Arteriosclerosis obliterans (ASO) is a slow build-up of plaque inside the arteries that feed your legs. Think of it as a traffic jam that lets less and less blood through, so leg muscles scream for oxygen whenever you walk.

Cramping calf pain is the classic red flag. It hits after a block or two of walking and forces you to stop until the ache fades.

Numb or heavy legs follow. Your thighs or calves feel like they’re filled with wet sand, especially after exercise.

Cold feet show up early. One foot feels cooler than the other, and socks never seem warm enough.

Color changes appear. The foot turns pale when elevated and dusky red when hanging down.

Hair loss and shiny skin occur. Lower-leg hair thins, and the skin looks tight and glossy because blood flow is poor.

Late alarms include foot pain at rest, ulcers that won’t heal, or black toes—signs the artery is nearly blocked.