By strengthening bones during their teenage years, people may be better prepared to ward off the harmful affects of osteoporosis later in life. It is well known that bone health is improved by doing weight-bearing exercises. The authors put these two ideas together to develop the first study of its kind, a test to see whether high-intensity jump training could strengthen the skeletons of teenage girls.
The authors assigned 56 ninth-grade girls to two groups, an exercise group and a control group. At the beginning, all participants filled out surveys about their diet and took tests of balance, strength, and power. Bone mineral density testing was done to check the amount and quality of the bones in various parts of their skeletons. These measurements were used to track how the specialized exercise program affected bone health.
For the first three months, the girls in the exercise group prepared their muscles by doing graded resistance exercises. They also advanced through a series of jump training, called plyometrics. This specialized training is an effective way to improve muscle strength and power, but it has not been tested to see whether it can strengthen bones. Participants received high school credit for exercising up to 45 minutes, three times each week. The control group did their routine activities but did not do any specialized exercises.
After nine months, participants repeated the tests of balance, strength, power, and bone density. For the most part, the bones of both groups showed improvement, which might have to do with normal growth patterns. However, compared to the control group, the exercisers showed a lot more bone strength in the upper part of the hip, had up to 29% better side-to-side balance, and had better leg strength.
Based on these measurable improvements and the consistent participation with the program, the authors conclude that “high school PE programs could include plyometric training and potentially reduce future risk of hip fracture.”