Well first they need to have a degree in medicine. They also should have been recommended by at least 3 people.
Answer:
Running
Explanation:
Running is an aerobic exercise that improves your heart and lung function, but only minimally strengthens your bones. While exercise is necessary for bone health, bone has specific needs when it comes to working out. Exercise to build bone strength must surprise the skeletal system with new and varied movements and increased loads. Repetitive exercises like running and walking may actually cause your bones to break down.
