Arch recoil does not move the body( COM) upwards and forwards, it does the opposite

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Until recently, it was thought that energy stored in the soft tissues of the foot during gait helped propel the body forwards and upwards during the later stages of gait when the energy was returned. A new paper suggests the opposite may be true! That is to say, arch recoil lowers and posteriorly translates the body (COM).

"However, recent work has shown that arch recoil lowers and posteriorly tilts the talus, lowering and posteriorly translating the COM." Yetman et al

Reconciling how positive foot power drives the arch recoil mechanism

Quinn Yetman 1, Lauren Welte 2 3, Aidan Shimizu 1, Michael J Rainbow 1
Affiliations Expand

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  • PMID: 41633524
    
  • DOI: 10.1098/rsif.2025.0532

 

As referenced in Yetman et al, a second research group has produced evidence that arch recoil is a vital part of gait, not in the sense that it directly contributes to propelling the COM forwards , but rather by helping optimize pelvis position by leading it backwards ( not propelling it forwards ) .

The paper is authored by Barsante et al 2024, https://doi.org/10.1123/jab.2023-0072, and includes the following text :

"We observed that the MJC ( midfoot joint complex)plantarflexion (arch raising) during the midstance and late stance leads the pelvis backward, avoiding excessive forward displacement. .....The findings suggest that the MJC is part of the kinematic chain that determines pelvis positions during walking and is functionally coordinated with the lower limb joints."

I think the work being done in the area of arch recoil and its effects on foot and ankle mechanics by Welte, Rainbow, Yetman et al, is likely to be considered seminal in the future. The idea that the "foot spring" does not propel the body forwards but instead allows the talus and hence the lower leg (tib/fib) to be optimally orientated during gait is a major development.

In many individuals arch recoil may be a modifiable factor and the muscles within the foot, the intrinsic foot muscles, may have a key role to play. This might be particularly true of agility-based manoeuvres where the heels only lightly touch the ground if at all.

During walking or running in a straight line the foot accepts load and flattens. This stores energy in the foot ligaments, fascia and muscles. As gait progresses, we now know that arch recoil moves the centre of mass down and back allowing optimal alignment of the ankle and aiding propulsion. This mechanism, and the energy related contribution made by the intrinsics may be of particular importance during "up on the toes", " fast feet" agility tasks, for example, side to side movement in tennis. Research has shown that subjects with better agility results tend to have stronger toe flexor muscles as measured by the system shown in figure (B)

 

Many people with flat feet have no related problems, but of those that suffer from pain in the foot or lower limb a combination of orthotics and foot strengthening seems to be of most help. That is to say, orthotics help, foot strengthening helps, but the best results come from combining the two.

Yes, compliance is far easier when it comes to using orthotics, but if a patient is also taught strengthening exercises they can use these if pain levels start to rise. They have some measure of control.

Why do some people with flat feet have musculo-skeletal problems and some not? It may, at least in part, be more about arch formation during recoil rather than a longitudinal foot arch during midstance . Recoil places the ankle and pelvis in the optimal positions for gait whereas lack of recoil may give a chimpanzee like gait. I have read that flat feet can lead to a slouched gait and poor body posture but perhaps the main problem is feet that have reduced arch recoil .