Foot dysfunction and cure part 2

"For a ship without a port, no wind is right." (Seneca the Younger)

The function of the foot is not only to support, but also to control the direction of the body's weight during movement (Rolian et al., 2009). Part 1 explained the importance of foot shape in general for these purposes. But the important role of the toe deserves special attention.

The big toe is the rudder that provides directional control for the body weight during weight transfer (Yavuz et al., 2009). This is only possible when it is in the correct position. The marked splaying of this toe from the other toes usually characterizes barefoot walkers (Hoffman, 1905; D'Aout et al., 2009; Shu et al., 2015) and is an evolved functional adaptation that provides directional stability. Chou et al. (2009) showed that forcing the toe into an elevated position resulted in a loss of balance ability. Plank (1995) evidenced excessive pronation during walking when the position of the big toe was compromised (squeezed), a condition that affects 23% of 18-60 year olds and more than 36% of those over 60 years of age (Nix et al., 2010) and results from wearing shoes with a tight toe box (Munteanu et al., 2017).

The unique position and control of the big toe has evolved to manage body weight during walking and running. Impaired toe position leads to instability and harmful stress on the foot, ankle and knee. The therapy is simple:

Wearing foot-shaped (functional) shoes in which the toes have room to spread out and the foot can splay, as well as
Loading the feet with body weight to allow gravity to act on the functional foot shape.

References

Chou S, Cheng HK, Chen J, Ju Y, Wong MA. The role of the great toe in balance performance. Journal of Orthopaedic Research. 2009; 27:549-54.
D'Aout K, Pataky TC, De Clercq D, Aerts P. The effects of habitual footwear use: foot shape and function in native barefoot walkers. Footwear Science. 2009; 1(2):81-94.
Hoffman P. Conclusions drawn for a comparative study of the feet of barefooted and shoe-wearing peoples. The Journal of Bone and Joint Surgery. 1905; 3:105-36.
Munteanu SE, Menz HB, Wark JD, Christie JJ, Scurrah KJ, Bui M, Erbas B, Hopper JL, Wluka AE: Hallux valgus, by nature or nurture? A twin study. Arthritis Care & Research 69: 1421-1428, 2017.
Nix S, Smith M, Vicenzino B: Prevalence of hallux valgus in the general population: a systematic review and meta-analysis. Journal of Foot & Ankle Research3:21.
Plank M. The pattern of forefoot pressure distribution in hallux valgus. The Foot. 1995; 5(1):8-14.
Rolian C, Lieberman DE, Hamill J, Scott JW, Werbel W. Walking, running and the evolution of short toes in humans. Journal of Experimental Biology. 2009; 212:713-21.
Shu Y, Mei Q, Fernandez J, Li Z, Feng N, Gu Y. Foot morphological difference between habitually shod and unshod runners. PLoS ONE. 2015; 10:e0131385.
Yavuz M, Hetherington VJ, Botek G, Hirschman GB, Bardsley L, Davis BL. Forefoot plantar shear stress distribution in hallux valgus patients. Gait and Posture. 2009; 30(2):257-9