Do we all have feet half as strong as they should be ?

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This abstract was just published on the internet .

Basically , adolescent female gymnasts where found to have 80-86 % greater toe flexor strength than adult male sports students .

Could it be that the norm for toe flexor strength in the shod population is much lower than that in the unshod ,natural state .
Should everyone be strengthening their toe flexors ?

Toe flexor strength in elite female gymnasts compared to toe flexor strength-trained men

AutorInnen

• Jan-Peter Goldmann
• Marvin Zedler

Details

Introduction
There is some evidence that intrinsic foot muscles propel the body forward during locomotion [1]. Nearly 80% of intrinsic foot muscles consists of toe flexor muscles (TF) [2] proceeding from the heel to the distal phalanges of the toes. TF’ strength capacity has the potential to enhance jump performance [3]. Since the ability to jump is a performance-limiting factor in gymnastics, we hypothesized that elite female gymnasts’ TF strength is higher than in male sport students, but similar to TF strength-trained men.

Methods
28 female gymnasts (15 ± 2 y, 47 ± 9 kg, 1.56 ± 0.09 m) of the German national team and a basic control group of sport students (n = 28, 25 ± 3 y, 77 ± 8 kg, 1.83 ± 0.06 m) performed three maximum voluntary isometric contractions (MVC) of TF for each foot. TF strength was determined by measuring the moment about the transverse axis of a custom-made dynamometer in 25 degrees toe dorsiflexion. The external moments of force about the axis represented the moments of force produced by the TF [3]. The best of three trials was used for further analysis. Peak moments were determined as the mean value of a 2 s time window of the plateau region. Data were compared to a previous study with the same dynamometer, where a TF strength training group (15 men, 24 ± 4 y, 77 ± 9 kg, 1.85 ± 0.07 m) performed a heavy resistance TF strength training with 90% of MVC for 7 weeks [3]. Statistics: Kolmogorov-Smirnov, unpaired t-test.

Results and Discussion
TF strength significantly differed (p < 0.001) between elite female gymnasts (left: 0.41 ± 0.08 Nm kg-1, right: 0.45 ± 0.09 Nm kg-1) and male sport students (left: 0.22 ± 0.05 Nm kg-1, right: 0.25 ± 0.06 Nm kg-1). There were no significant differences (p > 0.05) between the TF strength of elite female gymnasts and the male strength training group after 7 weeks of TF strength training (left: 0.38 ± 0.07 Nm kg-1, p = 0.07, right: 0.40 ± 0.08 Nm kg-1, p = 0.07).
Adolescent female gymnasts showed 80% to 86% higher TF strength than male sport students, but nearly the same strength level as adult men after 7 weeks heavy resistance TF strength training [3].

Conclusions
TF in elite gymnastics seem to be highly loaded and have to be of particular interest for training and performance enhancement.

References
[1] Farris et al. (2019). PNAS, 116: 1645-1650.
[2] Kura et al. (1997). Anat Rec, 249: 143-151.
[3] Goldmann et al. (2013). J Sport Sci, 31: 424-433.

Originalsprache	Englisch
Titel	Proceedings of the International Society of Biomechanics 2021
Erscheinungsdatum	25.07.2021
Publikationsstatus	Veröffentlicht - 25.07.2021
Veranstaltung	28th Congress of the International Society of Biomechanics - online Dauer: 25.07.2021 → 29.07.2021

 

I suspect it's not so much the running and jumping that makes the feet of gymnasts strong, but the unshod nature of the activity .

 

Researchers looking into foot mechanics have long , and reasonably, taken the toe flexor strength of healthy individuals from the shod community to be the norm . These norms have then been used as comparators for interventions and the study of toe flexor impacting pathologies .

But now it looks like the toe flexor strength of such individuals ,even athletic young males ,may only be a fraction of what the natural ( unshod ) levels should be . Probably only about half .

It seems is pretty clear to me that shoes greatly impact upon toe flexor strength .

 

Some authorities have suggest that using minimal shoes strengthen feet and that walking about in "supportive shoes" is ultimately a bad thing for our feet .

Goldmann's conference paper throws aspects of this into question and it begins to look like it is not the supportive element of shoes that cause weakness but rather it is the artificial grip they provided .

When the gymnasts run and jump barefooted, they naturally press the toes into the ground to prevent rotation around the ball of the foot . I believe it is this pushing down action during locomotion that maximally activates the toe flexors ,many of the intrinsics included .

By way of explanation here is a quote from a thread I wrote some time ago-

"First I found myself a suitable surface such as linoleum . Next I took off my shoes and socks and stood next to a wall for support . Then , taking most of my weight initially on the right foot which was kept flat on the ground ,I put my left foot into toe off position so that only the ball of the foot and the toes were in contact with the ground . Then I carefully transferred some weight onto the left foot and finally,with the ball of the foot and toes under some pressure , rotated the foot outwards producing torque . I found that the toes played an important part in resisting the outward rotation and that they also began to become spaced out from each other possibly engaging the adductors .( please note that I am not suggesting that anyone copy the above exercise sequence or injury may result )"

In light of Goldmanns paper, it begins to look to me that orthotics will produce very little additional weakening of the foot than a minimal shoe would if that minimal shoe encloses the forefoot area and provides grip, taking the job away from the toes .

 

Endo 2002
TFS 39.1% higher in males than females

Nihal 2002
"average TFS slightly higher in dancers than non dancers"

Goldmann 2021

female gymnasts TFS 80-86% higher than males ! Huge differences . IMO explanation lies in shod /unshod, not run jump activity .

Amazed

Little wonder strengthening the foot was found in the Sacco study to half running injuries, if we all have pathetically weak feet to begin with .

 

Endo 2002 found that toe flexor strength was 39.1% greater in men than women but also found -

" However, when normalized by body size (body weight × height), the gender difference in strength no longer reached statistical significance."

So toe flexor strength varied with weight and height .

Elite, adolescent, female gymnasts are ,on average shorter than average height and much lighter . In the UK, a mature woman is about 5 feet 3 inches and 154 pounds .The average height of an elite gymnast is 5 feet 1 and less than 100 pounds .

Given that Endo found that toe flexor strength is closely related to height and weight you might expect smaller and much lighter gymnasts to have lower toe flexor strengths than much larger average women. But they don't , they have toe flexor strengths 80-86 % higher than adult male sports students .

Goldmanns paper reads almost like a mouse has been found that kicks harder than a kangaroo .