Anatomy, physiology, and biochemistry are complementary basic medical sciences studied together in medical science and human performance. In real time, anatomy and biomechanics are the basis of injury prevention and improving performance in sports and work. Excellence in athletics and work performance depends on understanding the relationship of an athlete's specific anatomy as advantage or disadvantage in particular sports or line of work. For example, size and weight are better for a linebacker than a quarterback. Less obvious is shoulder flexibility, which is usually better for baseball pitchers, but not as helpful for a boxer. Why? Because a flexible shoulder allows greater range of motion -- promoting faster angular velocity of the arm, and greater speed of the baseball. A tighter shoulder with less range of motion may transmit force in a punch better -- from the boxer's ground reaction force at the feet, to the core, to the arm and punch.