Until we can obtain large samples of coronal transverse ground reaction force curves, we cannot draw firm conclusions. We suggest, however, that theoretically such a scheme of variability in mid- and forefoot pressure might reflect a biomechanical function for controlling perturbations in balance in late stance in the coronal plane, through internal/external foot rotation. It is further possible that variability in mid- and forefoot pressure relates to the mechanical influence of a tunable gearing ratio within the foot : that is, the changing relative lengths of the muscle lever arm, and the load lever arm measured from the centre of pressure. Pre-tensioning, the effect of dorsiflexion at the talocrural joint on the plantar aponeurosis (PA) prior to heel strike , followed by a stretching of the PA around the metatarsal heads during toe-off (the windlass mechanism) , contributes to increased stiffening of the plantar soft tissues, and thus, increases the gear ratio at late stance : when the centre of mass is over the forefoot. Hypothetically, it may be possible that the combined variation in gearing  and local stiffness —with a potentially substantial contribution of varying tension of the transverse and oblique heads of abductor hallucis —could contribute to the observed step-to-step variation in forefoot peak pressure, and to the extent to which medio-lateral transfer of pressure in late stance is achieved  (figure 4).