An internist or Internal Medicine doctor is someone who specializes in diagnosing and treating illnesses, diseases, and health problems. Most internists are also primary care doctors and treat patients on a regular basis. They can diagnose and treat common illnesses or more serious problems. Most people see an internist regularly. Those with chronic illnesses may do so on a monthly or even weekly basis. Internists are the most common types of doctors.

Sports medicine is a branch of medicine that works with athletes and others who play sports or take part in physically demanding activities that may result in injury or other overuse-related problems. Therefore, it is closely related to physical therapy. Since athletes can experience certain issues that may be uncommon in the rest of the population, the doctors who specialize in this field have advanced knowledge of the body and issues that may arise from participating in various physical activities.