A generation or so ago, spring sports meant baseball and softball and track. Today, young athletes look forward to warm-weather opportunities in those sports, plus soccer, lacrosse, tennis, roller hockey and more.
The trend goes virtually year-round, with potentially elite athletes either playing or training to play one or more sports all the time with more indoor facilities opening for practice.
While the broader smorgasbord of sports gives more teens a chance to play and encourages fitness, it also puts them at increased risk for injury, both from contact and from excessive strain on arms and legs.
"These days, it seems in order to be a well-rounded student and gain admission to a good college, participating in at least one or even two extracurricular sports is on almost every student's to-do list," said Col. Tom DeBernardino, the sports-medicine fellowship director at the Army hospital serving the U.S. Military Academy at West Point.
"However, increased exposure to sporting activities translates into increased risk of injuries sustained by these young student athletes," he added.
All of the 4,000 cadets at West Point are required to take part in organized sports and other physical activity along with military training.
But DeBernardino, discussing sports-injury trends during a meeting of the American Academy of Orthopedic Surgeons in San Francisco last week, noted a disturbing trend among the first-year cadets.
Among the plebes this year, at least 50 already had reconstructive shoulder surgery before arriving at the academy; in 1998, fewer than a dozen had undergone such surgery.
It's estimated that 30 million to 45 million American teens between the ages of 6 and 18 (out of a school-age population of about 53 million) take part in some type of athletics.
While comprehensive stats are hard to find, various studies published in recent years suggest that up to a quarter of those youngsters get injured, and that at least half of those injuries are from overuse or overtraining.
Pediatricians and orthopedic specialists say they're seeing the sorts of injuries in teens, even some preteens, that once were reserved for older, more advanced athletes -- damage to knee and elbow ligaments and tendons, shoulder-muscle tears, along with injuries created by excessive wear and tear to cartilage and growth plates near the end of young bones.
The experts don't want to stop healthy activity, but the American Academy of Pediatrics has expressed official concern about excessive training, and a clinical special report published last summer suggested that athletes take at least one or two days off per week from competition and sport-specific training and that athletes who play one sport year-round take two or three months off from that specific sport each year.
What about the school-aged teens who don't take part in any sports other than maybe a couple of hours a week of PE at school?
Inactivity, coupled with poor nutrition, puts children at greater risk for obesity. But those who are overweight often tend to avoid competitive sports.
Researchers at Stanford University's School of Medicine tried a little experiment with a group of 21 overweight fourth- and fifth-graders, including 14 who had never been on a sports team.
Nine of the youngsters were assigned to join a soccer team that met three days a week after school. The rest went to a weekly class that taught the importance of healthy nutrition and exercise.
After six months, all nine soccer players had reduced their body mass index, but only five of the 12 classroom participants did so. And many of the teens who played soccer went on to join other regular after-school sports teams playing things like flag football, soccer or tennis.
Dr. Dana Weinstein, lead author of the study published in the Archives of Pediatrics and Adolescent Medicine, said playing with teens of similar weight gave the soccer players more confidence and enjoyment, but that having activities at hand right after school also made it safe and easy for the youngsters to take part.
"Just telling these kids they need to exercise more isn't enough," Weinstein said. "They need positive, supportive opportunities to do so."