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Jumping to Conclusions about Bone Strength

Most of our bone mass is built during the first 20 years of our lives. Weight-bearing activities like walking, running, lifting weights,and jumping rope help build the strongest bones. But medical science has a long way to go before it can figure out which activities are best at building bone.

The authors measured the results of jumping rope on the bone strength of high school girls. The study included 37 girls who were past puberty. They were divided into three groups. The "high volume" group did 10 minutes of jump roping, five days a week. The "low volume" group did five minutes of jump roping. The control group did 10 minutes of walking and stretching. All the girls had measures of bone strength done before starting the program and after four months.

Two separate tests were used for measuring bone density. One was
a simple ultrasound of the heel. The second, called dual energy X-ray absorptiometry involves a broader scan of the skeleton. It is considered the best test, but it is expensive and difficult.

After four months, bone density increased 6.1 percent in the high volume group, 4.1 percent in the low volume group, and 1.1 percent in the control group. These numbers suggest that jumping rope is an effective way to build bone for girls.

The researchers were also interested in how the two measures of bone strength compared. This study showed that both measures showed similar improvements in bone strength, especially in the lower body.

This data supports the idea that heel ultrasound can be an effective way to measure bone strength. However, the authors caution that the data might be different with older women or with other forms of exercise.

References: Mark G. Arnett and Bob Lutz. Effects of Rope-Jump Training on the Os Calcis Stiffness Index of Postpubescent Girls. In Medicine & Science in Sports & Exercise. December 2002. Vol. 34. No. 12. Pp. 1913-1919.

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