KINES 101 Lecture Notes - Lecture 2: Stress Fracture, Osteoclast, Reference Group
Document Summary
% difference between different athletic groups and non-athletic reference group regarding bone parameters measured at the hip. An astronaut who spends a long time in space will often return to earth with weaker bones, since gravity has not been exerting a load on their bones (decreased muscle activity in zero space). Bone undergoes remodeling in response to mechanical stresses placed upon it, leading to changes in the external form and internal architecture of the bone. If loading increases, bone will remodel at the site of stress to become stronger to withstand that load. If loading decreases, bone will remodel at the site of stress and become weaker since it does not have the same load. Long bones are thickest midway along the shaft that is where bending is greatest. Curved bones are thickest where they are most likely to buckle. Periosteal and/or endosteal expansion (during growth only) occurs. Mechanostat theory responsiveness to typical strains within a physiologically safe range.