Stay tuned into this live blog to keep up with one of the yearly major events organized by the Kinesiology Department!
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11:17 - Although 150 minutes/week is the recommended amount of physical activity per week, Dr. Kohrt says her research team's findings were that it takes more than that - closer to four hours - to improve skeletal health enough to reduce the chance of hip fractures.
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11:18 Nurses' Health Study - Women who were doing more physical study had a lower risk of hip fracture. Women who walked more briskly than average or slow-paced walkers had a lower risk yet.
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11:19 Dr. Kohrt presents a study that shows sitting more than 50 hours a week brought on a higher risk of hip fracture.
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11:20 Dr. Kohrt's presents her committee's findings that exercise can increase bone mineral density (BMD) of the spine and femur. Says that after examining 15 meta-analyses of bone density tests, all but four found exercise had significant effects of exercise on BMD.
Exercise intervention studies reveal that the spine, which has a high turnover rate, shows that it is an area of the skeleton upon which exercise has a very beneficial effect.
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11:24 Weight bearing, endurance training confers benefits for the spine and the hip. Resistance training showed benefits of the neck or hip regions, Kohrt says. Shows one of her own studies, comparing high- and low-impact exercisers, comparing change in BMD. Neck region: not benefited in the low-impact group. She says when you think about most resistence training, it's in a sitting position. "Now you're not getting the benefit of how the femur is interacting with the pelvis," she says. Lumbar/Spine comparison has comparable results for the two groups.
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11:29 Part Two of the talk: Kohrt's thoughts on the mechanisms of exercise affecting bone health. She says one of the best indicators of the positive correlation is considering the effect of inactivity. Presents a study that shows the effect of bed rest on bone health, after 17 weeks decreased bone health of the total body by 1.4%. And they showed no recovery six months later.
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11:36 What type of exercise program is most likely to increase bone mass: high magnitude of straining, few repetitions; dynamic, not static; high strain rate; diverse and unique strain distribution; specific rather than general. "If you want to increase bone density in the hip, you have to focus on exercise that will target the hip."
---11:39 Why get people to exercise instead of taking a pill to improve bone health? She offers two reason:
1. When you give a drug, it's going to act on all regions of you skeleton... In contrast when you use exercise, you are specifically influencing the regions of the skeleton that are chemically and structurally related to the physical activity you are doing..." It's more mechanically appropriate than pharmaceuticals. Exercises must be designed to target the weak regions of the skeleton.
2. Exercise targets the attack against osteoporosis.
Fun Fact: If you run, you may get all the skeletal benefits within the first five minutes of your run, she suggestions. (It only takes a few loading cycles to stimulate results of bone health.)
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11:48 Even more fun fact: Why are cyclists' bone density lower than the average person's? They are losing bone over one year of training and competition, the same loss seen in post-menopausal women. Why? Her research team is looking at the possibilities, like the loss of calcium through sweat. "We think the timing of when you take calcium relative to when you exercise could be very important," not just for cyclists, but anyone losing a lot of sweat.
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11:58 Her suggestions for maximizing positive effects of exercise on bone health:
1. Avoid physical inactivity.
2. High-intensity exercise is probably more effective than moderate-intensity exercise.
3. Strive for multiple exercise sessions per day.
4. Take calcium before working out.
Thank you, Dr. Kohrt for visiting our the SPH! We are honored to have had the opportunity to learn from your expertise.
The article mentions different exercises targeting different areas as far as bone density. A very effective form of weight-bearing exercise that works all the bones at once, in fact every other part of the body as well, is rebounding on a mini-trampoline. I think it should be promoted more because of its many advantages and ease of use. It would be interesting to see some studies on how many minutes per week or rebounding is needed to produce a measurable difference in bone density.
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