This study investigates whether walking or running prevents the formation of edema in the lower leg. In 18 volunteers changes in calf volume were measured using strain gauge plethysmography during slow (3 km/h) and fast (6 km/h) walking or running (10 km/h) on a treadmill for 20 min each. Venous pressure was measured in a superficial vein near the ankle. Low-pass filtering removed motion artifacts from the signals. Slow walking reduced the calf volume in a biphasic manner: a rapid decrease was followed by a slow decline, lasting from about minute 2 to minute 20, its mean rate being -0.073%/min. Besides a rapid initial decrease, no significant change was observed during fast walking. During running, the calf volume first increased within 7 min to a maximum of 2.5% and subsequently decreased with a mean rate of -0.096%/min. The medians of venous pressure were 84.0, 23.5, 30.4, and 29.5 mmHg during quiet standing, slow and fast walking, and running, respectively. The experimental results prove the hypothesis that walking prevents dependent edema formation. This effect, however, cannot be fully explained by the lowered venous pressures.