When most adults think about exercise, they imagine working out in the gym, running on a treadmill, or lifting weights.

But for kids, exercise means playing and being physically active. Kids exercise when they have gym class at school, during recess, at dance class or soccer practice, while riding bikes, or when playing tag.

The Many Benefits of Exercise

Everyone can benefit from regular exercise. Active kids will have:

• stronger muscles and bones
• leaner bodies
• less risk of becoming overweight
• a lower chance of getting type 2 diabetes
• lower blood pressure and blood cholesterol levels
• a better outlook on life

Besides enjoying the health benefits of regular exercise, fit kids sleep better. Exercise improves school performance and makes kids less likely to develop depression. Kids who exercise regularly are also better able to handle physical and emotional challenges — from running to catch a bus to studying for a test.

The 3 Elements of Fitness

If you've ever watched kids on a playground, you've seen the 3 elements of fitness in action when they:

1. run away from the kid who's "it" (endurance)
2. cross the monkey bars (strength)
3. bend down to tie their shoes (flexibility)

Parents should encourage their kids to do a variety of activities so that they can work on all these.

Endurance develops when kids regularly get activity. During aerobic exercise, large muscles are moving, the heart beats faster, and a person breathes harder. Aerobic activity strengthens the heart and improves the body's ability to deliver oxygen to all its cells.

Aerobic exercise can be fun for both adults and kids. Aerobic activities include:

• basketball
• bicycling
• ice skating
• inline skating
• soccer
• swimming
• tennis
• walking
• jogging
• running

Improving strength doesn't have to mean lifting weights. Instead, kids can do push-ups, stomach crunches, pull-ups, and other exercises to help tone and strengthen muscles. They also improve their strength when they climb, do a handstand, or wrestle. Muscle strengthening and aerobic exercises like running, jumping, and hopping, also help build strong bones.

Stretching exercises help improve flexibility, allowing muscles and joints to bend and move easily through their full range of motion. Kids get chances every day to stretch when they reach for a toy, practice a split, or do a cartwheel. Dance, yoga, and martial arts, like karate, are examples of flexibility activities.

The Sedentary Problem

Kids and teens sit around a lot more than they used to. They spend hours every day in front of screens (TVs, smartphones, computers, tablets, and gaming systems). Too much screen time and not enough physical activity can add up to unwanted weight gain.

One of the best ways to get kids to be more active is to limit the amount of time spent in sedentary activities, especially watching TV and using phones. The American Academy of Pediatrics (AAP) recommends that parents:

• Put limits on the time spent using media, which includes TV, social media, and video games. Media should not take the place of getting enough sleep and being active.
• Limit screen time to 1 hour a day or less for children 2 to 5 years old.
• Discourage any screen time, except video-chatting, for kids younger than 18 months.
• Choose high-quality programming and watch it with your kids to help them understand what they're seeing.
• Keep TVs, computers, tablets, phones, and video games out of children's bedrooms.
• Turn off screens during mealtimes.

How Much Exercise Is Enough?

Parents and caregivers can help ensure that kids are active every day. In its Physical Activity Guidelines for Americans, the U.S. Department of Health and Human Services recommends:

• for school-age kids and teens (6 through 17 years): 60 minutes or more of moderate to vigorous physical activity daily. This should include muscle-strengthening and bone-strengthening activities at least 3 days a week.
• for preschoolers:active playing throughout the day. A set amount of time hasn't been well defined, but a reasonable target could be 3 hours each day of light, moderate, and vigorous activities. These should include unstructured active free play and planned, adult-led physical activity.

Children under age 3 were not included in these guidelines, but exercise guidelines from Canada, Australia, and the United Kingdom recommend toddlers be active at least 3 hours throughout the day. This should include light activity, active play, and energetic movement, like hopping, running, and jumping.

Young children should not be inactive for long periods of time — no more than 1 hour unless they're sleeping. And school-age kids should not be inactive for periods longer than 2 hours.

Raising Fit Kids

To help keep kids fit and active:

• Help your kids do a variety of fun age-appropriate activities.
• Set a regular schedule for physical activity.
• Make being active a part of daily life, like taking the stairs instead of the elevator.
• Embrace a healthier lifestyle yourself, so you'll be a good role model for your family.
• Be active together as a family.
• Keep it fun, so your kids will come back for more.