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Exercise and Bone Health

Exercise and Bone Health. Wolff's Law - Bone remodels according to functional demands Exercise increases mechanical stress and strain results in an increase in growth hormone levels which contributes to increasing bone mass and density

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Exercise and Bone Health

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  1. Exercise and Bone Health • Wolff's Law - Bone remodels according to functional demands • Exercise increases mechanical stress and strain • results in an increase in growth hormone levels which contributes to increasing bone mass and density • makes bones stronger, stiffer, and able to store more energy • Overtraining, especially in children and older adults may be counterproductive.

  2. Research Factors: These factors should be controlled when examining the effects of exercise on bone health. • Age • Exercise protocol • type • intensity-weight bearing • duration • specificity • Length of the study (Studies must often be performed for an extended period of time in order to see a measurable effect.)

  3. Research Factors (continued): • Compliance with established research protocols (this is important in order to be able to compare one study with another.) • Gender (There have been different effects observed between males and females.) • Hormone levels • estrogen • testosterone • cortisol • growth hormone • How is bone size, quality measured? • Are the bone sites measured appropriately?

  4. Research Study 1 • Nilsson and Westlin, 1971. They found that bone density of the femur increases as the fitness level (participation in exercise) of individuals increased. All exercising groups (whether competitive athletes or not) had higher bone densities than sedentary controls.

  5. Research Study 2 • Jones et al., 1977 They found in tennis players that the thickness of bones in the dominant arm is greater than in the non-dominant arm. Sedentary individuals have no difference in bone thickness or strength between the dominant and non-dominant arm.

  6. RESULTS OF EXERCISE TRAINING 1. Exercise training can increase bone density and mass (and energy absorption) in youths and adults (young and middle-age) 2. In the elderly, exercise can maintain bone mass or slow loss of bone mass

  7. RESULTS OF EXERCISE TRAINING (continued) 3. Types of exercise that are most effective: • weight bearing (Walking/running, stair climbing, etc.) • weight training 4. Exercise increases material properties through mechanical stress and strain * Chronic exercise can maximize bone mineral content, volume

  8. Piezoelectric Effect • A flow of electrical current that results from compression of certain materials. • In bones, a site of compression produces a negative electrical potential with a positive potential elsewhere in the bone. • This minute flow of current in bone causes osteoblastic activity at the negative site. • The result is increased bone deposition at the compression site.

  9. Benefits of exercise are optimized or enhanced by: • adequate caloric intake • adequate Ca2+ in diet • adequate Vitamin D intake • adequate levels of hormones • estrogen • testosterone • growth hormone

  10. OSTEOPOROSIS: HEALTH IMPLICATIONS Osteoporosis - critical reduction in bone mass to the point that fracture vulnerability increases • Affects 6.3 million Americans • Estimated cost of 7-10 billion dollars annually

  11. Exercise and Osteoporosis in Female Athletes Several years ago a problem with vertebral degeneration was noted in a population of certain female athletes. Investigation showed that many of these young women had bone mineral content similar to elderly women and were suffering from osteoporosis

  12. Exercise and Osteoporosis in Female Athletes (continued) Female Athlete Triad A. Poor overall nutrition - especially caloric restriction; decrease in dietary Ca2+ B. Overtraining C. Low percentage body fat. The "set point” below which the normal menstrual cycle is disrupted

  13. Exercise and Osteoporosis in Female Athletes (continued) Female Athlete Triad (continued) • occurs in small but significant % of population of athletes, active instructors • most common in runners, gymnasts, aerobics instructors • associated with disturbances in menstrual cycle

  14. Exercise and Osteoporosis in Female Athletes (continued) • varies from individual to individual based on nutritional status, overtraining, etc. • With amenorrhea (cessation) or oligomenorrhea (missed periods) estrogen levels drop dramatically. • young women may lose bone mass (osteopenia)

  15. Exercise and Osteoporosis in Female Athletes (continued) • If nutrition, overtraining, and low % body fat issues are dealt with then normal menstrual cycle will usually resume • Some recovery of bone mass noted (long-term effect unknown)

  16. Exercise and Osteoporosis in Female Athletes (continued) • Education of coaches, athletes to this problem while the athletes are teens is absolutely critical. • Luteinizing hormone (LH; pituitary hormone necessary for ovulation) can decrease up to 6 months before we see drop in estrogen and disturbances in the menstrual cycle. Can this be used as a screening/prevention tool?

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