When it comes to kids and strength training, parents often want to know at what age their children should start lifting weights.

Urban legends of stunted growth, fractured growth plates and prematurely inflated physiques have made many parents understandably hesitant when it comes to involving prepubescent kids in resistance-training programs.

Tall tales and fear-mongering aside, the best answer to the “How old?” question may surprise you.

While there is currently no scientific evidence to suggest that there is a perfect chronological age to start weight training, “freshman year” (of high school) seems to be the widely accepted safe zone to begin training. This is not unfounded, as it represents a developmental milestone right in the middle of puberty. During this time, muscle, strength and performance gains from resistance training can be optimized.

Peer-reviewed research, however, has yet to report any negative health consequences from resistance training in children as young as 5 years, assuming proper movement and progression is introduced under experienced supervision. It appears an overwhelming majority of youth resistance-training injuries are primarily due to equipment accidents (e.g., weight falling on them and tripping in the weight room) or overzealous coaching that ignores proper program introduction and progression. Furthermore, concerns about abnormal body morphology (getting too big) prior to puberty are unfounded due to the minimal amount of natural anabolic hormone available in a child’s body.

In actuality, it appears that prepubescent children involved in a supervised, progressive resistance-training program experience improved fitness, favorable effects on bone density, improved movement ability and a reduced incidence of athletic injuries.

Before visions of 5-year-olds hoisting heavy barbells above their heads keep you up at night, it’s important to understand that weight training is another word for resistance training. Resistance to movement can come in many forms. Gravity, heavy backpacks, stretch bands, dumbbells and other implements can add resistance to a movement, making it more challenging. When an increased amount of muscular force is required to move (due to resistance), the body gets stronger. When this happens regularly and strategically it’s resistance training.

While most parents would be O.K. with their children carrying a 5-pound backpack as they run off to school, the idea of their children holding a 5-pound dumbbell while performing a squat may set off the “danger” alarm. In both scenarios, the external weight merely represents an increased amount of resistance to movement. Either type of resistance can function to make the muscles associated with a movement stronger.

To reap the benefits and minimize any risk with a resistance training program for kids, consider the following four questions to determine if a child is ready to benefit from resistance training:

1. Can the child perform movements such as squats, lunges, push-ups and pull-ups (horizontal and/or vertical) correctly with his or her own body weight? If not, adding additional load (e.g., speed, resistance) to a dysfunctional movement pattern makes little sense. If the child can perform these movements easily and repeatedly, adding small amounts of resistance keeps the body adapting and getting stronger.

It’s important to consider, however, that many children struggle with strength-to-weight ratio during body-weight exercises. Take the push-up, for example. A child with an elevated body weight in comparison to his or her level of strength may not be able to perform this exercise. Instead, doing a bench press movement with dumbbells allows for strength gains without using body weight. Some weight-training equipment functions to create sub-bodyweight resistance. For children who struggle with bodyweight exercises, these may be a better first choice.

2. Does the child have the intrinsic focus, attention span and desire to learn the proper way to resistance train? Supportive parents and great coaching combined with an uninterested/unfocused child are still a poor match. Safety during resistance training depends on a child’s ability to understand and respond to coaching.

3. Is the environment the child will be training in safe, supportive and positive? It’s important that a training environment for kids caters to a wide range of skills, sizes and general level of awareness. A crowded gym with people, weights, medicine balls or other implements in motion can prove extremely dangerous for young children. Additionally, adult-sized equipment may not be appropriate for small bodies. If the culture of a gym or training area is intimidating or otherwise negative to a child, it could turn him or her away from exercise for a long time.

4. Is the person in charge of the child’s program experienced and knowledgeable about the intricacies of youth physical and cognitive development?

If the answer is “no” to any of these questions, your child will receive little benefit from an organized weight-training program. Rather, his or her risk of injury will be significantly elevated.

In this case, focus on keeping your child active with things he or she enjoys. Kids don’t have to “train” to be fit and healthy. However, if and when they express an interest in lifting weights, a proper resistance-training program is a safe and effective way to improve fitness and performance.

It's never too late to learn and to expand your client offerings! Check out other ACE Certifications or ACE Specialist programs, such as the Youth Fitness Specialist program.