US-based cardiologist Dr. Dmitry Yaranov has urged people to treat their daily step count as a fifth vital sign, alongside pulse, temperature, and blood pressure. In an Instagram post, he explained that step data reflects both physical and mental health, offering early clues to issues like frailty, depression, or vascular disease. Calling movement "medicine," Dr. Yaranov emphasized that a sudden drop in steps is often the body's first warning sign.