98 Chapter 5: Training for Strength Figure 5.5 depicts bone density scans, as taken by dual-energy x-ray absorptiometry (DEXA), of two active duty servicemembers. The graph on the left depicts a 40-year old female who regularly performed endurance training (e.g., running, rowing), but rarely performed strength training. The graph on the right depicts a 43-year old male who has performed strength training for over 20 years. As depicted in the below graphs, the female servicemember is currently at the 10th percentile for bone density for her age. Conversely, the male servicemember is well above the 90th percentile for bone density for his age. Higher percentiles represent higher levels of bone density and a reduced risk of osteoporosis and fracture. Figure 5.5. Impact of Strength Training on Bone Density Figure 5.6 depicts the changes in bone density for the female servicemember after one year of strength training. Although her bone density did improve, it was not statistically significant. The takeaway message is that strength training can help to improve bone density regardless of age, but the earlier you start strength training the better. Strength training not only reduces the risk of osteoporosis, but it also reduces the risk of fracture as well. Research shows that risk for fracture increases significantly when bone density is less than 1 g/cm2 (Doroudinia & Colletti, 2015). Figure 5.6. Changes in Bone Density with Regular Strength Training
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