Think of your bones as a bank. Strong bones in childhood are a good start for bone health throughout life. Every deposit you make now is saved up for later, so it is worth knowing how the deposits are made.
Bone is not like a stone, because it is living tissue, and old bits of bone are removed and replaced with new bone all the time. That means your bones are hard at work right now, while you read this. So how do you build good bone? Three things build healthy bones: calcium, vitamin D, and exercise. Let's take them one at a time, starting with the first two.
Calcium is a mineral that helps build strong bones, and milk, yogurt and cheese are among the best food sources of calcium. Leafy green vegetables, such as kale and collard greens, also have it. Vitamin D helps the body take in the calcium it gets from food, so the two work as a team. Kids need healthy food every day to grow, and a good plate has half vegetables and fruits.
The third thing is exercise. Running, jumping and playing make muscles and bones stronger. Hopping, skipping, jumping and running all strengthen bone, and kids should do bone-strengthening and muscle-strengthening activities at least 3 days a week. Younger children strengthen their muscles with gymnastics, jungle gyms and climbing trees. Most children do not need weightlifting programs.
How much active play is enough? As of November 2026, kids 6 to 17 years old need at least 60 minutes of active play or exercise every day. Those 60 minutes do not have to come all at once, since walks, jump rope and playground time add up. For ages 3 to 5, active play is the best exercise, and they should be active throughout the day for growth and development.
Now, how do bones get longer? Long bones are the bones that are longer than they are wide, such as the thighbone, the forearm bones and the bones of the hands. A long bone does not grow from its middle outward. It grows at each end, next to a growth plate.
Most long bones have two growth plates, one near each end. A growth plate is made of cartilage, a rubbery, flexible material. Growth plates are the places where bones make new bone, so the bones can grow longer.
A growth plate is weaker than solid bone, so it is easier to injure. Growing does not last forever, either. When a person is fully grown, the growth plates harden into solid bone. After a growth plate has closed, that bone is no longer growing longer.
What decides how a child grows? Genes have a large say, and children in a family often grow in similar patterns. Yet nobody grows at a perfectly steady rate. Kids grow in spurts, with faster stretches and slower stretches, and each child grows at their own pace. Rest matters too, because sleep helps kids grow and growing bodies need the rest. As of November 2026, kids 6 to 12 years old need 9 to 12 hours of sleep in every 24 hours. In deep sleep, the body releases hormones that kids need for growth and development. A school-age child who does not get enough sleep can have trouble paying attention.
So here is the bone bank in one idea. The bone you build as a kid helps your bones for the rest of your life, because the most bone you will ever have is built when you are young. Calcium, vitamin D and active play are the deposits, and they all add up.
Words to know
- cartilage: rubbery body stuff
- genes: body instructions
- spurts: quick bursts
