Children’s strength training

Children’s strength training has, for too long, remained as a controversy. There are such beliefs that children in prepubescent age can’t achieve strength from resistive strength training, and that it can cause injuries especially on the growth plates in the bone structures of children.

In this text, I have reviewed some scientific publications that I have found in internet, and that are freely available.

In the first study, 18 boys and girls were divided in two groups; Group 1 consisting of eight boys and two girls and group 2 (control group) of seven boys and a one girl. All volunteers were examined physically and rated following a Tanner Scale of pubescence.  Physical examination as well as weight, flexibility and skeletal maturation of the volunteers were rated.

The training sessions lasted for 25-30 min each, three times a week for nine weeks. The sessions consisted of flexibility training, warm up and the strength exercises generally in three sets of ten. The strength training was progressive and the resistance of the training increased during the study period. The training sessions were supervised.

The mean strength gain from all the measured exercises was 42,9 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} in Group 1, and 9,5 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} in  Group 2. Group 1 gained 4,45 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} increase in flexibility, while the control group gained 3,57 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637}. While the increase of the flexibility in group B isn’t statistically important, it shows, that the strength training does not decrease the flexibility. No injuries were detected during the study period. (1)


In the second study reviewed here, 11 boys and 4 girls of ages 7 to 12 years were placed on an 8 week strength training program, and then for 8 week period of detraining. Control group consisted of three boys and six girls.  Strength training was carried out two times a week, on equipment designed for children. Tests were: 6 RM (repetition maximum) in leg extension, 6 RM chest press, vertical jump, as well as flexibility.

Findings were 53, 5 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} increase in leg extension and  41,1 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} increase in chest press while control group gained less than 8 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} in average. In detraining period there was approximately 20 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} decrease in upper body strength and 30 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} decrease in lower body strength.(2)

In the third study reviewed here, 14 boys and girls were placed on eight-week strength training period. Control group in this study was a randomly selected group of 9 children in mean age of 9.9 years. Trainings were carried out twice a week. Five different exercises were done by each child, in sets of 10-15, with 50-100 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} resistance of a given 10 RM. In this study, the study group gained in strength 74,3 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} as compared to the control group with 13,5 {49f584108a086bd6c91a2d6dac29820e7f4d6684659c76d93d60f9b2f4fa9637} gain in strength.(3)


All the studies above are consisting of studies based on strength training program. Now, difference between strength training and for example weightlifting and powerlifting should be made (and then there is of course CrossFit). Both weightlifting and powerlifting are competitive sports and in both of them the athlete’s ability to do single maximum lift is measured. In weightlifting, there are two competitive lifts: the snatch and the clean & jerk and in powerlifting are the squat, bench press, and dead lift.

For a long period of time, these sports were considered to be highly dangerous for children. In retrospective study it has been found that both weightlifting and powerlifting are safer than lots of other sports. The explanation could be that to perform the complex multi joint lifts in weight lifting, the child has to gradually progress the training loads to learn the technique. In the beginning a child or adolescent has to master the exercises using submaximal loads. There are several studies showing same kinds of results. In addition, today, the methods to record the injuries are very accurate, in comparison to those times when the idea of risks in these sports was created. (4)

As a conclusion, based on these four articles, strength training in children can improve muscle strength while being safe. In addition, it does not decrease flexibility in children, and it can, in fact increase it. Well designed and supervised strength program is a way to increase the wellbeing and health of a child. The benefits related to the strength training are likely to outweigh the possible risks. It is important to stress the technique, instead of the weight lifted. (4)

On the video below there’s Henri’s (14 y) clean & jerk 27,5 kg, which isn’t nearly his maximum result (39 kg). Henri is a CrossFit Kid, and a competitive alpine skiier for many years. Henri has also competed in weightlifting.


Author: Sanni Pisto is a CrossFit L1- and CrossFit Kids trainer  and a student of sports medicine.

1 Sewall L. , Micheli L.. (1986). Strength training for Children. J pediatr Orthoped. 6 (2), 143-146.

2 Faigenbaum A., Westcott W., Micheli L. . (1996). The Effects of Strength Training and Detraining on Children. Journal of Strength & Conditioning Research. 10 (2), 67-136.

3 Faigenbaum, Avery D.; Zaichkowsky, Leonard D.; Westcott, Wayne L.; Micheli, Lyle J.; Fehlandt, Allen F.. (1993). The Effects of Strength Training and Detraining on Children. Pediatric Exercise Science. 5 (4), 339-346.

4 Holly J. Benjamin, MD; Kimberly M. Glow, MD, MPH . (2003). The Effects of Strength Strength Training for Children and Adolescents . The Physician and Sports Medicine. 31 (9)