Parents can help make high school football as safe as possible for their children, experts say, by:

*Scheduling their child for a complete physical. This should include cardiovascular stress testing (checking blood pressure and pulse before, immediately following, and 10 minutes after exercising) and checking the musculoskeletal system for loose joints. If loose joints are found, ask for appropriate strengthening exercises.

Making sure water is available during practice and that players are allowed to drink freely. Check you child's weight before and after practice -- if he has lost 10 or more pounds during any given practice, have him begin re-hydrating with water immediately.

*Requesting that, in hot weather, players be allowed to remove helmets, shirts and shoulder pads during breaks in practice or while on the sidelines. This provides maximum skin exposure to air, which allows sweat to evaporate and cool the body.

Checking the player's helmet for proper fit. It shouldn't wobble but should fit snugly against the forehead. The pad at the rear base of the helmet should rest comfortably against the back of the neck.

*Consulting a doctor before allowing your child to play or practice while suffering from a headache. Even a mild, lingering headache may indicate a problem, since a football player can never be sure whether a headache is caused by blows to the head during the sport. Because aspirin promotes bleeding, it should not be taken until a doctor is consulted.

*Encouraging players to wear knee braces to give added support to the joint and prevent injury. A damaged knee is the most common serious injury in football.

*Making sure professional medical personnel such as doctors, trainers or paramedics are present at all practices and games.

The Center for Health and Sports Medicine will provide the names of doctors who specialize in sports-related injuries and rehabilitation. The center also holds an annual sports medicine seminar for coaches in May. For more information, write Center for Health and Sports Medicine, 1577 Spring Hill Rd., Vienna, Va. 22180, or call 553-2460.