Emerging Evidence On Footstrike Patterns In Running

Author(s): 
Kevin A. Kirby, DPM

   However, directly contradicting the findings of the study by Lieberman and colleagues, a more recent study by Hatala and coworkers in 2013 showed that when another group of habitually barefoot Kenyans ran at a much slower and more common recreational running speed of 3.3 m/sec (8:08 mile pace), 72 percent of these barefoot runners were rearfoot strikers, 24 were midfoot strikers and only 4 percent were forefoot strikers during running.7,8Therefore, the idea of Lieberman and coauthors that our ancestors who ran barefoot were predominantly forefoot strikers and were not rearfoot strikers seems unlikely. In addition, the speculation that forefoot striking running is a more “natural” form of running than rearfoot striking or midfoot striking running is not supported by the scientific research literature.

What The Research Reveals: Rearfoot Striking Preferred By Majority Of Runners

In order for the clinician to better understand the footstrike pattern debate and the scientific research on the subject, it is important first to review some of the most significant running research studies involving footstrike patterns.

   In 1980, Cavanagh and Lafortune published the first modern scientific study of footstrike patterns of runners.9 In their study, 17 people ran over a force plate to classify their running footstrike patterns. The researchers divided the anterior-posterior length of the shoe sole into equal thirds with those people who first contacted the ground with the proximal third of the shoe being labelled as rearfoot strikers, those contacting in the middle third being midfoot strikers and those contacting in the distal third of the shoe sole being forefoot strikers. At a 4.5 m/sec (5:58 mile pace) running velocity, 12 of the study participants were rearfoot strikers, five were midfoot strikers and none of the runners were forefoot strikers. In 1987, the term “strike index” first arose within the scientific literature to describe the percentage of the running shoe sole length, from anterior to posterior, where the runner first contacted the ground at footstrike.10

   In regard to the footstrike patterns of the running population as a whole, there have been seven research studies to date that have measured footstrike patterns in large numbers of runners. Kerr and colleagues measured the footstrike patterns of 753 runners in 10 km and marathon distance races, and found that 81 percent were rearfoot, 19 percent were midfoot and 0 percent were forefoot strikers.11 Hasegawa and coauthors studied the footstrike patterns of 283 elite half-marathoners and found that 74.9 were rearfoot, 23.7 percent were midfoot and only 1.4 percent were forefoot strikers.12 Larson and colleagues measured 936 half-marathon runners and found that 88.9 percent were rearfoot, 3.4 percent were midfoot, 1.8 percent were forefoot and 5.9 percent were asymmetrical foot strikers.13

   Out of 903 novice runners, Bertelsen and coworkers found there were 98.1 percent rearfoot, 0.2 percent midfoot, 0.4 percent forefoot strikers and 1.2 percent asymmetrical foot strikers.14 Kasmer and colleagues studied 1,991 runners in a marathon and found that 93.7 percent were rearfoot strikers.15 In a 50 km trail race, Kasmer and coauthors also determined that 85.1 percent of 165 runners were rearfoot strikers.16 Finally, Almeida and coworkers showed that in 514 recreational runners, 95.1 percent were rearfoot strikers, 4.1 percent were midfoot strikers and 0.8 percent were forefoot strikers.17

   Of the 5,545 runners who had their footstrike measured in these seven research studies, 90.8 percent (5,034) were rearfoot strikers (see “Seven Studies Show Rearfoot Striking Preferred Form In Runners” below).11-17 This conclusively demonstrates that the preferred footstrike pattern for the vast majority of runners is rearfoot striking.

Comments

Thank you for the article Dr. Kirby.

With the evidence overwhelmingly in favor of a rearfoot strike pattern and runners finding their own metabolically efficient running style, what do you think is the driving force behind the popularity of minimalist shoes and Pose Running style among some podiatrists?

Kevin A. Kirby DPM's picture

Joe:

I believe there has been an overwhelming amount of misinformation and hype over the last five years being generated by a certain subset of individuals that for some unknown reason want to imagine that somehow, rearfoot striking is bad and forefoot and/or midfoot striking is good for all runners. These erroneous opinions were largely generated by books such as "Born to Run" by Chris McDougall where the author cherry-picked the large database of running biomechanics literature and hand-selected only researchers to interview for his book that favored his barefoot/minimalist shoe message.

In addition, Pose Running, even though popular among a small group of runners, has not been shown to be metabolically more efficient but rather has been found to be more metabolically inefficient. The creator of Pose Running was a coauthor of the article that found his own running form technique classes that runners pay to learn produced less metabolically inefficient running (Dallam GF, Wilber RL, Jadeles K, Fletcher G, Romanov N. Effect of a global alteration on running technique on kinematics and economy. J Sports Sciences. 2005;23(7):757-764).

All in all, the barefoot running and minimalist running fad is slowly dying a slow death here in the USA and in other countries. Runners that tried to convert to barefoot running and minimalist running shoes under the advice of supposed "experts" are now realizing that they drank the proverbial Kool-Aid by listening to and actually believing these "experts" that barefoot and minimalist running shoe running would be the cure-all for all their injuries. Many of them became injured, disillusioned and angry by listening to the hype from these "experts".

However, that being said, the barefoot/minimalist shoe and footstrike controversies over the past five years have served a useful purpose in that it generated significantly more interest in running and running shoe biomechanics that has led to much more research and helped us answer many research questions that could not have been answered five years ago. Hopefully, further research will allow us to better advise our patients and the public on the best running foot strike patterns and running shoe for their specific biomechanical makeup.

Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

Excellent article Dr. Kirby. Finally a balanced piece on the subject and backed by the current evidence instead of hyperbole and opinion.

Kevin A. Kirby DPM's picture

Thanks for the kind comments, David. I agree with you that scientific research evidence should be what drives our opinions on the important subject of foot strike patterns in runners.

In that regard, since I submitted this article for publication, an excellent article on footstrike patterns in ultra-marathon runners has been recently published which showed that a rearfoot strike pattern was again the predominant footstrike pattern in 373 runners in a 100 mile ultra-marathon race. At 16.5 km, the percentage of RF strikers was 79.9%, at 90.3 km was 89.0%, at 90.7 km was 84.8% and at 161.1 km was 83.9%.

In addition, it was found that the post-race creatine phosphokinase levels were significantly higher in the non-RF strikers than in the athletes that were RF strikers, indicating possibly that non-RF strikers may exhibit more muscle damage than RF strikers in ultramarathons (Kasmer ME, Wren JJ, Hoffman MD: Foot strike pattern and gait changes during a 161-km ultramarathon. J Strength Cond Research, 28 (5):1343-1350, 2014).

Much more research is necessary to determine what the optimum foot strike pattern is for each individual runner and how foot strike patterns affect the production of specific overuse injuries in the foot and lower extremities of recreational and competitive distance runners.

Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

Thanks for your valuable summary and for referring to our recent publication Kevin. I agree that the barefoot/minimalist shoe and foot strike controversies have stimulated new knowledge that we otherwise wouldn’t have at this point.

As for our recent study, you mentioned our finding of higher post-race blood creatine phosphokinase (CK) concentrations among non-rear foot strikers compared with rear foot strikers. While this analysis was pre-planned and we recognized a theoretical basis for the findings, it was indeed somewhat remarkable that the group difference reached statistical significance since there is such a wide variability in CK concentrations among the participants in this race.

The finding suggests that a small percentage of highly experienced runners naturally select a foot strike pattern that may neither be most economical nor optimal at limiting muscular damage. I suspect it’s not because these runners need to be re-educated about how to run correctly, but that they had adapted a movement pattern that was most effective for their needs under the circumstances of the event. I favor the concept that humans generally adapt to the most appropriate movement pattern over time, unless overly influenced by outside factors, and that part of our job as scientists is to explain why they do what they do. Some of our thoughts on this are discussed in our publication (Millet GY, Hoffman MD, Morin JB. Sacrificing economy to improve running performance – a reality in the ultramarathon? J Appl Physiology 2012;113:513).

Martin D. Hoffman, MD, FACSM, FAWM
Chief of PM&R, VA Northern California Health Care System
Professor of PM&R, University of California Davis
Research Director, Western States Endurance Run
Chief Medical Officer, Ultra Medical Team

Kevin A. Kirby DPM's picture

Martin:

Thanks for the further information on your research. As you know, foot strike pattern is just one of the many kinematic variables when one is assessing the gait function of runners. Other kinematic variables such as arm swing, stride length, stride frequency, time of double float phase, angle of gait, base of gait and rearfoot pronation/supination may also be important variables that may or may not affect running performance, running efficiency and the production of running-related injuries. In addition, velocity of running also affects foot strike pattern with sprinters nearly always being forefoot strikers and slow joggers nearly always being rearfoot strikers.

One of my biggest frustrations of being involved with the barefoot/shod running and foot strike debate over the past five years is the notion among many of the barefoot/minimalist/anti-rearfoot striking advocates is their belief that 1) foot strike pattern is the most important running kinematic variable and 2) all runners would benefit from choosing to run with an "ideal" non-rearfoot striking pattern. Not only are these ideas not consistent with the current scientific literature, they also don't make sense from my forty years of observation of elite, sub-elite and recreational runners.

Certainly, we must all give the central nervous system of a runner credit that it can, over time, select the most metabolically efficient running form for that runner given that runner's paticular foot and lower extremity structural and functional biomechanical makeup. The fear of mine is that some running coach would read "Born to Run", believe all of the cherry-picked half-truths from that book and then start teaching all his runners to run without rearfoot striking. Unfortunately, I have seen that come true in my own running community. Hopefully, now that the barefoot/minimalist running fad is slowly dying, a little more sanity will prevail in running communities across our great country.

Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

It would have been nice if any of these studies correlated equinus with preferred strike patterns.

Nice article. What about the research on where your foot lands in relation to your hip? I have read articles and supposedly research that it isn't which part of your foot that strikes the ground first but is it in front of your hips or under your hips when it strikes the ground.

Kevin A. Kirby DPM's picture

Foot placement relative to the center of mass (CoM) of the body or to the hip joint during running is important but is not a constant. During acceleration, such as during the start of a sprint, the feet will be well behind the CoM and during deceleration in running, the feet will be well ahead of the CoM. In addition, at faster running speeds, where there is increased force on the body from the force of air pressure posteriorly, the feet will tend to be more posteriorly located relative to the CoM.

I believe that foot placement during running needs much more research before we can say that there is "one best foot placement relative to the CoM" for any one running speed, any one running surface angle or any one wind velocity.

Kevin A. Kirby, DPM

Kevin:

Thank you for an excellent article on this subject.

It would be also interesting to obtain more basic information about the physics pertaining to different running styles. Propulsion involves downward force applied by the forefoot which relates to leverage. The lever arms to look at involve the distance from the ankle joint, the fulcrum, to the forefoot surface involved in propulsion as well as the distance from the insertion point of the Achilles to the ankle joint fulcrum. Midfoot or forefoot striking effectively shortens the lever arm involved in propulsion, thereby potentially decreasing propulsive power or requiring greater force through the gastrosoleus-Achilles complex to achieve the same power.

Ed:

Thank you for your interest in my article.

The scientific research on running biomechanics seems to indicate that rearfoot, midfoot and forefoot striking runners don't differ so much during propulsion but differ more in the initial loading stages of the support phase (i.e. stance phase) of running. In rearfoot strikers, there is an initial impact peak (i.e. passive peak) from ground reaction force (GRF) that is not seen in midfoot and forefoot striking runners. However, there seems to be little evidence to suggest that this impact peak is a cause of running injuries.

Contrary to what you state, there seems to be little evidence to suggest that "midfoot or forefoot striking effectively shortens the lever arm involved in propulsion." The gastrocnemius and soleus are used by all runners, regardless of whether they are rearfoot, midfoot or forefoot strikers, to propel themselves off the forefoot into the double-float phase of running so no change in lever arm during propulsion occurs. Rather, the big differences between these different foot-striking runners is in how they all absorb ground reaction force caused by the body decelerating the center of mass of the body falling downward during the first half of the support phase of running.

Kevin A. Kirby, DPM

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