Although cases of osteoporosis have increased, weight-bearing exercise can help, writes Giles Warrington
THERE HAS been a dramatic increase in the incidence of osteoporosis (thinning bone disease) and the related high occurrence of fractures in recent years. It is estimated that the proportion of the Irish population over 65 years of age will rise significantly and, as a consequence, the incidence of osteoporosis will dramatically increase in the future.
The US National Institutes of Health has defined osteoporosis as "a skeletal disorder characterised by compromised bone strength predisposing a person to an increased risk of fracture".
Osteoporosis and related elevated risk of fractures has emerged as a major public health concern, and its prevalence is increasing.
Current data from the UK, which would closely mirror Ireland, suggests that osteoporosis may affect one in three females, and more than one in 12 males and is responsible for 200,000 fractures per year, and 40 deaths per day in the UK.
Based on current evidence, it has been estimated that a 50-year-old Caucasian woman has a 40 per cent risk of a fracture during her remaining lifetime.
Although osteoporosis is typically associated with post-menopausal females and the elderly, more recent evidence would suggest that it has its early origins in childhood and during critical phases of growth and development. Determinants such as poor nutrition and lack of appropriate weight-bearing physical activity during these early years could be contributing factors for bone health in later life.
Bone usually reaches its peak density in the late 20s. After this point, and as part of the natural ageing process, your bones become less dense and, as a consequence, are weaker.
Osteoporosis is often referred to as the "silent illness" because many people who suffer from this debilitating disease are totally unaware until it is too late.
Although fractures relating to osteoporosis are an important cause of poor health, disability and even death, they are preventable. In terms of determining fracture risk due to fragile bone in those who have not previously suffered a fracture, bone mineral density is the most readily quantifiable predictor.
As with many medical conditions, prevention is better than cure. In this regard, diet and physical activity have been shown to be important preventative measures in combating osteoporosis. Consumption of a healthy and balanced diet which includes appropriate intake of calcium and other essential vitamins and minerals throughout life, particularly in the critical growth stages, are important.
Regular exercise has been shown to have a positive effect on skeletal structure and strength in the same way that inactivity, immobilisation or a lack of mechanical loading, have a negative impact on bone health. Astronauts on extended space missions, for example, have been shown to suffer from significant bone loss, due to the lack of gravity and impact loading on the skeleton.
The American College of Sports Medicine emphasises the importance of maintaining a vigorous level of physical activity across the lifespan as being central to achieving and maintaining good bone health.
Specifically weight-bearing activity such as brisk walking, jogging, step aerobics, dancing and skipping has been shown to be effective in slowing the rate of decline or preventing bone loss.
One question that has received considerable attention is whether regular physical activity commencing in early life can lead to a positive and permanent change to the structure of the skeleton, which will enhance benefits to bone health throughout life and, in particular, the later stages.
Some evidence suggests that exercise-induced improvements in bone mass in children can be maintained into adulthood. It has been previously shown that impact exercises can lead to an improvement in bone mineral density in both boys and girls. While this remains to be fully determined, it would seem logical that engaging in appropriate physical activity during the critical growth phases may provide the best opportunity of achieving long-term benefits in bone health.
Based on the available scientific evidence, it is recommended that to promote good bone health and prevent the risk of osteoporosis and fractures in later life, men and women should engage in regular physical exercise, particularly of a weight-bearing nature which involves a degree of impact, throughout life.
• Dr Giles Warrington is a sport and exercise physiologist and lecturer in the School of Health and Human Performance at DCU