Foot-Flexor devices aim to secure the foot in a dorsiflexed position during sprint training and are attached around the sprint shoe to the ankle. The theory behind this form of sports bondage is that it encourages sprinters to run with their toes up rather than down, which contradicts the older coaching wisdom that sprinters should run high on their toes. Proponents of dorsiflexed sprinting believe that it maximises force return from the running surface, thus enhancing forward locomotion. A toe-down position is seen to ‘break’ the sprinting motion because the lower limbs will yield as the feet strike the ground, no matter how strong the athlete’s calf muscles.

The devices themselves may be somewhat overrated, but the dorsi-flexed foot position is not; you really do get a feeling of greater power return from the track while running toes up, and the foot has to be ‘coming back toward you’ to optimise push off. However, concentrated toes-up sprinting needs to be gradually introduced into an athlete’s training programme to avoid injury.