[Via Athletic Lab] Mechanics of Forefoot Running by Gaby Smith

This content was originally posted on athleticlab.com.

[This is a guest blog by Gaby Smith. Gaby Smith completed her MS in Exercise Science at Northeastern University and is participating in the Athletic Lab Mentorship Program. Gaby is a Certified Strength and Conditioning Specialist and holds certifications with U.S. Soccer, USAW, and USTFCCCA.]

Today’s market is full of many different types of running footwear claiming to help runners run more efficiently, improve performance, and reduce the likelihood of injury. Minimalist footwear claims to help runners strike more on the forefoot, while traditional footwear provides more cushioning and promotes a heel first landing. Even with the technological advancements in running shoes, up to 79% of endurance runners are injured in a given year, with almost half (46%) of these injuries being recurrences (Davis et al., 2017). While the causes of these injuries are multifactorial, one of the hypothesized reasons for the high injury rate is the altered rear foot strike pattern promoted by cushioned running shoes. This change in loading and mechanics may not provide the optimal mechanical environment for the foot and ankle compared to the forefoot striking pattern commonly seen when barefoot or wearing minimalist running shoes.

Background

Humans have been running for millions of years. The modern running shoe was not invented until the 1970s, so for most of evolutionary history runners were barefoot or wore very minimalist footwear like sandals or moccasins (Lieberman et al. 2010). Runners were able to cope with the impact of the foot colliding with the ground using a predominately forefoot strike before bringing down the heel. Today, habitually shod runners rear-foot or heel strike as a result of the elevated and cushioned heel of modern shoes. Kinematic analysis shows that forefoot striking generates smaller collision forces because of the plantarflexed foot and increased ankle compliance during impact (Lieberman et al., 2010). This type of striking pattern and gait may protect the feet and lower limb from impact related injuries experienced by many runners.

Modern Running Shoes and Heel Striking

Most modern running shoes feature large cushioned heels for a comfortable and stable landing which cushions some of the force of impact and distributes the force over a larger area of the rear-foot (Liberman et al. 2010). They also typically have arch support and stiffening elements to prevent overpronation (rolling in of the foot) and prevent the flattening of the arch.

Hasegawa et al. (2007) estimate that 75% of shod runners heel strike. This may be because it is comfortable to have the shock-absorbing features cushion the impact, there is more cushioning in the rear-foot than the forefoot, and it is stable. Most likely, the higher heel makes it easier to heel strike because the sole below the heel is about twice as thick as the sole beneath the forefoot (Hasegawa, 2007). While there is nothing wrong with heel striking, some runners may get repetitive stress injuries each year using a rear-foot strike (Lieberman et al., 2010).

At impact, the foot and lower leg come to a dead stop, leading to a high impact transient of about 1.5 to 3 times bodyweight within 50 milliseconds of striking the ground (Lieberman et al. 2010). While many running shoes make heel strikes more comfortable because they slow the rate of impact and spread the force over a greater area of the foot, they do not eliminate the high impact nature of the strike.

Forefoot Striking

Humans have been running for millions of years with a primarily forefoot or midfoot strike pattern. These strikes lead to lower force impacts which likely lead to lower rates of injury than heel striking. Forefoot striking has also been found to strengthen the muscles in the foot and arch, which may also help prevent injury. Forefoot striking may also be more efficient because it uses the natural “springs” in the foot and calf to store and release energy (Lieberman et al. 2010). Running barefoot or in minimalist shoes, which are typically lighter than traditional running shoes, mean that there is less mass to accelerate at with each stride and has been shown to use up to 5% less energy than traditional shod running (Divert et al., 2005; Squadrone & Gallozzi, 2009).

In a forefoot strike, the forefoot will come to a dead stop upon ground contact, but the heel and lower leg continue to fall as the ankle flexes. This type of impact produces essentially no impact transient impact forces up to seven times lower than those experienced by shod runners who heel strike (Lieberman et al. 2010).

Transitioning to Forefoot Striking

While there is nothing wrong with rear-foot striking, transitioning to forefoot striking may reduce the risk of repetitive-use injuries and offer other benefits. Barefoot or minimalist running is most often associated with a forefoot striking pattern; however, most modern footwear alters runners’ striking pattern to a predominately rear-foot striking pattern (Lieberman et al., 2010). Forefoot running loads the plantar fascia, Achilles tendon, and gastrocnemius more efficiently and may optimize their adaptation to the force of impact (Sinclair et al., 2015). In addition to strengthening the muscles of the feet and calves, the force of impact is not as violent as that of a rear-foot strike (Davis et al., 2017).

Converting to a forefoot striking pattern should be done slowly and should be accompanied by foot and lower leg strengthening exercises to minimize injury during the transition of gait. As a result of wearing modern shoes, the muscles of the foot and calf are probably weak and will require great strength to contract eccentrically to lower the heel following landing (Lieberman et al., 2010). If transitioning, build up slowly and stretch the calves, hamstrings, and arches frequently to help repair the muscles. Thick soled shoes are also more forgiving when running on uneven surfaces, so minimalist running may be more comfortable on a hard but smooth surface such as a tennis court, track, or smoothly paved road. While forefoot striking is associated with lower impact forces and potentially lowers the rate of impact-related repetitive use injuries, the transition from rear-foot to forefoot striking must be done slowly and with caution as to prevent overusing weak muscles potential injury.

Key Takeaways

  • Modern footwear promotes a rear-foot strike pattern which may be associated with the high rates of repetitive use injuries runners experience
  • Forefoot striking lessens the force of impact by allowing the heel to continue to lower towards the ground and lengthen as the ankle flexes
  • Forefoot striking strengthens the muscles of the foot, arch, and calf

References

  • Divert C, Mornieux G, Baur H, Mayer F, Belli A. Mechanical comparison of barefoot and shod running. Int J Sports Med. 2005 Sep;26(7):593-8. doi: 10.1055/s-2004-821327. PMID: 16195994.
  • Hasegawa H, Yamauchi T, Kraemer WJ. Foot strike patterns of runners at the 15-km point during an elite-level half marathon. J Strength Cond Res. 2007 Aug;21(3):888-93. doi: 10.1519/R-22096.1. PMID: 17685722.
  • Lieberman, D., Venkadesan, M., Werbel, W. et al. Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature 463, 531–535 (2010). https://doi.org/10.1038/nature08723
  • Moody D, Hunter I, Ridge S, Myrer JW. Comparison of Varying Heel to Toe Differences and Cushion to Barefoot Running in Novice Minimalist Runners. Int J Exerc Sci. 2018 May 1;11(1):13-19. PMID: 29795721; PMCID: PMC5955330.
  • Sinclair J, Atkins S, Richards J, Vincent H. Modelling of Muscle Force Distributions During Barefoot and Shod Running. J Hum Kinet. 2015 Oct 14;47:9-17. doi: 10.1515/hukin-2015-0057. PMID: 26557186; PMCID: PMC4633245.
  • Squadrone R, Gallozzi C. Biomechanical and physiological comparison of barefoot and two shod conditions in experienced barefoot runners. J Sports Med Phys Fitness. 2009 Mar;49(1):6-13. PMID: 19188889.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s