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 .

 

Yetman,Welte et al have proposed the "arch recoil–upright gait hypothesis" in which recoil of the foot's medial arch moves the COM back and down compared to a rigid foot ( and not upwards and forwards )thus orientating the ankle for optimal function. A number of tissues likely contribute to energy storage and return and one can speculate that foot muscles may make active contributions via concentric contraction.
So is there any evidence that the intrinsic foot muscles make an active contribution to arch recoil and hence are an important component of the arch recoil-upright gait hypothesis?


A few years ago a paper was published that looked at the effects of a selective tibial block on vertical jump performance. A contribution from the intrinsic foot muscles was believed to "modulate plantar flexor gearing and ankle joint contributions" In light of the arch recoil upright gait hypothesis it may be that recoil moves the talus back and down allowing the foot to remain on the ground longer than would be the case without recoil . Hence greater vertical jump height when the intrinsics are involved.
Examining the intrinsic foot muscles’ capacity to modulate plantar flexor gearing and ankle joint contributions to propulsion in vertical jumping

Author links open overlay panelRoss Smith a, Glen Lichtwark a, Dominic Farris b, Luke Kelly a
https://doi.org/10.1016/j.jshs.2022.07.002


Highlights

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  Metatarsalphalangeal joint quasi-stiffness during jumping was reduced by the application of a selective tibial nerve block, which removed the active contributions of the intrinsic foot muscles
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  When jumping under the nerve block, ankle leverage and torque were reduced when compared to normal conditions
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  Fascicle and muscle–tendon unit velocity were not different during jumping propulsion between normal and nerve block conditions
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  Although impulse was similar between conditions, jump height was reduced under the nerve block condition due to a lower take-off position of the center of mass

 

During gait the foot initially tends to flatten . As gait progresses through toe off the arch recoils allowing the ankle joint to be optimally orientated.
Lots of muscles contribute to arch stability and recoil including the intrinsic foot muscles ,tibialis posterior ( perhaps the biggest contributor) peroneal muscles and the FHL &FDL .

Arch recoil can probably be improved by doing arch recoil activities, for example the short foot exercise (doming). That's probably why this exercise works, it's not so much about improving arch support as improving arch recoil.