An article of footwear has an upper and a sole. The sole has an upper sole
member, a lower sole member, and at least one inflatable bladder disposed
between the upper sole member and the lower sole member. The at least one
inflatable bladder has an inflated state and a deflated state. A distance
between the upper sole member and the lower sole member is greater in the
inflated state than the deflated state. Varying the inflation of the
inflatable bladder varies the amount of cushioning in the sole and the
thickness of the sole so that the shoe can serve as a multipurpose shoe
for activities requiring different amounts of cushioning, such as a
training shoe and a racing flat.