How does plantar fascia do it?
The perfect example to describe this is to imagine a rope that stretches as you put weight on your foot and then retracts. Balancing certain movements with your foot - pronation and supination - allows your foot to transfer energy and propel you forward.
The word "plantar" is used to represent the "lower part of your foot".
Keep in mind that the plantar fascia turns out to be the most important stabilizing structure in the arch of your foot. It elongates with increasing loads and stores "elastic" energy which acts as a shock absorber. It is this part that works in synergy with the multitude of ligaments between the bones of the foot.
Although it has an impressive absorption capacity, it is different for its ability to lie down, which is very minimal. It is essentially a semi-rigid "rope" that, once it has reached its maximum capacity, becomes stiff with tension.
Take the test yourself:
You can dorsiflex so that you can see the effect of this mechanism. In other words, you only need to move your big toe with one hand and the other to feel the fascia stiffening under the arch of your foot.
Is plantar fascia a muscle?
NO! This is not something you can strengthen!
So, we can agree that this structure has no contractile capacity compared to a muscle. However, the fascia does not do all of its work alone! Of course, many muscle groups come to its support.
To fully understand this, it is the intrinsic and extrinsic muscles of the foot and leg that actively support the arch of the foot and also play an important role in shock absorption.
Bolgla LA, Malone TR. Plantar Fasciitis and the Windlass Mechanism: A Biomechanical Link to Clinical Practice. Journal of Athletic Training. 2004;39(1):77-82.
Fuller, E. A. (2000). The windlass mechanism of the foot. A mechanical model to explain pathology. Journal of the American Podiatric Medical Association, 90(1), 35-46.
Kappel-Bargas, A., Woolf, R. D., Cornwall, M. W., &McPoil, T. G. (1998). The windlass mechanism during normal walking and passive first metatarsal phalangeal joint extension. Clinical Biomechanics, 13(3), 190-194.