Generally, bone density develops rapidly during puberty, peaks between the ages of 20 and 30, and is gradually and progressively lost in maturer years. Women going through menopause normally have an accelerated loss of bone mass for several years as they lose the protective effect of oestrogen.
The good news is that bone is a living tissue and it can be remodelled by the body. In response to mechanical stress, bone density increases and the bone strengthens. In the absence of mechanical stress, bone loses density and becomes weaker.
So building bone strength in adolescence and early adulthood, and minimising bone density loss in later years, are the best strategies for preventing osteoporosis. And this is where exercise comes in.
The role of exercise
The best ways to help counter osteoporosis are to build optimal bone density early, as a measure to offset the inevitable losses that occur with ageing, and to work at maintaining bone density in later years. For this, exercise and adequate intake of calcium and vitamin D are essential.
While the process is affected by genetic and lifestyle factors, generally about 90% of bone mineral content is deposited by the end of adolescence. Young bone is more responsive to exercise stress than older bone and the period between ages 9 and 20 is especially important for building optimal bone density. So exercise during adolescence is an important factor for building peak bone mass.
For adulthood and into mature years, activities such as running, ball sports and walking, in which the weight of the body is borne by the feet and legs are more effective for maintaining bone density than non-weight-bearing activities such as cycling and swimming.
Studies also show that among older women, a lifetime of regular physical activity encourages greater bone mineral mass.
There are two kinds of exercise recommended for healthy bones:
Weight-bearing: Activity that is done on your feet such as walking, jogging, tennis, dancing or golf. Resistance exercise: Activity that involves lifting weights that involve the whole body, particularly focusing on the hips, spine, arms and legs. This can include free weights or weight machines and also swimming, as any movement done in the water makes your muscles work harder.
Health experts recommend 30 minutes of moderate-intensity exercise on most days to keep you fit and healthy and to help your bone health. The best exercise for you will depend on finding the safest, most enjoyable activities, given your overall health and bone density.
It is important however, that you get the all clear from your doctor before starting an exercise program, particularly if you have lived a sedentary life or you have been diagnosed with osteoporosis.