Exercise in youth makes for stronger, bigger bones through life

Our bone is living tissue that responds to the forces that act on it - it gets stronger when we exercise. Now a new study suggests exercising when young helps bones grow big and strong for life, and that this effect persists during aging.

To arrive at this finding, researchers compared the differences between the throwing and non-throwing arms of major league baseball players measured at different points in their careers to differences measured in non-baseball players.

They found that half of the bone size and one-third of the bone strength benefit of exercise performed during youth persisted throughout life.

Lead author Stuart Warden, an associate professor at Indiana University-Purdue University Indianapolis, says:

"This is an impressive level of maintenance, particularly considering that the baseball players had not thrown, or in other words, exercised, in over 50 years and were aged in their mid-80s."

The researchers were not, however, surprised to find that the amount or mass of new bone added as a result of exercising during youth was gradually lost as the players aged.

Prof. Warden says it is "not energy efficient for the skeleton to maintain its mass in excess of its needs."

As we age we lose bone from the inside

But Prof. Warden and his colleagues were still intrigued by the question - how can exercise during youth have a lifelong benefit on bone strength but not bone mass?

You can strengthen any load-bearing structure by adding more mass, especially where it is needed most. And bone is no different, as Prof. Warden explains:

"Exercise during youth adds extra layers to the outer surface of a bone to essentially make the bone bigger. This gives you more 'bang for the buck,' as the addition of a small amount of new material to the outside of a bone results in a disproportionate increase in bone strength relative to the gain in mass."

But as we age, we lose bone mostly from the inside, not the outside. Prof. Warden says this means the bigger and stronger bone that amasses as a result of exercising in younger years endures for a lifetime.

Exercising later in life also benefits bone health