Exercise’s Role in Building Bone

Parents always say, “drink your milk for healthy bones.”  They are correct due to the high amount of calcium and vitamin D supplied in milk–necessary for the lay down of new bone cells.  But exercise seals the deal.  Why?

Exercise’s Role in Building Bone

When the bone receives a load upon it via some form of physical work, such as weight training or any other exercise that puts a force on the skeleton, the “osteoblasts” (cells that help bone form) will be activated.  The osteoblasts bring calcium into the bone to help strengthen it up.

The Research: Why Start Young

A recent study published in Medicine & Science in Sports Exercise has recently suggested that the opportunity to build bone may happen as early as five years old!  The study found that children with the highest levels of moderate and vigorous physical activity at age five accumulated between 4-14% more bone mineral content at ages eight and 11 than those with the lowest levels of activity.  This suggests that exercise can help increase the propensity toward building bone–especially when starting at a young age.

Another study published in the Journal of Applied Physiology found that the lower a child’s calcium intake, the more important for daily exercise.  They researched girls and boys ages 8-11 who engaged in 25-40 minutes of physical activity per day AND consumed between 700-800 mg calcium per day.  They found that the group who consumed calcium with the daily physical activity built up and retained the greatest bone mass.

The Recommendations for Exercise for Children and Adults

The American College of Sports Medicine (ACSM) and American Heart Association (AHA) recommend that children partake in 60 minutes of some physical activity every day.  For adults, the ACSM and AHA recommends moderately intense cardio 30 minutes per day, five days per week.  If you cannot do that, they recommend vigorous intense cardio 20 minutes per days plus three days a week devoted toward strength training exercises (8-12 repetitions of each exercises two times per week). (1)

If you want to have the strongest bones, strength training should be added at least twice per week to make sure the skeleton receives the greatest exercising load. Here is a WHY TO exercise, in case you have forgotten!

The Recommendations for Calcium & Vitamin D

Peak skeletal growth happens between teenage years and the mid 20s.  Teenagers can accumulate up to 25% of adult bone during that time period. (2) Sadly, sodas (both regular and diet) tend to take the place of nutrient-rich beverages like milk.  As a result, calcium intakes have fallen short of the recommendations for children aged 4-8 to consume 1,000 mg per day.  See the Institute of Medicine (IOM) recommends below, which details the following most recently updated intakes of calcium and D for children and adults:


(1) ACSM and AHA Exercise Guidelines

(2) Bailey DA, Martin AD, McKay HA, Whiting S, Mirwald R. Calcium accretion in girls and boys during puberty: a longitudinal analysis. J Bone Miner Res. 2000;15(11):2245-2250.


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