Runners are an interesting breed. It’s obvious that the number one goal in most sports is to do something (to win, to get stronger, to pass more), but the top goal for many a runner is to not do something. That is, to not get injured. According to Tom Derderian, a former member and current coach of the Greater Boston Track Club, “If you talk to an elite or near-elite American distance runner today, they’ll tell you that the primary aim of their training is to avoid injury.” (John Brant, Duel in the Sun)

Running specialty stores offering a gait analysis to support the runner’s number one goal have grown in recent years. Like a medical doctor, these stores, along with online websites for the major footwear brands, try to ensure that the customer is in the right shoe for his or her foot type.

Interestingly, a few studies have been published recently arguing that there is no statistical proof that the shoe type matters. For this article, I will analyze the merits of one of these studies, entitled “The Effect of Three Different Levels of Footwear Stability on Pain Outcomes in Women Runners” from The British Journal of Sports Medicine (BJSM).

BJSM “Pain Outcomes”

The study in The BJSM began with the hypothesis that the “conventional assignment of footwear stability categories should result in the least amount of pain per foot posture type.” (bjsm.bjm.com)

Step one in the study was to categorize 81 different women into their respective foot types using Redmond et all’s Foot Posture Index. The results split 39 neutral runners, 30 runners who over-pronated, and 12 runners who highly over-pronated into three groups. Next the groups were randomly assigned a Nike neutral (Pegasus), Nike stability (Structure Triax), or Nike motion-control shoe (Nucleus). The women then underwent a 13 week half-marathon training program. Outcome measures were (1) the number of missed training days due to pain and (2) three Visual Analog Scale (VAS) items for pain during rest, running, and daily activities (bjsm.bjm.com).

The half-marathon training program incorporated 3-4 run workouts per week. Weekly training duration was estimated at 20km per week in the beginning to 40-45km at the peak of training. There was also a two week gradual taper until race day. Subject monitoring and pain analysis was measured through two ways: (1) by attendance at a weekly group long run, and (2) via an online web-based questionnaire recording pain levels and missed workouts. (bjsm.bjm.com)

An Analysis of the Methodology

First of all, the study rightly points out that a limitation of the study is that the sample size of only 81 women is exceedingly small. The second limitation that needs to be pointed out is that the women are running an average of 12 miles (approx. 20km) per week in the beginning of the training program and during taper, while maxing out at 27 miles (approx 45km) per week. For the serious runner, these numbers can mimic one day of training! Many runners are completing upwards of 50 mile training weeks, topping out with pro runners like Heidi Westover, for example, who run up to 200 miles per week.

A third point of difference is with the subjective measurement of pain levels and associating missed workouts with the subject’s running shoe. Although the women were ‘required’ to attend to the weekly long runs, a son or daughter’s re-scheduled soccer game or a long week at work could very likely have been the cause of a missed workout or two.

Next, according to the Sport Factory’s Head Coach Matt Russ, volume is a factor of frequency, duration, and intensity. Since there is no control over intensity, some of the injuries could have resulted from certain women training with too much intensity for their current level of fitness.

The final point of difference requires us to take a trip to the local running specialty store. First off, a customer is first put through a gait analysis procedure and the level of over-pronation (or lack thereof) is determined. In step two of the process, the associate brings out three different running shoes that should be an adequate level of support for the runner’s degree of overpronation. Then the associate watches the customer run in each shoe. It is very common for a shoe that seems like it would work for the customer to be an awkward fit once the customer has a chance to run in it. Thus, although the Nike Structure Triax is indeed a reliable shoe, it is not for every runner that overpronates. Nor is the Pegasus for every neutral runner. In fact, the extreme neutrality of the Pegasus may be too flexible for many neutral runners; perhaps the Nike Moto would have been a better choice for those runners. Thus, by limiting the study’s participants to one brand choice, there is a significant likelihood that a neutral runner in the study was hurt because the Pegasus was not the correct neutral shoe for the particular runner. (This applies for the over-pronating runner in the Structure Triax as well.)

Results

Overall, 32% of runners reported running-related pain during the 13-week training period.

Here is an important point from the study not to be overlooked: “… participants wearing the motion control shoe having significantly greater pain than either the stability or neutral shoe.” (bjsm.bmj.com) See the charts below (bjsm.bmj.com), and note that the first chart is Pain at Rest and the second chart is Pain with Running. Also, it is interesting to note that there was great variability in the neutral category. While running, the neutral category reported the lowest levels of pain overall. Thus, pain increased with increased levels of unnecessary stability. A conclusion here is that if you are overstabilized, you are more likely to get injured. Also, if you are an over-pronator who is incorrectly running in a neutral shoe, you are more likely to get injured. The stability category, being in the middle, is the least likely to cause injury at such a low level of weekly mileage. I would argue that if the weekly mileage is bumped up, the increased stress on body coupled with being in the wrong shoe-type, would show results that mirror current beliefs (ie the runner should wear the shoe that mirrors their foot type).

Also, it is noteworthy that every runner who would theoretically need a motion control shoe and was given a motion control shoe reported pain during the study. There are two main points of discussion with this: (1) the sample size was too small to regard this as statistically significant as only 7 runners fell into this category and (2) the women in this category tended to have a higher BMI and thus were more likely to be injured overall. (bjsm.bmj.com)

Regarding the use of the very flexible Pegasus, “[the results of the study] imply that a certain degree of additional stability may be beneficial for those individuals with a neutral foot posture, but too much support may be

detrimental.” I would regard this as information that even for a few of the neutral runners that were ‘correctly’ put in the Pegasus, the shoe was inherently too neutral for their foot type. Perhaps they would have been better served by a shoe in the ‘supportive neutral’ category.

Conclusion

The study concludes with the statements “neutral runners may be best served wearing a stability shoe...and this study is unable to provide support for the convention that highly pronated runners should wear motion control shoes…[Thus] current conventions for assigning stability categories for women’s running shoes do not appear appropriate based on the risk of experience pain when training for a half marathon.”

However, it is necessary to dig deeper into this study rather than just taking its abstract at face value. After breaking apart its control variables (a small sample size, un-monitored training intensity, low frequency and duration of training, and the use of one running shoe brand), it is easy to see that the jury is still out regarding the importance of putting the runner in the ‘right’ shoe type. For now, there is a lot to be said for the seasoned neutral runner who won’t be caught dead in a motion control shoe or vice-versa. For those very serious runners whose primary goal is to not get injured, the shoe "type" most certainly does still matter.

See you on the roads…