Most trainers, like other professionals who work with athletes, were first drawn to sports as participants. High school and college students can gain valuable experience by actively participating in a sport. Such experience lends a prospective trainer added insight into the injuries typical of a given sport, as well as the compassion and empathy necessary to comfort an injured athlete who is forced to sit out a game. Most teams need help with everything from equipment to statistics, so plenty of opportunities exist to explore a variety of sports-related positions. Good experience can be gained by working with and learning beside a trainer or team physician. This type of experience is a helpful foundation for a future internship or job; successful candidates are usually those with the most experience and on-the-job training.

Sports trainers help amateur and professional athletes prevent injuries through proper exercises and conditioning; provide immediate first-aid to injuries when they occur during a practice or event; and lead injured athletes safely through rehabilitation programs and routines. For the most part, sports trainers are not medical doctors, and are not allowed to conduct certain procedures or provide advanced types of medical care, such as prescribing or administering drugs. Some trainers, however, are trained physicians. If an individual is also trained as an osteopathic physician, for example, he or she is licensed as a medical doctor and can conduct more advanced procedures and techniques, including diagnosis, surgery, and the prescription of drugs.

In order to prevent injuries, sports trainers organize team physicals, making certain that each player is examined and evaluated by a physician prior to that athlete's participation in the sport. Along with the team physician, they help to analyze each athlete's overall readiness to play, fitness level, and known or existing weaknesses or injuries. When necessary, they recommend stretching, conditioning, and strengthening exercises to aid the athlete in preventing or exacerbating an injury. This may involve developing specific routines for individual athletes. Finally, athletic trainers work with coaches, and sometimes team physicians, to choose protective athletic equipment. Before games and practice, they often inspect the playing field, surface, or area for any flagrant or subtle risks of injury to the athlete.

Prior to a practice or competition, the athletic trainer may help an athlete conduct special stretching exercises or, as a preventive measure, he or she might tape, wrap, bandage, or brace knees, ankles, or other joints, and areas of the athlete's body that might be at risk for injury. The trainer routinely treats cuts, scratches, and abrasions, among other minor injuries. They may tape, pad, or wrap injuries, and install face guards. When serious injuries do occur, whether in practice or during a competition, the athletic trainer's role is to provide prompt and accurate first-aid treatment to the athlete to ensure that athlete's full recovery. They are trained in emergency procedures and prepared to provide emergency treatment for conditions such as shock, concussion, or bone fracture, stabilizing the athlete until they reach a hospital or trauma center. Often, the trainer will accompany the injured athlete to the hospital, making certain the team physician or an assistant trainer is still on hand to address the health concerns and needs of those athletes who are still competing.

Working in concert with the team physician and several other health professionals, athletic trainers often supervise the therapeutic rehabilitation of athletes under their care. They analyze the athlete's injury and create individualized therapy routines. The trainer may advise the athlete to wear a protective brace or guard to minimize damage while the athlete is recuperating from an injury. Athletic trainers in charge of every level of athlete should be licensed to perform specific medical functions and operate certain devices and equipment.