Abstract: An article of footwear having a support structure in the form of a boot (10) a primary lever (22) being pivotally mounted adjacent the heel of the boot (10), the primary lever (22) extending downwardly below the sole formation (17) of the boot (10) and being biased away therefrom, by resilient means (38), and a secondary lever (26) being pivotally mounted adjacent the lower end of the primary lever (22) and being biased away from the sole formation (17) of the boot (10) by resilient means (34), the secondary lever (26) being pivotal relative to the first lever (22) towards the sole formation (17) against the biasing force of the resilient means (34), so that upon downward movement of the boot (10) the resilient means will be resiliently deformed storing energy which will assist motion of the boot in the upward direction.