School-Based Resistance Training Strengthens Bones in Adolescent Girls

You’re never too old to exercise and start reaping the benefits of strength training. On the other side of the spectrum, you’re never too young, either.

A recent study examined the effects of regular weight training on bone formation in young girls. Sixty-two girls, divided into two groups, participated in their school gym classes as usual, but one group included 8 to 12 minutes of strength training as part of the class.

The study started when the girls were in 6th grade and lasted for two years. Dual-energy X-ray absorptiometry scans before and after the intervention revealed that 10 minutes a few times a week was enough to give the strength-training girls an advantage.

After two years, the girls who included strength training as part of gym class had 4.1% higher bone mineral content in the lumbar spine (L1-L4) area, and 5.6% higher bone mineral density.

The results also showed that intensity matters. The girls trained as vigorously or with as low an effort as they wanted, which was observed and documented. Girls who had trained with a higher intensity demonstrated advantages over low-effort participants. The numbers for bone mineral content and density for the girls who had participated with more enthusiasm than the others were 5.7% to 8.2% instead.

Just participating in strength training improved bone mineral density and bone mineral content significantly compared to regular gym glasses. However, more vigorous training offered even more benefits.

This study suggests that strength training could, and maybe should, be part of school gym classes. Our skeletons are most pliable at an early age, and there are no better ways to strengthen it than load-bearing activities like strength training.


A 2-yr, School-Based Resistance Exercise Pilot Program Increases Bone Accrual in Adolescent Girls. Translational Journal of the ACSM. 4(11):74–83, JUNE 1, 2019.

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Andreas Abelsson

Andreas is a certified nutrition coach and bodybuilding specialist with over three decades of training experience. He has followed and reported on the research fields of exercise, nutrition, and health for almost as long and is a specialist in metabolic health and nutrition coaching for athletes. Read more about Andreas and StrengthLog by clicking here.