I have a lot to say about my first love… running. For myself there is nothing more meditative than feeling the ground under my feet on a long, hard run. And as distance running has rapidly gaining popularity, it is easy to see why many people would have similar blissful experiences while running. However, despite our growing interest in the sport, incidence of running injuries are consistently reported between 60-80% and these numbers may be rising.1,2 So what is it about running that is causing so much grief for those who enjoy it?
One contributing factor to running injuries that is continually being studied is vertical loading rates. No matter the person or their technique, a runner will contact the ground with a force of one and a half to three times their body weight.3 Ground reaction force is the ground’s response to this impact. It is the vertical component of this impact that is of interest to us – the vertical loading rate.
Vertical loading rates have been repeatedly linked to running overuse injuries in both prospective and retrospective studies.4,5 Thus, if we can learn to properly absorb this impact we can help prevent the epidemic of running injuries. This is what popularized many of the running advice we see today. One example of a now somewhat infamous diagram is explained below.
This diagram represents how foot strike can influence the high impact of running, and is exactly why the barefoot running and minimalist shoe trend became popular. The body has a natural ability to absorb vertical impact forces and using a forefoot strike method is one way to encourage shock absorption (think landing on your forefoot versus your heel when skipping rope). There are a few ways to encourage a mid to forefoot strike when running. The first is to increase your running cadence. An increase in cadence of 5-10% (or a standard 180+/- 10 steps per minute), has been found to encourage a more plantar flexed foot and increased knee bend knee at initial contact, as well as a footstrike pattern more directly under a person’s center of mass.6
To assist with some of this biomechanical knowledge transfer, I have included 3 video analysis of a female runner below as a clinical example of how shoes alone can immediately change biomechanics. The healthy runner in this video was taped in three situations: traditional running shoes, minimalist shoes, and barefoot. All videos were taken in succession with no delay for training or even cuing during the process.
This will help explain how vertical impact can result in pain, and why improved running mechanics are used to absorb these forces. Though perfect running form can be accomplished with any types of shoes, it is easier to feel the ground with thinner shoes so it may assist with changing form. Though minimalist shoes are not meant for all runners, good form is. I would encourage you to consult your physiotherapist for assistance before making drastic changes to your running shoes or form.
By Amy Fahlman
BSc PT, MCl Sc (manip)
- Van Middelkoop M, Kolkman J, Van Ochten J, Bierma-Zeinstra SM, Koes BRistolainen et al, 2010. Prevalence and incidence of lower extremity injuries in male marathon runners. Scand J Med Sci Sports. 2008 Apr;18(2):140-4. Epub 2007 Jun 6.
- Ristolainen L, Heinonen A, Turunen H, Mannström H, Waller B, Kettunen JA, Kujala UM. Type of sport is related to injury profile: a study on cross country skiers, swimmers, long-distance runners and soccer players. A retrospective 12-month study. Scand J Med Sci Sports. 2010 Jun;20(3):384-93. doi: 10.1111/j.1600-0838.2009.00955.x. Epub 2009 Jul 2.
- Lieberman DE, Venkadesan M, Werbel WA, Daoud AI, D’Andrea S, Davis IS, Mang’eni RO, Pitsiladis Y. Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature. 2010 Jan 28;463(7280):531-5.
- Zadpoor AA, Nikooyan AABredeweg, 2012. The relationship between lower-extremity stress fractures and the ground reaction force: a systematic review. ClinBiomech (Bristol, Avon). 2011 Jan;26(1):23-8. doi: 10.1016/j.clinbiomech.2010.08.005. Epub 2010 Sep 16.
- Bredeweg SW, Kluitenberg B, Bessem B, Buist I. Differences in kinetic variables between injured and noninjured novice runners: A prospective cohort study. J Sci Med Sport. 2012 Aug 23. [Epub ahead of print].
- Heiderscheit BC, Chumanov ES, Michalski MP, Wille CM, Ryan MB. Effects of step rate manipulation on joint mechanics during running. Med Sci Sports Exerc 2011;43(2):296–302. 7. Taunton JE, Ryan MB, Clement DB, McKenzie DC, Lloyd-Smith DR, Zumbo BD. A retrospective case-control analysis of 2002 running injuries.Br J Sports Med. 2002 Apr;36(2):95-101.