Effects of Exercise on Bones
Many studies have shown exercise has a direct effect on bone development and maintenance.
The short term effect of exercise on the skeletal system is smoother movement, as synovial fluid (fluid that surrounds most of the joints) is secreted into the joints when they are warm and fully mobilised.
The ‘warm-up’ is essential in the initial stages of a workout session in order to prepare the joints for greater more stressful activity.
Long term, the condition of bone may be improved by exercise as it responds to mechanical stresses. These mechanical stresses usually take the form of skeletal muscle pulling at their points of attachment (their origin – where the muscle starts, and their insertion – where the muscle ends). Where these mechanical stresses are applied most frequently it has been shown that more mineral salts are deposited and more collagenous fibres are produced.
Therefore both the density and size of bone in thee areas may be increased and these changes in bone structure are stimulated by increased loads being placed on the skeleton. This has been borne out by greater bone mass being observed in weight lifters than in other lighter endurance athletes such as joggers.
Other examples include racquet players who have been shown to have greater bone density in their playing arms. It has even been shown that if a leg is immobilised by being in plaster, due to a fracture, that even after a few weeks bone becomes de-calcified from lack of mechanical stresses.
Whilst it may therefore be considered beneficial to utilise exercise to maintain healthy bones, great care must be taken with children whose bone and muscles are still developing. They should not be subjected to forms of sport involving high degrees of mechanical stress, partly because of the weaknesses which still exist within the bones, and also because of adverse effects on the development of these bones before maturity.
Osteoporosis is a bone disease in which the amount of bone is decreased and the natural bone is impaired. Bone becomes more porous and thinner. This makes the bone weaker and more likely to fracture.
Studies continue to show a benefit from exercise.
The ‘use it or lose it’ principal, again, continues to be proven to play a major part in bone preparation, continued strength and flexibility throughout life.
(c) Paul Graham