- Dietary
- Hormones
- Exercise
Factors That Influence Bone
________ will change in response to the _________ it encounters
Bone; Stresses
- Muscle pulling on bone → joint reaction forces
- Impact → ground reaction forces
Effect Of Exercise On Bone
________ _____ is more metabolically active – can respond to changes in
mechanical loading more readily
Spongy bone
- Hip
- Wrist
- Spine
The most likely sites of fracture are areas with high spongy bone content
Goal: reach the fracture threshold later in life
Goal of Role of Exercise
increase peak bone mass
Exercise early in life
prevent bone loss
Exercise later in life
- fall prevention
- Improved strength
- Improved balance and coordination
Other benefits of exercise
Effect of exercise on bone:
Bone _______ > Bone resorption
formation
Force applied to bone is sensed by the osteocytes
→
proliferation of
osteoblasts
→
bone formation greater than bone resorption in response
to exercise
Effect of exercise on bone:
▪ Porous bones (reduced bone mass) → increased risk of fractures
▪ The proportion of collagen and minerals is normal but there
is a decrease in mass
Osteoporosis
Any factor that stimulates bone resorption or inhibits bone formation (or both)
Osteoclast activity > osteoblast activity
(bone resorption) (bone formation)
Cause of reduced bone mass
▪ Calcium/Vitamin D deficiency
▪ Older age (likelihood increases with age)
▪ Body build/weight (small body frames have higher risk)
▪ Gender (80% of cases are female)
▪ Lack of exercise
▪ Family history (higher chance if your sibling or parents have osteoporosis)
▪ Menopause (one of the strongest risk factors)
▪ Amenorrhea (lack of menstruation from low body fat increases a woman’s risk)
▪ Race (those of European or Asian descent have the greatest risk)
▪ Drugs (cortisone)
▪ Alcohol (2+ drinks a day increases risk),
▪ Smoking
▪ Eating disorders (higher risk in both men and women)
Risk factors for osteoporosis
Decreased bone mass and density that causes thinning of
bones and increased risk of fracture; normal ratio of bone mineral to matrix;
usually not associated with pain unless fracture occurs; diagnosed with bone
scan and usually not detectable with blood tests
Osteoporosis
Decreased mineralization of newly formed bone matrix at sites
of bone remodeling as a consequence of Ca2+ deficiency (due to Vit.D
deficiency); associated with achy bone pain
Osteomalacia
Congenital disorder that affects production of type I
collagen due to genetic mutation; brittle bones that fracture easily, often in
childhood or adolescence; pain associated with fractures
Osteogenesis imperfecta
