Is lack of arch recoil more important than over pronation?

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Is lack of adequate arch recoil during gait as important or even more important than the degree of pronation?

Recently, Welte, Rainbow et al demonstrate that lack of arch recoil during gait can lead to a tibia which "tilts to far fowards during late stance " , my words, and "can adversely affect the entire kinetic chain, foot to head" again my words.

This piece of work may provided the key to improving many of the skeletal problems encountered by health care professionals.

So how do you improve arch recoil ?

1
Prevent the foot from getting into a very deep pronation which it can't easily get out of , so perhaps some form of arch support. (A bit like half squats rather than full depth )

2
Strengthen the tissues that assist with arch recoil . The intrinsic foot muscles would be the obvious target here . So we are looking at muscle which span the full arch or cross at least one joint in the medial arch of the foot.
These would include abductor hallucis, adductor hallucis , flexor digitorum brevis, flexor hallucis brevis etc

3
Improve arch flexibility esp at cuneonavicular joint.

Note . IMO it is important that the toe flexors become properly active at heel off . So, more retro shoes with reduced toe spring and flexible soles.

If you have PFP it may well be related to lack of arch recoil and excessive "tibial tilt" . Perhaps some running styles are effective at reducing injury because they mitigate the limitations of poor arch recoil.

Welte et al https://www.frontiersin.org/articles/10.3389/fbioe.2023.1155439/full

 

Research shows that if we move from a modern shoe with a stiff sole and a toe spring, to a shoe without these features, the toe flexor power will get increase by about 60% . In all likelihood the foot will go back to its previous strength levels if the shoes are swapped back.

It seems logical that if we wish the intrinsics to contribute more to reducing stress in the plantar fascia, and facilitate arch recoil, we need to strengthen the intrinsics and encourage them to activate. Modern shoes likely reduce intrinsic activity regardless of starting strength.

IMO, more minimal shoes, like deck shoes, will encourage the toes to press down more during gait, which will help support the medial longitudinal arch and aid arch recoil.

 

The intrinsic foot muscles will contribute to arch recoil dependent on their strength and degree of activation . It seems fair to assume that arch recoil does not lead to strengthening of the intrinsics, in and of itself.

Tasks other than arch recoil strengthen the intrinsics which contribute to recoil. Likely IMO , weak intrinsics> less recoil> increased tibial tilt> alternative gait strategies> skeletal pain over time esp with runners.

 

IMO, it may not be so much flat feet that cause problems but rather the failure of the foot to form an arch during toe off to give a "properly" orientated tibia. A person may have congenital flat feet when viewed in a standing position, however, so long as positive work from the foot gives an arch during the later part of gait, the tibia will still be within the optimal functional zone and not tilted forwards like a chimpanzee's.

So a person may have " flat feet" but no functional problems/pain because the foot has a medial arch during toe off. Conversely, a person may have a distinct medial arch when they are standing still but no arch through toe off since the foot is weak and or inflexible.

Potential gold from Welte, Rainbow et al in their paper https://doi.org/10.3389/fbioe.2023.1155439…

 

The windlass mechanism will also contribute significantly to arc recoil through toe off . As the toes dorsiflex so the PF will wind around the heads of the metatarsals helping to reform the medial arch. This is likely going to be negatively influenced by toe springs which reduce toe dorsiflexion through the later stages of gait.

 

Be difficult to establish a tibia being, "too far forward" as a causative mechanism for any msk injury beyond the knee. Especially as tissues will adapt to most things if the dose doesn't exceed capacity. In fact 'knees over toes training', is a popular training modality amongst barefoot/CrossFit crowds currently who you suggest will have the strongest intrinsic musculature.

Would also be difficult to explain why the vast majority of elite athletes and weekend warriors alike remain injury free wearing traditional sports shoes.

Likely it would be patient specific and I would accommodate increasing capacity for loads needed barefoot in athletes performing barefoot. A lot of bold claims going into minimalist shoes for intrinsic strength. I often see people who just aren't biomechanically sound on a 90 degree plane 24/7 in a minimalist shoe and would actually benefit from Orthoses/footwear to mitigate load and allow greater recovery/capacity when performing their chosen endeavour.

A bloke running 10k twice a week and jumping rope twice a week wearing a plush hoka shoe will almost certainly have stronger intrinsics than some hippie in a barefoot shoe wiggling his toes around I'll wait for the RCT on that one though

 

Why beyond the knee ?

Not really relevant in the present context.

Not actually true .

Are shoes with a flexible sole and a reduced toe spring "minimal" . Note I have included arch support as a potentially good thing with regard to arch recoil. I am advocating stronger intrinsics and shoes which allow them to function.

That's not what the research, including already published RCTs, is indicating.