Four years ago this month, 18-year-old Jon Walsh collapsed and died during a mile-and-a-half run on the first day of football practice at Robinson High School in Fairfax. Walsh was a 6-foot-1, 190-pound offensive lineman who had earned varsity letters in both football and wrestling as a junior. His football coach called him "a leader, outgoing, fun-loving, one of the best conditioned athletes we had."

Walsh's death was eventually attributed to a heart disorder that had gone undetected despite a rigorous physical exam earlier in the summer. He was one of seven high school football-related fatalities across the country in 1981. A total of 38 high school athletes have died from football-related incidents since 1980, according to the National Federation of State High Schools Association (NFSHSA).

Last week, 19-year-old Charles Mitchell, a freshman player at Henderson State University in Arkansas, died a couple of hours after he collapsed during a 12-minute run that is part of a physical examination for the players. Mitchell had excelled in high school basketball, baseball and football.

The deaths of such unlikely victims raises concern among doctors, parents and coaches every year at this time as teams practice for the fall season.

While athletes tend to focus on potential glories, coachs and doctors look to preventing, detecting and healing damaged knees, broken bones, contusions and concussions that often go along with the game. More attention than ever is being paid to student athletes' overall conditioning, to practicing and playing in the heat, and to identifying and treating injuries.

The result? "We've been fortunate in recent years in largely avoiding the catastrophic type of injuries," says Otto Jordan, director of athletics for the D.C. Public Schools for the past 14 years. "We've benefited in the last few years from stronger health care and coaches who are quite concerned and capable."

Jordan, who is a member of the rules committee for NFSHSA, also credits stricter enforcement of rules that prohibit "spearing" (hitting with the head first) and "clipping" (blocking from behind) with making the game safer in recent years. "We're always looking for ways to make the game more safe," he says.

One way to make high school football safer, contends Dr. John Albrigo, an Arlington orthopedic surgeon in sports medicine who works closely with a number of local high school athletic programs, is requiring more extensive physical check-ups of players.

"The athlete should have his cardiovascular system checked," Albrigo says, "his musculoskeletal system examined, see if he can touch his toes, check for loose knees, look at his muscle tone."

High school athletic physicals often are provided by the school and performed by a doctor who generally charges a reduced fee for examining a large number of students, says Albrigo. He considers these physicals -- which generally include height, weight, blood pressure, pulse, urinalysis, and an examination of heart and lungs with a stethoscope -- inadequate for someone planning to play football.

"In a cardiovascular examination, blood pressure and pulse should not only be taken at rest, but in a stress situation -- like after running," Albrigo says. "Have him run a mile and then check his pulse and blood pressure immediately after he's finished, then three minutes later check it again, and then again six to 10 minutes later. This way you see what the individual is like prior to excercise, immediately following it, and at rest after excercise."

In examining the musculoskeletal system, Albrigo considers it essential that, in addition to looking for deformities such as curvature of the spine, doctors test and assess muscle tone to help discover loose joints, which might easily be damaged through contact on a football field. If detected early enough, he says, loose joints can be strengthened through a careful exercise program, allowing the youngster to play with less chance of injury.

Many coaches and trainers run prospective players through strength and endurance tests periodically throughout the school year. The tests include weight-lifting exercises, such as the bench press, leg press and arm curl, and cardiovascular endurance tests, such as seeing how far a candidate can run in 12 minutes or by timing him in a 600-yard run or a series of shorter sprints.

"These tests give us a regular indication of their fitness levels," says Larry Nottingham, trainer at Robinson High School. "Most of the kids follow the program so they'll be in good shape when practices begin. But if they're really out of shape, we don't even give them any equipment."

If disparities show up in an athlete's height, weight and strength, he may be put on a program to correct the problem before he is allowed to practice with the team, says Nancy Burke, an athletic trainer at South Lakes High School in Reston. For example, if a candidate is overweight and lacks the leg strength needed to make certain movements on the football field, he might be required to build up his legs before being allowed to play. Burke also examines players to determine if they need special equipment. "If a player has a long neck, he might be prone to whiplash," she says, "so we'll get him a neck collar" -- a horseshoe-shaped pad that surrounds and cushions the neck.

In recent years, high school football practices have changed considerably from the stoic and spartan-like setting of a decade or two ago. Many coaches, aware of the dangers of heat and muscle fatigue, encourage players to drink water freely during practice and schedule five minute rest breaks for every 25 or 30 minutes of practice, depending on heat, humidity and intensity of the drills. Coaches also encourage players to take periodic checks of their own pulse, forcing them to sit out drills if their pulse rate is too high.

Heat is a primary concern, especially in preseason workouts. Three of the seven high school football fatalities in the country last year were heat-related, according to NFSHSA.

At Robinson, Nottingham travels around the practice field on a golf cart to keep a supply of ice on the field and to transport injured players who might need to return to the training room for treatment. Nottingham also carries a two-way radio so, in case of an emergency, he can make immediate contact with the school's main office.

There are, however, some coaches who "even to this day are reluctant to allow for abundant fluid replacement," Albrigo says. "There is simply no substitute for water. It should be on the field at all times."

Players should weigh themselves before and after each practice to check on their water loss, advises Melanie Calitri, a physical therapist with the Center for Sports Medicine in Vienna, Va. It is not unusual for a player to lose several pounds of water during a practice, but Calitri advises any player who loses 10 or more pounds to "take water right away." Calitri recommends water rather than beverages that claim to replace electrolytes and minerals because "water doesn't have to be digested; its effect is immediate."

During breaks in practice players should "seek maximum skin exposure to air so sweat evaporates" and cools them off, Albrigo says. Calitri advises players to take off their helmets "whenever possible" because uncovering the head "allows body heat to escape."

Nottingham teaches Robinson players how to check their pulse, a team requirement when doing any kind of running. A player whose pulse is too fast is not allowed to run until the rate drops.

"If a player's heart rate is consistently up, then it indicates that he's working too hard," Nottingham says. "We want to keep an eye on that. Between sprints, we like to see the pulse get down to 120 or 130 beats per minute after a minute or two rest -- that's still good for aerobic conditioning. The biggest problem is that kids are likely to say their pulse is down when it's not."

As high school players increase their strength, speed and size, they also increase the potential for injury.

The daily barrage of sprains and strains is handled routinely by players, coaches and trainers.

"The first things you check for are swelling and loss of mobility," Burke says. "If he has either of those, he's out of the practice or game . We ice it down to reduce the swelling. If there's no problem with range of motion, we might just wrap him up to make sure and then let him continue working out." But, she adds, "Trainers are a conservative group; we can't take a chance with somebody. When a player goes back out, he must be ready to play. If there's a question, they don't play."

The most common of the more serious football injuries, according to Albrigo, is damage to the anterior cruciatic ligament which supports the knee. The injury is often misdiagnosed as a sprain by trainers or emergency room personnel, who "give the kid a splint and a crutch and tell him to see a doctor in a couple of days," Albrigo says. "It's the first thing orthopedic surgeons look for on a knee exam, it's so common."

Depending on the extent of the damage, surgery may be required. But Albrigo says knee injuries could be curtailed by using either the Anderson or McDavid knee brace, which are both designed to give the knee extra support on contact without limiting a player's flexibility or speed.

"I think it's more important than shoulder pads," Albrigo says, "because the knee is so exposed. Coaches can talk themselves out of using the brace for their players because they say it puts their players at a disadvantage since they think it reduces their speed. The way around that is to make it part of the required equipment for everybody."