Downstairs stepped on the air twisted to the foot now walking are painful to consider for muscle strain, ankle sprain and other reasons. 1. Muscle strain: Strong and rapid contraction or overstretching of the muscle will exceed the tolerance of the muscle tissue, resulting in muscle tear or rupture, known as muscle strain. The main manifestations are muscle pain, bruises, ecchymosis or swelling of the skin, and restricted movement of the injured area. When the symptoms are mild, the strained muscle will be a little stiff and spasmodic, and when the symptoms are severe, you may not be able to move. 2. Ankle sprain: stepping down stairs and twisting your foot now hurts when you walk. It can be caused by activities that exceed the normal mobility of the ankle joint, which results in damage to the ligaments, joint capsule and other soft tissues around the ankle joint. In mild sprains, the ankle joint is lightly swollen, there are pressure points, aggravated by activity; moderate sprains, pain is more intense, swelling is more serious, can be accompanied by obvious subcutaneous ecchymosis. Downstairs stepped on the air twisted to the foot now walking pain may also be fracture and other causes, it is recommended to seek medical attention to clarify the diagnosis, under the guidance of the doctor for targeted treatment.