CHICAGO -- If you're going to fall and break something, you should at least have a good story to tell.
I have broken nine bones. No, I was not abused. Some stories are better than others. The last bone I broke, the ulna in my left arm, involved a ski jump. Good story, except for the part about me being left-handed.
The goal for most people is to keep bones intact. For aging populations, exercise is a critical component of strengthening bones to preventing fractures.
If you move a lot, lift heavy things, walk, jog, cycle, jump, dance, Pilate, hike or ski, then your muscles and connective tissues will be stronger and more functional. You'll be more flexible, coordinated and agile.
Aye, but here's the rub: Exercise puts you at greater risk. Sure, you're stronger and more coordinated, but the person going out for daily jogs is more likely to go flying after slipping on something than the person who sits all day. Your ability to stay upright increases, but the risk that you could fall increase too. It's a Catch-22.
Just do whatever you want.
Psych! I'm not letting you off that easy, because exercise increases bone density and, more importantly, bone strength.
Many studies show the effect of exercise on bone adaptations. The 2008 textbook "Essentials of Strength Training and Conditioning" shows a picture of how additional downward gravitational force affects the skeleton.
Consider your femur (thighbone). Imagine you put a bunch of extra weight on your back and move around, and up and down. That extra downward force causes the bone to bend from the weight. When that happens, previously dormant things called osteoblasts migrate toward the bone when it bends, and they lay down collagen fibers. These collagen fibers mineralize, and that yields new bone growth. Fantastic!
That's the theory, but there isn't a lot of consensus in the research about what this means for the average person. I did some digging, and discovered that when it comes to the effect of exercise on the bone health of aging populations, Wendy Kohrt is the expert.
I started off by asking her if resistance training actually increases bone density.
"It can happen," said Kohrt, who is a professor of geriatric medicine at the University of Colorado. She explained that we can't say with absolute certainty it happens in humans, but the indications are that it does.