So here is a paper which confirms the pre-tensioning of the plantar fascia , pre heel strike , by way of activation of the toe extensors (1) P Caravaggi et al 2009 .

In my opinion , and in a counter intuitive twist , this pre-tensioning results in less tension in the plantar fascia during weight acceptance than would otherwise be the case .If you like , it prevents a rapid "tension transient" in the fascia during weight acceptance and ameliorates the potentially damaging effects of high levels of kinetic energy in the tissues of the foot as a whole .

An enlightening paper .

Quote -
"The simultaneous action of the ankle dorsiflexors and toe extensors, which prevent foot-slap and dorsiflex the toes at the MTPJ, and the plantarflexion moment applied to the calcaneus by the vertical ground reaction forces could account for some pre-stretching of the PA. A MTPJ dorsiflexion angle of about 30 deg. was measured for the three subjects thus confirming the action of the toe dorsiflexors at and prior to heel-strike (Table 4).
Indeed, a recent study has proposed that early stance preloading of the PA may be beneficial to propulsion during walking (Pataky et al., 2008). While the present study strongly suggests that such preloading exists, without further experimental and/or modelling studies, we can only speculate as to the possible advantages of such preloading. Loading the PA at heel-strike is likely to reduce the crimp present in unloaded collagenous tissues (Butler et al., 1978), thereby resulting in earlier arch stiffening and helping to ensure that, as the propulsive phase begins, a greater proportion of force is transferred by the foot to the ground."

Paper (1)
A dynamic model of the windlass mechanism of the foot: evidence for ...
by P Caravaggi - ‎2009 - ‎Cited by 60 - ‎Related articles
This is the so-called windlass mechanism which, in the late phase of stance, is responsible for raising the arch of the foot (Hicks, 1954) and contributing to stiffening of the foot by pulling on the heel, causing inversion at the subtalar joint and `locking' the midtarsal joint (Briggs and Tansey, 2001). Previous studies using finite ...

Gerrard Farrell