Does a minimalist shoe decrease impact forces?

Below is an article published in Runner's World. There has been a lot of recent talk about how minimalist shoes decrease ground reaction forces, but a recent study looking at the Nike Pegasus vs Nike Free, found the opposite.

Study: Impact Forces Greater in Nike Free than in Pegasus

Researchers surprised by their findings.

By

Scott Douglas

Published

July 26, 2013

One of the main criticisms of conventional running shoes raised over the last few years has been that they encourage "hard" landings that increase the impact forces of running, especially on initial contact with the ground.Minimalist shoes, some advocates say, can help reduce impact forces, in part by encouraging a "softer" foot strike and more of a midfoot landing.

A new study by two well-known researchers suggests that, as is often the case in matters of shoes, form, and injury, things aren't that simple.

Richard Willy, Ph.D., of Ohio University, and Irene Davis, Ph.D., of Harvard Medical School, had 14 men run on a treadmill for 10 minutes at a time, at 8:00/mile pace. The men were all rearfoot strikers who were accustomed only to conventional running shoes.

For one of the 10-minute runs, the men wore the Nike Pegasus, which the researchers classified as a standard running shoe. On another 10-minute run, the men wore the Nike Free 3.0, which the researchers classified as a minimalist running shoe. According to the researchers' measurements, the Pegasus' heel height was 36.3 millimeters, compared to 17.6 millimeters for the Free. On the basis of compression tests, the Pegasus provided 31% more cushioning, the researchers said.

While the men ran, Willy and Davis recorded impact forces, stride length and other biomechanical data. They took measurements at the 1-minute mark of the run, and again at the 10-minute mark, to see if impact forces, joint angles, etc. changed during the short run.

The results were the opposite of what Willy and Davis had expected. As they wrote, when in the Free "runners struck the ground with a more dorsiflexed foot [toes pointing toward the shin, meaning more of a heel strike], in more knee flexion, and with higher vertical impact peak and higher average vertical loading rate."

These differences remained consistent throughout the run. That is, as the men--who, again, weren't used to running in a shoe like the Free--continued to run in the Free, they didn't adjust their form to compensate for being in the Free. Their stride length and stride rate remained comparable to when they ran in the Pegasus, and their impact forces remained greater than in the Pegasus.

"Absolutely," Willy wrote in an email when asked by Runner's World Newswireif his findings surprised him.

"We expected that impacts would initially be higher in the minimalist shoe than the standard shoe in the first minute of running. After 10 minutes of running, we expected the reduced cushioning of the minimalist shoe would cause heel discomfort, resulting in a less inclined foot at foot strike, perhaps even a midfoot strike pattern. We then expected a likewise reduction in impact forces. Obviously, our results were completely counter to what we hypothesized."

Willy said that he and Davis used the Free instead of a more barefoot-style shoe, such as the Vibram Fivefingers, because of the popularity of the Free and its positioning as a transitional shoe for runners looking to switch from conventional trainers to barefoot-style running.

"These shoes are widely marketed to the general running public to closely mimic a barefoot running experience to gain many of the benefits of barefoot running, i.e., reduced impact forces, without the increased risk of foot injury due to road debris," Willy wrote. "Due to the popularity of this shoe type and industry claims, we felt that it would be an interesting study.

"Another major reason why we wanted to study this type of shoe is that clinicians often prescribe this type of shoe to patients who are recovering from an impact-related injury to encourage a reduction in impact forces during running. Our findings suggest that this practice may not be advisable, at least in the short term."

It's important to keep in mind that the runners in this study were unused to minimalist shoes. It's possible that, over time, they might have altered their form in the Frees to lessen the increased impact forces Willy and Davis measured.

To Willy, that fact provides another important take-away from his research.

"Our subjects were novel minimalist shoe runners and they did not receive any instruction on running mechanics," Willy told Newswire. "In order to see a change in running mechanics, a structured training program focusing on changing a component of gait may likely be needed.

"For instance, increasing step rate during running has been shown to reduce ground reaction forces," Willy wrote. "Therefore, runners who wish to transition to minimalism should consider that a thoughtful and directed gait retraining program may be necessary to mimic barefoot running, regardless of the shoe worn."

The Truth About Barefoot Running: It's not for everyone!

Barefoot running is on an upward trend across the country, however those new to it should beware because it is not for everyone! Before making the transition, an athlete should make an informed decision by understanding the pros and cons of unshod running/walking.

Bob Tank, Doctor of Physical Therapy and orthotic specialist at ProRehab, PC discusses both the facts and his opinions of barefoot running.


The arguments for barefoot running are that it is more efficient energy wise and that it leads to fewer injuries.

I do not believe either of these statements have been scientifically proven and in fact, it can be argued that it may be less efficient since the energy absorbed in barefoot running is an additional load to the calf muscles. In regards to less injury risk, the premise is that barefoot running results in landing more on the forefoot or midfoot as opposed to having the impact at the rearfoot or heel. Heel striking generally results from a longer stride (step length) and results in the foot landing more out in front of the body. This is thought to then result in the body having to exert a “braking” force to maintain our balance and this force is then transferred and ultimately absorbed up to the knees and hips. If in barefoot running the foot lands more on the front part of the foot, it is argued that the foot placement will be more directly under the body (knees) and therefore the impact will be decreased and absorbed by the muscles more than the bones and joints. None of this has been conclusively proven. One of the drawbacks to barefoot running is this can shift the impact stresses to areas that are not accustomed to those types of loads and therefore may result in increased injuries to the Achilles Tendons, Plantar fascia (arch strut) and metatarsals. Because of this, if a runner chooses to change their running style to involve barefoot running, they need slowly transition to this over an extended period of time (months). Greater tension is placed upon the Achilles tendon and arch structures in unshod running simply due to the fact that running shoes keep the heels from dropping down to the normal 12mm heel lift built into the midsole of a running shoe. Minimalist shoes are somewhat of a compromise as they have 0-5mm heel lifts built in (depending on the model) and allow the runner to more comfortably land on their forefoot. They are also more flexible, lighter weight, and have more cushioning that the standard running shoe but, this results in less control over excessive movement or rolling of the foot. They also wear out quicker due to the less durable materials used in manufacturing them.

My opinion is that if a runner is considering transitioning to barefoot running, that they first try to shorten their stride in their regular shoes, which should alter the landing point to more toward the forefoot (away from the heel). They can practice this on a treadmill first with emphasis on quicker turnover, at a set speed, and they should focus on running tall, landing soft and with less noise at impact.

It should be mentioned that foot strike position at initial impact is not solely related to type or absence of shoes but is also related to fatigue, speed, joint flexibility, previous injuries and body structure. Those runners with a foot type that is either extremely flat (pronated) or extremely high arched (supinated) should be especially cautious about trying to run barefoot. In my experience, these runners would decrease their chance of injuries by wearing a shoe designed for their excessive pronation movement (more stability built into the shoe) or one designed for additional cushioning in the case of the high arched foot type. Further protection can be provided through the appropriate use of custom molded foot orthotics which are designed for total contact with the sole of the foot and built with a deep heel cup to not only help absorb impact forces but also to control excessive side to side rolling of the foot (side note, not all custom orthotics are built with these features included). This type of running orthotic is designed to accommodate for faulty foot or leg structure and cannot be used during barefoot running and is less effective in minimalist shoes. 

For clarification, in my mind I would classify minimalist shoes as Nike Frees, other light weight shoes with minimal structure but nonetheless they have a full outersole, just minimal heel lift built into the sole. The Vibram 5 toed shoes I would classify as more of a barefoot shoe. 

Help Run the World

This article comes from Competitor Magazine (running.competitor.com). The two men below created an apparel company that donate part of the clothing costs to countries in need of clean food and water. Read on to find out more, or you can visit their website at 

runjanji.com

Running Clothes For A Cause

• By Jeff Banowetz
• Published 5 hours ago

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Mike Burnstein and Dave Spandorfer, co-founders of Janji.

Two college cross-country teammates launch new apparel line to help runners aid countries in need. 

Dave Spandorfer and Mike Burnstein  ran cross-country and track together at Washington University in St. Louis. Now they’re working together to make a business focused on their love of running while promoting a cause near and dear to runners: clean water.

The two created Janji (the name means “promise” in Malay), a running apparel company that is dedicated to helping combat the food and water crises around the world. The company has created technical shorts and tops incorporating the flags of countries that have problems obtaining clean food and water. For each item purchased, approximately $4 is donated to that country to help solve the problem.

The company officially launches its line—starting with designs for Haiti and Kenya—at the Big River Running Company in St. Louis on May 3. It will continue introducing apparel at specialty running stores this summer and through their website, runjanji.com. Before the introduction, co-founder Spandorfer spoke with Competitor to give us some background on the company, its goals and the issue of clean drinking water that most runners take for granted.

When did you come up with the idea for Janji?

Mike and I came up with the idea for Janji on the way to the D3 National Outdoor Track Championship. We were sitting on the bus surrounded by our friends with the opportunity to compete against some of the best athletes in the country. We felt pretty lucky. It was at the time that we wanted to find a way to give back through our sport. We knew there were thousands of races for a cause and we thought, well, let’s try and find a way for runners to give back each and every time they run—beyond just race day. By the time the track meet ended, Janji was born.

What is your running background?

Mike and I have both been running since our freshman year in high school. My team was nothing special, while Mike’s team was a running powerhouse. We met at Washington University, where we ran cross-country and track. Together, we’ve had a lot of success in running with five school records and five All-American awards between the two of us. After college, Mike plans to run half and full marathons, as I have been doing.

Had you any experience in apparel before starting the company?

When we had the idea to start Janji, we had a passion to give back but limited experience with apparel manufacturing and retail. Since then, we’ve read extensively and have talked to many mentors, who have guided us. I’ve also spent the past year working part-time at a specialty running store, Big River Running Company, which taught me the ropes of the running apparel industry.

Tell us about the products you have available now. What materials are they made out of? Where are the manufactured?

Janji’s shirts and shorts are both made out of 100 percent polyester fabric. Although the feel of the fabrics are very different, they’re all moisture-wicking and incredibly light. We’re working with a producer, located in China, which has shown a commitment to fair wages, proper working conditions and ethical labor practices.

How long have you been involved in the global food and water crisis?

We felt there was a natural connection between runners and the food and water crisis. Who knows more about the importance of being well fed and well hydrated than runners? At the D3 National meet, Mike and I were very cautious of what we ate and drank as we approached our big races. Yet we knew that hundreds of millions of people worldwide don’t even have access to adequate nutrition and clean water. Since the minute we started the company, we wanted to change that. While we have minimal experience in international public health, we are committed to working with partnering organizations around the world dedicated to alleviating problems related to unsafe water conditions and food insecurity.

****

For more information, visit runjanji.com. The official launch at the Big River Running Company (West County location) takes place on Thursday, May 3, at 7 p.m. Find out more at bigriverrunning.com. On May 10, the Naperville Running Company in Naperville, Ill., will host a launch at 6 p.m. Visit runningcompany.comrunningcompany.com/Calendar/Events/Event-76 for details. 

The Compression Battle: Socks vs. Sleeves

Compressive garments are becoming popular in running and triathlete groups. Their purpose can be two fold: to keep muscles warm and improve blood flow to the lower legs, and to aid in recovery after a race or long bouts of training. So what is the difference between a compression sock and sleeve, and what is the right choice for you?

A compression sock is full length from the toe to knee. This is a good choice if you're a runner that isn't particular about wearing a certain style sock or if you don't wear a low profile minimalist shoe. The material around the foot can be a little thick and difficult to fit into a minimalist style shoe. A compression sleeve runs from the ankle to knee. When wearing a sleeve, you can wear your typical socks and shoes. If you're a trail runner this may be a better option as you could wear a moisture wicking sock as well as the sleeve. For a triathlete, the sleeve is also superior because it can be worn during the swim and makes for a faster first transition time.

If your intent is to wear the compression garment for recovery, then the full length sock is the better choice. The sleeve may cause some mild swelling in the feet when your body is a little more sedentary. This won't be the case wearing the full length sock because of the constant compression from toe to knee.

There are definitely pros and cons to both the sock and sleeve. It all comes down to personal preference and what your intended use will be. 

New Running Singlet

Ultimate Fit has introduced their 2012 running singlet. Samples are available to try on at the store (in order to gauge your size) until February 11, 2012. Orders will take 8-9 weeks. The singlets are a very high quality material and come in men's and women's sizes.  They look like the picture to the right except some additional sponsors will be added, including ProRehab! The price is $34.99/ea. Stop by the store to try one on and place your order today!

1308 S Green River Rd
Evansville, IN
812-431-0201

Shoe Review

We will now be featuring a weekly shoe review from Curt Jones, owner of Ultimate Fit, and shoe specialist! Check out the first one posted today!