you.

With the ChiRunning book, DVD or audio CD you can easily learn the midfoot strike. We offer you an alternative way to approach your running so that you can learn the midfoot strike and spend many more years enjoying one of the world’s best and most natural sports.

Happy trails,

Danny