Source: BMJ  |  Posted 11 years ago

Men and women who take part in regular high impact physical activity may cut their risk of hip fractures compared with men and women who normally take part in moderate or low impact physical activity.

However, any interventions to increase such physical activity could be counterproductive in older people because of an increased risk of falls, declare Dr. Nicholas Wareham and colleagues with the Institute of Public Health, University of Cambridge, Cambridge, England.

Clinicians used associations between patterns of physical activity and ultrasound attenuation by the heel bone in a cross sectional, population based study among 2,296 men and 2,914 women, who were registered with general practices participating in European Prospective Investigation into Cancer (EPIC Norfolk) study. Patients were between the ages of 45 and 74 years

Dr. Wareham and colleagues point out: "Physical activity has been shown to be associated with bone density, but it is uncertain how the different aspects of this complex and multidimensional activity affect achievement of peak bone mass or its rate of decline in later life. Identifying the components of physical activity that are beneficial for a particular outcome is essential when designing preventive interventions, but the process is complicated by the difficulty of measuring the subdimensions of activity in epidemiological studies."

In the study they investigated low ultrasound attenuation by heel bone because it is associated with low bone mineral density, and this has been shown to be a predictor of higher risk of hip fracture.

Researchers found that men and women who were involved in regular, high impact physical activity, such as jogging, tennis, badminton and step aerobics, had a significantly higher ultrasound heel bone measurements than those who did not participate in such activity.

Men who reported participating in more than two hour per week of high impact activity had a 9.5 percent higher ultrasound attenuation than men who reported no activity of this type. Women who reported any high impact activity had a 3.4 percent higher ultrasound attenuation than those who reported none.

Researchers said that these findings can be translated into a 33 percent reduction of risk of hip fracture in men and a 12 percent reduction in women.

No effect was found with moderate or low impact physical activity. At the same time, among women who reported climbing more stairs, and watching less television, also had higher ultrasound measurements.

"These results support the development of preventive physical activity interventions that have an element of airborne projection and impact," researchers concluded. "Such interventions are inappropriate in an elderly cohort because they require a level of activity that might be poorly tolerated and have detrimental health effects at a population level.

"However, if these interventions were aimed at a population with an adequate degree of muscle strength and balance, such as younger women, they could reduce the rate of bone loss."