One reason heel strike running may be unsustainable from an injury prevention standpoint is that it may cause higher rates of tension and compression on the hamstrings as compared with forefoot running.
In many cases, landing heel-first during running is often accompanied by maximum knee extension (fully unbent knee) at touchdown (shown below). This produces an over-stride which means the initial foot-strike position (i.e the extended leg) is positioned too far ahead of the mass of the body. The major problems with this is 1. the mass of the body collides too intensively with the extended leg at touchdown and 2. the mass of the body collides with the extended leg for a prolonged period of time, too! A consistent consequence of this scenario is that a compressive wave is produced which ripples up the leg, through the hips.
Even worse, the collisional force, and therefore compressive wave, increases in proportion to speed and body-weight during running. In other words, the faster you run and/or the more you weigh, the greater the intensity and duration of the collisional force and compressive wave when you run with an over-stride coupled with landing heel-first. How can hamstring injury arise out of all this?
For one, a fully extended leg (maximum knee extension) at touchdown during running stretches the hamstrings beyond maximum tension during the phase of running (i.e touchdown phase) associated with the greatest production of impact.
Multiple lines of research (listed below the article) speculate that this landing configuration under these high-impact conditions during running may easily give rise to a hamstring injury because of the increased amount of time the hamstrings spend in a maximally stretched state. The other concern is the over-stretched hamstrings spend an increased amount of time enduring high impact. As a result, microscopic muscle damage to the hamstrings may easily arise, and hamstring injury can manifest in this one way.
In contrast, the hamstrings may be less vulnerable to pain and injury in forefoot running because landing forefoot-first during running results in a less extended leg, and therefore less knee extension at touchdown (shown below) which in turn contributes to a shorter stride length where over-stride mechanics can be prevented. Because there’s less knee extension at touchdown in forefoot running, the hamstrings are required to stretch less which directly reduces tension on the muscles.
Even better, the reduced stride length in forefoot running accounts for a big reduction in the collisional force, therefore less compressive loads are transmitted to the hamstrings, too!
Ultimately, these are good reasons forefoot running may bring more help in reducing hamstring injury risk as compared with heel strike running, and is just one of the many great appeals of forefoot running. To that point, there’s a long-list of injuries forefoot running may do a better job at preventing than heel strike running. Read more about it here!
Goss DL and Gross MT. A review of mechanics and injury trends among various running style. AMEDD, Sept -2012.
Heiderscheit B.C., Hoerth D.M., Chumanov E.S., Swanson S.C., Thelen B.J., Thelen D.G. Identifying the time of occurrence of a hamstring strain injury during treadmill running: a case study. Clin. Biomech. (Bristol., Avon.) 2005;20:1072–1078. doi: 10.1016/j.clinbiomech.2005.07.005
Opar D.A., Williams M.D., Shield A.J. Hamstring strain injuries: Factors that lead to injury and re-injury. Sports Med. 2012;42:209–226. doi: 10.2165/11594800-000000000-00000.
Schache A.G., Kim H.J., Morgan D.L., Pandy M.G. Hamstring muscle forces prior to and immediately following an acute sprinting-related muscle strain injury. Gait Posture. 2010;32:136–140. doi: 10.1016/j.gaitpost.2010.03.006.
BSc Neurobiology; MSc Biomechanics candidate, ultra minimalist runner & founder of RunForefoot. I was a heel striker, always injured. I was inspired by the great Tirunesh Dibaba to try forefoot running. Now, I'm injury free. This is why I launched Run Forefoot, to advocate the health & performance benefits of forefoot running and to raise awareness on the dangers of heel striking, because the world needs to know.