Physiology, Health & Exercise Lesson 17 z Osteoporosis- cause & effects zPrevention & role of...
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Transcript of Physiology, Health & Exercise Lesson 17 z Osteoporosis- cause & effects zPrevention & role of...
Physiology, Health & Exercise
Lesson 17 Osteoporosis- cause & effectsPrevention & role of exercise
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Osteoporosis
Includes: Osteoporosis & bone growth Effects of exercise on bone density
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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”
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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
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What is osteoporosis?
Other effects Loss of height Curvature of the spine Chronic back pain
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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
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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
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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
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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
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Risk factors for osteoporosis
Men Low levels of testosterone
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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!
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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
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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
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Exercise those bones!
Bones require regularweight-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
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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
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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?
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Treatment of osteoporosis
Prevention is better than cure: Regular weight bearing exercise Adequate dietary calcium & vitamin D
Both before late 20s
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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
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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