There are many myths regarding exercise floating around the internet and healthcare. One of the biggest ones is children should not lift weights. One of the primary concerns is lifting weights will stunt a child's growth.
The latest research questions that assumption.
One research review article pooled the results of 16 studies — including 1008 children age 7–12 years old — and found weight training had no impact on a child’s height. Studies do show, however, reduced fat mass, improved cardiovascular and metabolic health, and greater bone mineral density.
Research is clear that resistance training is safe and effective for children and adolescents. That doesn’t mean open up the weight room and see what happens. Resistance training should be supervised— preferably by a trained professional such as a strength coach or physical therapist.
Exercise technique does not need to be overemphasized, however. Studies are clear that posture and mechanics are poor predictors of pain or injury. Appropriate training programs and recovery strategies should be a primary focus, such as nutrition and sleep. For untrained people, especially kids, it is easy to overtrain.
Kids are resilient and heal quickly, but they are not invincible.
The benefits of childhood exercise
Research shows exercise carries many benefits for kids, including cardiovascular health, bone mineral density, lipid profiles, blood sugar control, muscle mass, and personal self-esteem.
Exercise comes in many forms, including organized sports, school P.E. class, playing with friends, and structured exercise programs. The best exercises are the ones someone enjoys doing. If you don’t enjoy something, you unlikely to stick with it.
One way to enhance the enjoyment of exercise is through participating in sports.
According to research, participating in sports is an outstanding way for children to develop physically, cognitively, and socially. No sport is best for development. I repeat no sport is best.
Furthermore, early specialization increases injury risk. For most sports, a sampling period is best. Children should be encouraged to sample many different sports to develop new motor patterns and enhance future learning.
After enjoyment, intensity and volume are the most important components of exercise. The exercise should challenge the body. If it isn’t hard or performed frequently, the results will be limited.
With that said, low-intensity exercise — such as walking— and low-volume exercise — once a week — can still provide benefits. As you exercise more and the body gets fitter, the challenge and frequency of exercise will have to increase.
All of this applies to adults and kids.
What about specific exercises? Again, myths often reign supreme. Many of the exercises touted as dangerous are safe and effective for growth and development. As a physical therapist, the following fundamental movements are staples in my practice for all ages.
The squat is the king of exercise
Squatting is a fundamental movement. It is how we sit down and stand up off of the floor. The squat is not only completed with a heavy barbell on the back. Squats can be effective without weight. There are variations with holding weights in one or both hands.
I teach all of my pediatric physical therapy patients how to squat. It is a great exercise for developing lower leg strength and improving coordination. It should be a staple in all P.E. classes, physical therapy clinics, and sports conditioning/training programs.
Deadlifts are safe and part of life
Another fundamental movement, the deadlift cannot be avoided. It is the act of picking something up off of the ground. As with the squat, you don’t need to develop all children into powerlifters. That does not mean they won’t benefit from learning how to effectively lift heavy things off of the ground.
The deadlift is safe and effective for lifting heavy objects. Even if a child has a rounded back, they are getting benefit and not at an increased risk for injury.
The deadlift and the squat are among the best exercises anyone can perform. I regularly use them with my pediatric patients.
Looking at the big picture
According to the CDC, almost 20% of all children in the US are obese. Granted, those statistics are from 2017–2018. There is a good chance the country has crossed the 20% marker. When breaking it down by age group, the prevalence was 13.4% among 2- to 5-year-olds, 20.3% among 6- to 11-year-olds, and 21.2% among 12- to 19-year-olds in 2018.
Taking it a step further, according to the American Diabetes Association, 210,000 Americans under age 20 are estimated to have a diagnosis of diabetes. While far lower than obesity, the rates are increasing every year.
Given these disturbing trends — some children are even developing atherosclerosis and other signs of heart disease — why would we message to avoid one of the best methods to improve health. Diet plays a larger role — processed food may be the most damaging thing to our health — but exercise is vital.
This does not mean children need to start body-building routines, but resistance training can be used for safe and effective exercise. Fundamental movements such as squatting, deadlifting, pressing, and rowing are great for developing strength, endurance, and power.
Physical activity isn’t restricted to activity in the gym. Going on hikes, playing in the yard, and riding bikes with friends all help the body. But if you want to introduce resistance training to a child, I encourage you to move forward. Injury risk still exists, just as it does with adults, but the benefits far outweigh them.
And the exercise will not stunt the child’s growth.