A method of countering the effects of G-forces on a person comprises passing inflation gas to a bladder (41, 40) around a leg of the person by starting the inflation of the bladder (41, 49) to an operating pressure from a point (62a, 62d) adjacent an ankle of the leg as well as from a point (62b, 62c, 62e, 62f) spaced from said ankle towards the abdomen of the wearer. The inflation then progresses away from the ankle at the same time as the upper part of the bladder is being inflated. When the bladder (41, 49) is inflated to the operating pressure, the blood vessels of the leg are constricted.