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8th grade physical health guide: Find out what you need to know

Here's what you need to know about your eighth-grader's physical health.
Two teenage girls having fun outdoors
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During eighth grade, children are typically going through puberty and experiencing the rapid and profound changes that take place as they mature into adults. Although they have been growing throughout their young lives, during adolescence their bodies grow more quickly than ever, especially during the phase known as the adolescent growth spurt, from around the age of nine until the end of puberty. They are also experiencing dramatic and exciting psychological changes as they make the transition from childhood to adulthood. Children in eighth grade are usually 13 or 14 years old, and the physical health guide below covers adolescents in this age group. However, if you are concerned about your child’s physical development, you should consult your pediatrician or family physician.

Physical activity


Engaging in regular physical activity and exercise is essential for adolescents. It promotes growth, helps them build strength and develop healthy bodies, and can even enhance academic performance. Regular physical activity also reduces the risk of obesity and chronic diseases, such as diabetes, cardiovascular disease, and certain cancers. Many children become less physically active with the onset of puberty, increasing their risk of developing conditions such as diabetes and obesity. Regular physical activity and exercise can help adolescents feel in control of their bodies and can also be a helpful way of dealing with the stress and emotional changes that occur during puberty.


The benefits to your child of physical activity can include:

  • Increased self-sufficiency and confidence
  • Improvements in learning
  • Better sleep
  • Weight management
  • Stress management
  • Improved social skills
  • Decreased risk for chronic diseases later in life
  • Decreased television, video game, cellphone, and computer use


The U.S. Department of Health and Human Services recommends that children and adolescents participate in at least 60 minutes of vigorous or moderate-intensity physical activity each day. This does not need to be 60 minutes of sustained activity at a time, but can include different episodes of activity that, together, total 60 minutes or more. Adolescents should take part in a variety of activities that require different degrees of exertion. These should include vigorous activities, such as running, and more moderate activities, such as brisk walking.

Maintaining healthy habits

The proportion of young people who meet the recommended guidelines for physical activity declines as children age, and adolescents are often likely to become less active as they get older. This decline comes just as maintaining a healthy level of physical activity becomes more important than ever, as children mature into their adult bodies. Research has found that the number of fat cells in our bodies is set during adolescence, and although these cells can shrink or expand later in life, they cannot be eliminated. Establishing and maintaining healthy physical activity habits at this age will help set adolescent bodies on a path to lifelong fitness and well-being.

Weekly activity

The guidelines recommend that children and adolescents engage in vigorous physical activity at least three times a week. This can include playing soccer, doing martial arts, or riding a bike.

Building muscle

Building muscle strength is especially important for children and adolescents, and exercise is key to achieving this goal. Muscle-strengthening activities are those that force the muscles to do more than the normal workload and should include all the major muscle groups of the body. Examples of muscle-strengthening activities include climbing, sit-ups, and resistance exercises. The guidelines recommend that children and adolescents engage in muscle-strengthening activities at least three times a week.

Bone strength

Adolescence is a crucial time for building bone mass, up to a quarter of which is formed during the adolescent growth spurt, from around the age of 9 until the end of puberty. Bone-strengthening exercises build strength through the force that is exerted on the bones. Activities that achieve this important goal include jumping, running, skipping rope, and playing tennis or volleyball. The guidelines recommend that adolescents engage in bone-strengthening activities at least three times a week.


Sleep overview

As your child ages and the demands of school, socializing, and extracurricular activities increase, your ability to convince your teenager to prioritize sleep may be difficult. It is important for you to continue to talk with your child about their sleeping habits and lay out clear expectations around sleep. Most middle school students sleep far less than experts recommend and are actually sleep-deprived. According to the National Sleep Foundation, only 15% of teenagers reported sleeping at least 8 ½ hours on school nights. Sleep deprivation distracts students from focusing in school, increases the likelihood of acne, and increases the likelihood of gaining weight. In addition, it can lead to a higher risk for heart attacks, strokes, or type 2 diabetes later in life. It is important for you to keep track of your child’s sleeping habits as your child ages. If you notice significant changes, it may be a sign that other health-related issues are present. Consult with your child’s health care provider about additional steps you can take to ensure your child gets a more restful night of sleep.

Nightly sleep needs

Despite the strains on your child’s time, students in eighth grade should sleep for approximately 9 hours and 15 minutes every night. To achieve this goal, a student who needs to be up by 6:15 a.m. to get ready for school should be in bed no later than 9 p.m. Though a 9 p.m. bedtime may seem unattainable to some, experts recommend making sleep a priority by encouraging your child to get as much sleep as possible. The closer they are to getting the recommended amount of sleep, the better.

Learn more about supporting your child with our eighth grade physical health tips page.

Parent Toolkit resources were developed by NBC News Learn with the help of subject-matter experts, including Dr. Natasha Burgert, Pediatrician, Pediatric Associates and Dr. Jayne Greenberg, District Director, Miami-Dade County Public Schools.