Kines100: Exercise, health, nutritionLast Lecture Outline Lecture 26 1. Nutrition and heart diseaseCurrent Lecture 1.Bone and the nutrients2. Bone Health Bone and the Nutrients • Bone is living tissue • Remodeling ◦ osteoblasts (build bone, create matrix/mineral)◦ Osteoclasts (dissolves bone, release minerals)◦ allows bone to reshape itself; adapt to stresses, heal injury, allows bone to be a Ca reservoir• Blood Ca is maintained +/- 3%• Decreased Ca intake will lead to low blood Ca• Vit D acts on mucosa cells triggering a greater rate of absorption• High Ca diet → absorb less than a fourth of Ca • Low Ca diet → absorbs half Ca◦ stimulates osteoclasts, dissolves bone, releases Ca into blood • Net Effect:◦ increased Blood ca▪ High absorption of Ca from gut▪ High resorption of Ca from bone ◦ High Ca diet → high blood Ca → stimulates osteoblasts (building bone); takes up Ca from blood • Blood Ca maintained at any cost to the bone ◦ high Ca diet → bone formation◦ low Ca diet → release Ca from bone • Negative Ca balance ◦ diuretics (excessive intake of protein, alcohol, caffeine) ◦ Fecal losses▪ excess phosphorus ◦ smoking • Osteoporosis ◦ Resorption is greater than formation; makes bones porous and weak ◦ Contributors ▪ menopause (estrogen protects bones)▪ Greater in women than in men▪ Low vitamin D (less efficient synthesis, lower sun exposure,▪ Low Ca intake◦ Prevention ▪ bone mass peaks at 35▪ Adequate diet ▪ Moderation in factors (diuretics)▪ Weight bearing exercise ▪ not smoking Bone Health • Does exercise delay the onset of osteoporosis?◦ Typical response to exercise: maintain/increase bone mineral density ◦ Weight bearing exercise most beneficial • Methods of Study◦ exercise or no exercise ◦ lack of stress on the body: bed rest/space travel'◦ results▪ 1% loss in bone mineral density per day in non weight bearing conditions ▪ consider a person that breaks a hip- takes away independence • Seen in competitive Female athletes ◦ high level of PA◦ Low levels of body fat ◦ undernourished ◦ consequence:▪ irregular menstrual cycles/amenorhea ▪ early age onset of osteoporosis (35)• Osteoarthritis ◦ classic age related disease ◦ prevalence of disease increase with each decade of life ◦ associated with wear and tear • Process of OA◦ repetitive impulse loading (wear and tear)◦ breakdown of bone (small microfraction)◦ remodeling phase (stiffening)◦ decreased shock absorption – leads to increased stress on articular cartilage ◦ eventual cartilage breakdown◦ Joint degradation • Candidates for OA◦ overweight individuals ◦ collision sports • Early competitive sport participation and OA◦ Does running promote OA?◦ Yes: bio mechanics are poor, over extended life of shoes, running on concrete surfaces, pre-existing injury◦ No: compares runners to swimmers, slightly less OA, increased blood flow to joints, cartilage normally has little perfusion, maintains integrity of synovial
View Full Document
Unlocking...