How Inactivity Impacts Bone Strength

young boy on couch with iPad


Usually, when parents think about their child's health, they do not consider their bone health. Instead, they think about how they are growing, their annual health checkups, and maybe even their diet. But building healthy bones now, while they are still growing, is an important consideration. Not only does good bone health prevent fractures and add strength, but it also can help prevent osteoporosis later in life.

A Closer Look at Osteoporosis

Osteoporosis is a disease where, as a person ages, their bones become less dense and more prone to fractures. What's more, it is sometimes referred to as the childhood disease that comes with consequences in old age. The reason is simple. The bone mass a person attains in childhood and throughout the teens years helps determine their lifelong bone health. Without good health habits and adequate physical activity now, their bones will break as they age.

When children are young, their bodies make new bone faster than it breaks down old bone. So, their bone mass increases. Most people reach their peak bone mass around age 20 and up to age 30. At that point, bones have reached their maximum strength and density. In fact, up to 90 percent of peak bone mass is acquired by age 18 for girls and age 20 for boys. After that, bone remodeling continues, but you lose slightly more bone mass than you gain.

The likelihood of your child developing osteoporosis later in life depends on how much bone mass they attain by the time they reach age 30, as well as how rapidly they lose it after that.

The higher their peak bone mass, the more bone they will have stored and the less likely they are to develop osteoporosis as they age.

Why Healthy Bones Are Important

When a person has strong bones, they are well-supported and able to move easily. What's more, strong bones protect our heart, lungs, and brain from injury. Our bones also store the vitamins and minerals that we need. Meanwhile, weak bones break easily, can cause intense pain and may even result in a reduction in height.

Keep in mind that your child's bones are living organs. They have cells and are flowing with body fluids. What's more, bones are constantly growing and renewing. As a result, they can grow stronger with a good diet and physical exercise.

Additionally, when your kids run, jump or lift something heavy, this puts stress on their bones. This stress, in turn, sends a signal to their brain that their bones need to be made stronger. In response, new cells are added to strengthen your child's bones. For this reason, parents need to encourage their kids to run, jump and play. Doing so, helps them invest in their bone health.

Physical Activity and Healthy Bones

Most parents believe that once teens reach their full height, they are done developing. But the truth is, the late teen years are a vital time for bone growth, even after a teen is fully grown. In fact, a study published in the JAMA Pediatrics found that roughly 10 percent of bone mass continues to accumulate after teens reach their adult height.

The study also found that bone growth develops at different rates in various parts of the skeleton and that height growth far outpaces bone growth before adolescence. These findings could help explain why children and teens have high fracture rates. Between 30 and 50 percent of children and teens will have at least one broken bone before adulthood.

Meanwhile, another study measured physical activity and bone strength of 309 teenagers over a four-year period. The study's four-year window included girls ages 10 to 14 and boys ages 12 to 16. This time period is vital because as much as 36 percent of the human skeleton is formed and bone is particularly responsive to physical activity.

What they discovered is that teens who are less active had weaker bones. In other words, kids who are sitting around gaming, using technology or just being lazy are not loading their bones in ways that promote bone strength, the study's authors say. Some examples of weight-bearing activities include running and jumping or sports like soccer, basketball, volleyball, and ultimate Frisbee.

What's more, even though boys had larger and stronger bones throughout the study, both boys and girls responded the same way to physical activity. Additionally, researchers note that the type of physical activity does not have to be structured or organized sports to be effective. In fact, short bursts of activity like dancing around the house, chasing the dog, or skipping also have a positive impact on bone health.

Ultimately, the key to strong bones is to put down the technology and limit screen time in favor of more physical activities. Even going for a walk can promote healthy bones.

Factors Impacting Bone Health

Bones are continuously changing, especially in children and teens. In fact, new bone is being made and old bone is being broken down. Consequently, a number of things can impact this process. Here is an overview of some of the factors that impact bone health and strength.

Physical Activity. As mentioned earlier, children and teens who are physically inactive have a higher risk of osteoporosis later in life than their more active peers.

Calcium Intake. When a young person's diet is low in calcium, this results in diminished bone density. It also can lead to an increased risk of fractures and early bone loss.

Eating Disorders. Teens that have eating disorders such as anorexia or bulimia are at risk for bone loss. What's more, Crohn's disease and celiac disease also can impact the body's ability to absorb calcium.

Certain Medications. Talk to your doctor about the medications your child is taking and their potential impact on bone health. For instance, long-term use of prednisone can be damaging to your child's bones.

Race and Gender. Typically, white and Asian women are at the greatest risk for osteoporosis. What's more, having a family member with the condition also puts your child at a greater risk. Make sure you are taking steps to build bone health.

How to Keep Your Kids' Bones Healthy

Developing healthy habits like proper nutrition and physical activity will go a long way in promoting bone health in your kids. Remember, your kids are watching you closely. So, your habits, both good and bad, have a strong impact on their behavior.

The best way to encourage healthy habits in your kids is to first be a good role model yourself.

Diet and Exercise Are Key

The best thing you can do is to encourage proper nutrition and plenty of physical activity. You can do this by preparing healthy meals and snacks and limiting screen time. You also may want to get them involved in extracurricular activities as well as encourage them to do other physical activities like playing tag, walking the dog, and ice skating.

When preparing meals, be sure to include plenty of foods that are rich in calcium and vitamin D. In fact, most kids do not get enough calcium in their diets to help ensure optimal peak bone mass. For instance, one 8-ounce glass of milk provides about 300 milligrams of calcium which is only about one-fourth of the recommended intake for teens. For kids who will not drink milk, try cheeses, yogurt, calcium-fortified juices, and cereals, as well as green leafy vegetables. If you are concerned about your child's calcium intake, talk to your doctor about supplements.

You also should talk to your kids about their bone health and how they can invest in their bones now. Discuss the importance of diet and exercise. Aside from getting adequate amounts of calcium and vitamin D, your teens should be exercising a minimum of one hour per day. This could mean skateboarding, dancing, participating in sports, walking, or running. What's more, the hour spent exercising does not have to be consecutive. In other words, skateboarding for 20 minutes, walking for 20 minutes, and dancing for 20 minutes counts too.

Meanwhile, over-exercising, especially combined with restrictive dieting, also puts bone health at risk. If your teen is training more than is recommended or seems prone to over-use injuries, you may want to re-evaluate what they are doing. Talk to their doctor about your concerns and see if cutting back on the physical activity is recommended.

Make a point to talk to your kids about risks to their bone health like smoking, vaping, drinking and drugs.

Research suggests that tobacco use results in weak bones. Likewise, drinking consistently also has been linked to an increased risk for osteoporosis. These risk factors are yet another reason why kids should avoid these substances.

A Word From Verywell

Remember, building strong bones begins in childhood. With healthy eating habits, consistent physical activity, and regular visits to the doctor, your kids can have strong bones throughout their lives. The key is getting enough calcium, vitamin D, and physical exercise. Combining these factors on a consistent basis will result in stronger bones and better overall health.

Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  • "Association Between Linear Growth and Bone Accrual in a Diverse Cohort of Children and Adolescents." JAMA Pediatrics, September 5, 2017.

  • "Kids and Their Bones: A Guide for Parents." National Institute of Health, 2018.

  • Leigh Gabel, Heather M Macdonald, Lindsay Nettlefold, Heather A McKay. "Physical Activity, Sedentary Time, and Bone Strength From Childhood to Early Adulthood: A Mixed Longitudinal HR-pQCT Study." Journal of Bone and Mineral Research, 2017.

By Sherri Gordon
Sherri Gordon, CLC is a published author, certified professional life coach, and bullying prevention expert.