Muscle Activity Differences in Forefoot and Rearfoot Strikers

Different running techniques load different tissues in different runners differently which has implications for subject specific differences in running economy and running injury risk profile. In that context it was nice to see this turn up:

Differences in Muscle Activity between Natural Forefoot and Rearfoot Strikers during Running
Jennifer R. Yong, Amy Silder, Scott L. Delp
Journal of Biomechanics; Articles in Press
Running research has focused on reducing injuries by changing running technique. One proposed method is to change from rearfoot striking (RFS) to forefoot striking (FFS) because FFS is thought to be a more natural running pattern that may reduce loading and injury risk. Muscle activity affects loading and influences running patterns; however, the differences in muscle activity between natural FFS runners and natural RFS runners are unknown. The purpose of this study was to measure muscle activity in natural FFS runners and natural RFS runners. We tested the hypotheses that tibialis anterior activity would be significantly lower while activity of the plantarflexors would be significantly greater in FFS runners, compared to RFS runners, during late swing phase and early stance phase. Gait kinematics, ground reaction forces and electromyographic patterns of ten muscles were collected from twelve natural RFS runners and ten natural FFS runners. The root mean square (RMS) of each muscle’s activity was calculated during terminal swing phase and early stance phase. We found significantly lower RMS activity in the tibialis anterior in FFS runners during terminal swing phase, compared to RFS runners. In contrast, the medial and lateral gastrocnemius showed significantly greater RMS activity in terminal swing phase in FFS runners. No significant differences were found during early stance phase for the tibialis anterior or the plantarflexors. Recognizing the differences in muscle activity between FFS and RFS runners is an important step toward understanding how foot strike patterns may contribute to different types of injury.

I won’t get into the details, but they basically collected kinematic, kinetic and EMG data in 12 rearfoot strikers and 10 forefoot strikers while runners on a treadmill at 4.0 m/s. Some may have an issue with the treadmill use. Other than that nothing in the handling of data and its analysis jumps out at me as problematic.

They found:

  • tibialis anterior muscle: lower activity in late swing in FFS; no differences in early stance
  • medial and later gastrocnemius muscle: more activity during late swing in FFS; no differences in early stance
  • soleus muscle: no differences in late swing; maybe less active in early stance in FFS (issues to do with correlations and significance levels that I won’t get into; see the paper)
  • rectus femoris: no differences
  • vastus medialis; more active in RFS in late swing; no differences in early stance
  • medial hamstrings: no differences
  • lateral hamstrings: more active in RFS in late swing; no differences in early stance
  • glueteus medius: no differences

Basically, during early stance there were no differences in muscle activity and during late swing, the forefoot strikers showed more activity in gastrocnemius and less activity in the tibialis anterior, vastus medialis and lateral hamstrings.

What this means is that: Different running techniques load different tissues in different runners differently which has implications for subject specific differences in running economy and running injury risk profile.

What this study did not show is: One running technique is not better than another.

As always, I go where the evidence takes me until convinced otherwise

Yong, J., Silder, A., & Delp, S. (2014). Differences in Muscle Activity between Natural Forefoot and Rearfoot Strikers during Running Journal of Biomechanics DOI: 10.1016/j.jbiomech.2014.10.015

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3 Responses to Muscle Activity Differences in Forefoot and Rearfoot Strikers

  1. Ellen October 27, 2014 at 9:50 am #

    Just a small comment: In the list (and research) it’s all late swing, but you conclude by mentioning early swing.

    • Craig Payne October 27, 2014 at 9:52 am #

      Whoops. Thanks. Typo. Fixed it.

  2. Roman R. November 5, 2014 at 10:37 am #

    Am I right to assume that depending on what you are looking at, muscle activity may be negative aswell as positive?
    In terms of energy expenditure a higher muscle activity is certainly a disadvantage but on the other hand, active muscles may have a protective function in terms of stabilization and force dissipation.
    For example, it’s relatively easy to hang passively with your shoulder extended on your arms, compared to doing the same thing with flexed shoulder muscles, keeping your shoulder down. While hanging passively you might win the “who can hang the longest competition” a couple of times until your tendons are overstretched and you ultimately expose yourself to a much high risk of shoulder luxations and tendonitis.
    Having that in mind, can’t be somewhat similar be the case for the lower extremity?
    Thats where I have a problem with chi running when they tell you: “relax your muscles”, where I think, ask your passive structures (e.g. meniscii and ligaments) a couple of years later on if they had the same relaxed sensation.
    I feel it’s a good trade off to run with higher muscle activity (especially when it comes to preactivation), having a greater energy expenditure and maybe having to deal with sore muscles for a couple of days, than having to deal with osteoarthritis the rest of my life…

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