Physiology, Health & Exercise

1. Physiology, Health & Exercise Lesson 17 Osteoporosis- cause & effects Prevention & role of exercise

2. Osteoporosis Includes: • Osteoporosis & bone growth • Effects of exercise on bone density

3. What is osteoporosis? • Long term condition. • Bones become progressively more porous & brittle • Literally means “porous bones” • Increased risk of fractures • Sometimes called the “silent thief”

4. What is osteoporosis? • Even minor falls e.g. stepping off a kerb, can cause fractures • Most common sites of fractures: • Wrist • Spine • Hip • Bones tend to break into fragments (rather than a clean break) • Impossible to reassemble, so can require surgical treatment

5. What is osteoporosis? Other effects • Loss of height • Curvature of the spine • Chronic back pain

6. Bone density • Bones is living • Constantly renewed throughout life • Bones grow in size during adolescence & childhood • Can completely renew skeleton in 2 years at this stage (takes 7-10 years for adults) • From late adolescence bones stop growing in length & instead become stronger- more dense

7. Bone density • if adequate calcium intake in diet & are physically active then: • Peak bone density- in late 20s to early 30s • At age 35 balance between bone breakdown & new formation  stable bone density • After 35 bone loss increases part of natural aging process • Rate of approx 1% per year for females • After menopause rate loss 2-3% a year

9. Who gets osteoporosis? • Men • Women • Children • Most common in menopausal women • 20-50% of women over 50 are affected • 75% of women over 90 are affected • 1 in 12 men in UK affected • Men at lower risk because tend to have larger and stronger bones

10. Risk factors for osteoporosis Women • Lack of oestrogen caused by • Early menopause (before age of 45) • Missing periods for > 6 months (excluding pregnancy) as a result of over exercising or over-dieting

11. Risk factors for osteoporosis Men • Low levels of testosterone

12. Risk factors for osteoporosis Both men & women • Diet lacking calcium & Vitamin D • Vitamin D required for absorption of calcium by digestive system • Family history • Smoking & excessive alcohol consumption- both increase rate of bone loss • Low body weight • Long term immobility • Getting old!

13. What causes osteoporosis? • 99% of body’s calcium is found in skeleton • When diet low in calcium, body draws on reserves in bones to make up deficit • So advantage to “bank” more calcium in bones before reach peak bone density- in late 20s to early 30s

14. What causes osteoporosis? • Oestrogen maintains bone tissue by stimulating the formation of new bone • Oestrogen • enhances intestinal calcium absorption • Limits calcium withdrawal from bone • Low oestrogen levels • Reduce the activity of bone cells • Increase risk of calcium loss from bones

16. Exercise those bones! • Bones require regular weight-bearing exercise • E.g. walking, dancing, jogging, tennis • Why not swimming or cycling? • Exercise: • Puts force through the bone to stimulate growth • Strengthens bones • Strengthens tendons, ligaments & point of attachment at joints

17. Exercise those bones! • Resistance exercise also strengthens bones • E.g. weight training • Bed-ridden individuals have increased bone loss as do astronauts in zero gravity

18. Treatment of osteoporosis • No cure! • Can halt or reverse progress of disease with: • Exercise • Oestrogen in form of HRT (hormone replacement therapy) or calcium supplements • Caution choose exercise carefully if have osteoporosis – need moderate intensity- why?

19. Treatment of osteoporosis • Prevention is better than cure: • Regular weight bearing exercise • Adequate dietary calcium & vitamin D • Both before late 20s

22. Female athletes & osteoporosis • Extreme levels of exercise by young athletes can cause osteoporosis Reason • Very intensive training • Restricted diet • Combined reduce body fat • Can cause periods to stop & drop in oestrogen levels

23. Female athletes & osteoporosis • Worrying as at a time of max potential bone growth • Some young athletes have bone density of women in their 70s • These bone losses are irreversible • Female athlete’s triad • Intensive training & • Restricted diet & • Low body fat