It’s never too soon to instill a love of physical activity in kids by exposing them to fun fitness activities and sports. Pediatric experts say that participating in different activities develops a variety of motor skills and muscles, and, most importantly, it reduces the risk of developing overuse injuries. A recent American Academy of Pediatrics (AAP) report on child and adolescent sports-related injuries suggested that children are better off playing a variety of competitive sports to supplement, not replace, free play and recreational sports (where the goal is participation and fitness, and not competition) at least until puberty.

Here are some guidelines to help you choose age-appropriate fitness activities for your kids.

Age 5 and younger

Preschoolers can play team sports such as soccer, basketball, or T–ball as long as your expectations are realistic: Any sport at this age should be about play, not competition. (Anyway, most five-year-old children aren’t coordinated enough to hit a pitched ball and don’t have true ball handling skills on the soccer field or basketball court.)

Preschoolers tend to love water, and it’s fine to introduce kids to water safety between six months and three years old. The American Red Cross, the country’s leading water safety and instruction organization, recommends that preschoolers and their parents first enroll in a basic course that teaches blowing bubbles and underwater exploration before starting formal swimming lessons. Starting at about age four or five, children are ready to learn breath control, floating, and basic strokes.

Ages 6–8

By age six, children have made developmental leaps that make it possible for them to hit a pitched baseball and pass a soccer ball or basketball. They can also do complicated gymnastics routines and confidently pedal and steer a two-wheeled bike. Now is the time to expose children to diverse athletic and fitness-related activities because different sports stress growth plates differently, and the variety helps ensure healthy all-over development. Overuse injuries, such as stress fractures, so-called Little League Elbow, and heel pain in soccer players, are increasingly common and happen when kids play the same sport season after season.

Ages 9–11

Eye-hand coordination really kicks in at this point, so children are usually able to hit and accurately throw a baseball and make solid contact with a golf or tennis ball. It’s okay to encourage competition—as long as you don’t put all the focus on winning. If children are interested in participating in events such as short triathlons or 10K distance running races, these are safe as long as children have trained for the event and maintain healthy hydration (which parents must monitor). 

Ages 12–14

Unless your child has gone through puberty, discourage lifting heavy weights. Encourage healthier options such as using stretchy tubes and bands and doing body-weight exercises such as squats and pushups. These develop strength without endangering bones and joints. Prepubescent kids should never attempt a one-rep max in the weight room. During periods of rapid growth, such as those experienced during the early teenage years, children are at the biggest risk for injury. A child who lifts too much weight or uses poor form when throwing or running at max effort can break bones.

Age 15 and older

Once your teen has gone through puberty and is ready to pump iron, you should urge him or her to take a weight-training class or invest in a few sessions with an expert. Poor form can harm muscles and cause fractures.           

If your high schooler expresses interest in endurance events—such as triathlons or marathons—there’s no reason to say no. Just keep an eye on nutrition (teens need extra calories) and hydration, and learn to recognize the signs of heat-related illness. Remember that proper training is just as important for teens as it is for their parents. Many races have minimum age requirements, usually 16 or 18.