Most of us recognise osteoporosis as a disease of old age, and in most cases this is when the problems associated with osteoporosis are most evident.
Osteoporosis describes the loss of bone density and disruption of normal bone architecture with a greater risk of bone fracture. The degree of bone density loss is determined by many factors such as age, diet, gender, genetics, and medication. Many of these we are unable to change, but there is increasing evidence to suggest that the right sort of physical activity much earlier in life can have a significant impact on bone health which may translate to a positive benefit throughout a whole lifetime.
Bone is essentially a “plastic” material. This means that bone changes depending on the stresses to which it is subjected. Bone cells are continually being laid down- this is how a fracture repairs. Bone cells are also being resorbed by the body. Therefore if we subject our bones to increased loading, such as when we introduce a new sporting activity, our bones respond by becoming stronger. If we do this too quickly, our bodies are incapable of laying down new bone cells at the required rate and we put ourselves at risk of developing bone stress and ultimately a stress fracture. Astronauts suspended in a non-gravity atmosphere are at risk of losing bone density because their bones are no longer subjected to weight bearing loading and the body no longer receives the required signals to lay down more bone cells.
We know that we reach our peak bone mass-(when our bones are at their greatest density), in our 20s. That’s scary- after this stage we are in a state of gradual decline. So while we know that healthy diet and exercise are important throughout life, they are vitally important during childhood and adolescence. What the research is now showing us is that the period at which we are most able to modify the mass and strength of our bones is even more defined than we earlier thought. It seems that the best time to influence our skeletal strength is in early puberty. The really exciting thing that the research is showing us is that the exercise doesn’t need to be time-consuming or elaborate. A well-known study called “Bounce at the Bell” was carried out in Canada in 2005. This study examined the effects of simple jumping exercise on bone density in children aged from 9-11. The children performed a set of 10 jumps in which they jumped and landed on two feet, three times a day, at bell time, over a period of one school year. The study showed that there was a greater increase in bone strength and bone mass in the group that did the exercise compared to the group which did not. Simple but effective.
Sadly, we live in a world in which simple forms of physical activity happen less incidentally as a form of regular daily activity. Technology claims more of our children’s’ time, and nutrient poor foods comprise a larger part of their diets. The take home message from this column is that weight bearing, high impact activity in childhood and adolescence is a way in which we may be able to influence our bone health into the very late stages of our lives. And given the changing world in which we live, and the ever increasing demands on our health dollar, this is a very important message indeed.
Michelle Sintmaartensdyk Is a Partner at the Oamaru Physiotherapy Clinic . She has postgraduate qualifications in Manipulative Physiotherapy , Sports Medicine and is a Registered physiotherapy Acupuncturist.