Center Mass Position in Forefoot Running Prevents Energy Loss

Forefoot running prevents energy loss in many ways. One way is by reducing the horizontal distance between the center mass and initial foot strike position.

In forefoot running, your center mass needs to be near your initial foot strike position. How come? The payoff is less energy expenditure, especially at faster running speeds and I will explain why in a moment. In contrast, a larger horizontal distance between the center mass and initial foot strike position increases braking and is typically associated with heel strike running.

The usual method of biomechanics recommends running upright and to never slouch forward. However, running too upright increases the distance between the center mass and initial foot strike position. Therefore, you are better off to slouch forward, like most Kenyan distance runners.

Center Mass Position in Forefoot Running Prevents Energy Loss
Shown above is a heel strike runner with a long horizontal distance between the center of mass and initial foot strike position. This is due to posterior acceleration of the trunk and results in greater braking forces.

Keeping the Distance Between Your Trunk and Foot Strike Position Small

There are 4 factors involved in shortening the horizontal distance between your trunk and initial foot strike position during forefoot running:

1. Reduce anterior posterior trunk sway
2. ‘Lock’ center of mass in anterior position
3.  Increase cadence
4. Reduce stride length

Anterior posterior trunk sway affects the horizontal distance between the center mass and initial foot strike position. If the trunk sways back and forth, the horizontal distance between the trunk and initial foot strike position will correspondingly increase and decrease. Runners do best when they have minimal anterior posterior trunk sway and if they manage to keep their center mass more anterior relative to the lower leg (Mero et al., 1992).

Ultimately, stabilizing the trunk allows the horizontal distance between the center mass and initial foot strike position to remain relatively constant. However, the key is to keep this distance as short as possible.

  • A runner may have minimal trunk sway, yet exhibit a horizontal distance between the center mass and initial foot strike position that is larger than normal. Again, heel strike runners are a perfect example of this.

Furthermore, higher cadence reflects a shorter stride length, which keeps the center mass near initial foot strike position during forefoot running.

  • In contrast, a longer stride length induces posterior acceleration of the trunk which increases braking and press force of the lower extremity during running.

Another benefit to having a small horizontal distance between center mass and initial foot strike position is that it reduces mechanical work at the knee.  Here’s a video showing how to use your center mass to making running easier on your knee:

The Take Home Message

A large horizontal distance between the center mass and initial foot strike position may account of the far slower turnover rates in a typical heel striker as compared to a forefoot runner.

The first step is to push your center mass forward when forefoot run and avoid reaching out with your swing leg. Nonetheless, a forward center mass position is mostly where your momentum comes from which is why shifting the center of mass back results in braking.

Bowflex.com

 

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References:

Lin et al. Impact of center of mass acceleration on the performance of ultramarathon runners. J Human Kinetics, 2014;44, 41-52.

Mero A, Komi PV, Gregor RJ. Biomechanics of sprint running. A review. Sports Med, 1992; 13: 376-392

Mero A, Komi PV, Gregor RJ. Biomechanics of sprint running. A review. Sports Medicine, 1992; 13(6): 376-392

Bretta Riches

Bretta Riches

"I believe the forefoot strike is the engine of endurance running..."

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.
Bretta Riches

P.S. Don't forget to check out the Run Forefoot Facebook Page, it's a terrific place to ask questions about forefoot running, barefoot running and injury. I'm always happy to help!

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