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."

How to fuel before the big race

Special thanks to Brian Joyce, ProRehab physical therapist and our very own half-marathoner for the great article on pre-race nutrition! Enjoy!


Fueling prior to a half or full marathon:

Research shows that in order to keep the liver full of glycogen stores and maximize your energy level throughout the duration of longer races, it’s best to consume 1.5-1.8 grams of carbohydrates per pound of body weight. For a 150-lb runner, that equates to at least 900 calories to consume prior to your race! The American College of Sports Medicine recommends eating this meal 3-4 hours prior to your race. Since most races start between 7 to 8 am, it may be unrealistic to wake up so early to eat this meal. In this case, try consuming 1 gram of carbohydrates per pound of bodyweight 2 hours before the race. Since this will not be the optimal amount of carbohydrates for a longer race, you will want to fuel early in the race with energy gels and continue with a consuming 30-60 grams of carbohydrates each hour during the race. Regardless of which strategy you choose, the safest way to avoid any GI issues during the race is to practice following this nutritional guideline prior to a workout so you know you can handle this amount of calories prior to a hard effort.

Taken from Runner’s World:

Sample pre-race meal plan for a 150 lb. runner:


3 to 4 hours prerace
1 cup cooked oatmeal with 2 tablespoons honey 62 g of carbs
6 ounces yogurt 17 g
1 large banana 31 g
2 tablespoons raisins 16 g
4 ounces juice 14 g
12 to 20 ounces water 0 g
Total Carbs = 140 g



90 minutes to 2 hours prerace
1 slice bread with 1 tablespoon jam 28 g
24 ounces sports drink 47 g
Total Carbs = 75 g



30 to 60 minutes prerace
1 energy gel or serving of energy chews 25 g
8 to 12 ounces water 0 g
Total Carbs = 25 g


Other pre-race nutrition tips:

1. Avoid new foods – The most important thing prior to a big race is to not try anything new that your body may not respond well to, and this includes nutrition as well. Often, bigger races are in new cities and you may be enticed to try a new restaurant prior to the next morning’s race, but this may not be in the best interest of your digestive system. Stick to simple and familiar foods that you know your body can handle. Avoid excessive fiber, spicy foods, and high fat foods. These may give you gas if your body is not accustomed to this diet.


2. Obtain more of your carbohydrates from fruits and vegetables – Although carbohydrate loading makes people think it’s beneficial to stuff oneself with pastas and breads, this may not be the best option to try the day before a race (especially a race shorter than a half marathon). Instead, try a moderate amount of carbohydrates in the several days prior to the race. The fruit and vegetable sources will provide the needed carbohydrates as well as added nutrients. Grain sources are fine to consume as well, but try just eating to fullness rather than engorging yourself with breadsticks, pasta, or pizza.


3. Eat breakfast the morning of the race – although pre-race jitters may leave your stomach mildly upset and in no mood for filling itself with anything sloshing around every step of the race, breakfast can fill you with an energy source to tap into during the race rather than leave you feeling full and sending you on an extra trip to the porta-potty. Studies show that breakfast keeps your blood sugar steady and can leave you less likely to bonk during a race. So don’t miss the opportunity to provide yourself with a more steady energy source the morning of the race. If solid foods are unreasonable for you to eat pre-race, try liquid sources such as a fruit smoothie, juice, or yogurt (as long as these are familiar foods to you).


4. Limit excessive water consumption – While water is essential optimal race performance and even 2% in body weight loss due to dehydration can lead to a decline in performance, be careful diluting your electrolytes pre-race by chugging water alone. Low electrolyte levels can lead to cramping and in extreme cases, hyponatremia, a potentially life-threatening condition of depleted sodium levels. A good recommendation would be to drink 16 ounces about 2-3 hours prior to the race and another cup of water just before toeing the line.

Exercise and Pregnancy

Kate Schwartzkopf-Phifer, doctor of physical therapy, discusses the benefits of exercising while pregnant. Kate works at the ProRehab on Indiana Street and is an avid runner and triathlete. As with any pregnancy, it is important to discuss exercising with your physician and obtain approval first. Kate provides some general guidelines regarding exercise and the benefits both during and after pregnancy.

Enjoy! 

Now that you’re pregnant, you’re probably feeling like it’s a good time to kick your feet up and relax. After all, you’re more tired than you’ve ever been, and your “morning sickness” has turned into “all day sickness”. You deserve a break, right? Well, yes and no.

While getting adequate rest is definitely recommended, if you have an uncomplicated pregnancy, a respite from exercise is not. The American College of Sports Medicine and the Centers for Disease Control and Prevention currently recommend 30 minutes of moderate intensity exercise on most, if not all, days of the week. Recreational activities are deemed appropriate based on the physical movements required for the sport. Those activities that put the individual at high risk of falling or high risk of abdominal contact should be avoided. Such activities include skiing, horseback riding, hockey, soccer and basketball. Scuba diving should also be avoided due to the risk for decompression sickness and exercising at high altitudes should be cautioned due the risk of altitude sickness. Exercises that require you to be in a supine (lying on your back) position are considered unsafe after the first trimester, as this position tends to decrease venous return. Safe, moderate intensity activities include brisk walking, aquatic aerobics or swimming, stationary biking and even push-mowing your lawn. Women who participated in more vigorous intensity exercise pre-pregnancy, such as running, can likely continue these activities. However, these high intensity exercises should be monitored closely by a physician.

Aside from helping to prevent excess weight gain, there are plenty of benefits to maintaining a safe fitness routine while pregnant. Regular exercise can actually give you more energy, even though that sounds contradictory. Shouldn’t exercise make you tired? If you exercise at the recommended intensity for 30 minutes daily, it actually gives your system a boost of energy, while also helping you to sleep more soundly at night. Many women also report difficulty with constipation while pregnant; yet another ailment exercise can improve. Active bodies promote active bowels, so even a short walk can help alleviate the discomfort of bloating and constipation. Active, fit mommy’s-to-be also tend to tolerate labor better, and recover faster. Lastly, staying in shape during your pregnancy also helps to return you to your previous shape sooner, and say good-bye to those fashionable stretchy waistbands.

The benefits of a regular exercise routine are not just limited to the mom-to-be. Babies of mom’s who exercised during pregnancy tend to be of healthier weight, and maintain a healthy weight throughout their lifetime. There is also some evidence that suggests babies of exercising mom’s slept through the night sooner than those born to non-exercisers. That alone can be reason enough to put on your walking shoes.

Not a regular exerciser before you were pregnant? No problem. As long as you have the OK from your physician, you can start with just a 5 minute walk every day. Gradually work your way up to 30 minutes over a period of several weeks, listening to your body along the way. Don’t ignore any aches or pains, whether in your mid-section or otherwise. Make sure to stay hydrated, and maintain healthy nutritional intake (which increases after the first trimester).

Of course there are going to be days where you are too tired to even put on your tennis shoes, let alone walk around the block. That’s okay! Take the day off, and get back at it tomorrow. Remember, it’s not too early to introduce your little one to the benefits of a healthy lifestyle!

Toe Touch Progression

Can you touch your toes? Most people would say no, even seasoned athletes. Tight hamstrings? Probably not the sole culprit. Muscle tone and your body's misuse of stability? Sounds more likely. Give your body credit though, it's pretty good at taking the easy way out and choosing the simpler option. If your core lacks the ability to stabilize your pelvis, the hamstrings take over and create it. This might make your hamstrings feel "tight" but in actuality, they are working non-stop and always "on" so to speak. Try this exercise demonstrated by Paul Gorman from The Tank Gym. If you are able to do the toe touch progression and see a noticeable difference in your ability to reach your toes, you are NOT dealing with a muscle tightness issue; it's muscle tone. Perform this exercise daily to "turn off" your hamstrings and allow your core to be more efficient while stabilizing your pelvis.

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. 

Part 3: Urinary Incontinence

To conclude Lisa's 3 part series on urinary incontinence, we have put together a video! She discusses what conditions we treat and the methods of treatment.

Pelvic Floor Video

Enjoy!

Part 2: America's Best Kept Secret...Urinary Incontinence

Last week Lisa Kiesel, physical therapist at ProRehab, wrote a great article on Urinary Incontinence. You can reference her first article below. Today, she is talking about what foods are good and what foods you should avoid for optimal bladder health. Enjoy!



Bladder habits are also very important to consider. Certain foods and drinks can be irritating to the bladder and cause you to urinate more often. Some examples of these are spicy and citrus foods, tea, coffee and soda (caffeinated and decaffeinated), foods and drinks with artificial flavoring, coloring and sweeteners, alcoholic beverages, milk products and chocolate. You may say “What CAN I eat?” The key is a balance between these irritating foods and drinks and plenty of water. One common mistake people make with bladder control issues is to limit their fluids. This causes the urine to be more concentrated and irritates the bladder which causes an increase in frequency. If you wake up a lot at night to urinate, drink most of your fluids during the day and limit what you drink after dinner, making sure most of it is water.

Some foods that promote bladder health include fresh fruits and vegetables, whole grains, foods high in Omega-3 fatty acids and water. Fruits and vegetables high in vitamin C, E, magnesium, potassium and fiber include carrots, sweet potatoes, strawberries, blackberries, cranberries, blueberries, mustard greens, turnips and cabbage. Whole grains such as rye, wild and brown rice, barley, brown pasta, oatmeal and whole grain breads promote liquid and solid waste removal from your body and promote a healthy bladder and colon. Foods high in Omega-3 fatty acids such as nuts (Brazil nuts, almonds, peanuts, macadamia nuts) and fish (trout, salmon, mackerel, tuna, herring, halibut, sardines) are helpful to reduce inflammation to enhance bladder health. Water is also very important because it flushes harmful toxins and bacteria out of the bladder and urethra.

You don’t have to live with it…remember that 80% of incontinence cases can be improved by a combination of behavioral changes and pelvic floor exercises when done correctly. Talk to your health care provider today and see if you can improve your symptoms.


Lisa Kiesel, PT, DPT, BCB-PMD

ProRehab, PC

812-476-0409

lisa@prorehab-pc.com

www.prorehab-pc.com




National Kidney and Urologic Diseases Information Clearinghouse

1-800-891-5390

www.kidney.niddk.nih.gov




National Association for Continence (NAFC)

1-800-BLADDER (252-3337)

www.nafc.org