Sheep yield osteoporosis clues

Osteoporosis sufferers could soon have sheep to thank for new types of therapy.

Scientists have demonstrated how even gentle, but regular, shaking of the limbs can ward off the weakening of the bones associated with the disease.

The researchers showed this by mechanically stimulating the hind legs of adult sheep for 20 minutes every day for a year, by standing them on a vibrating platform.

By the end of the study, the density of spongy bone in the animals' thighs was 34% higher than in sheep not receiving the treatment.

Large cost

Osteoporosis reduces the density and quality of bone, leading to weakness of the skeleton and an increased risk of fracture. The bones most at risk are the vertebrae, wrist, hip and pelvis.

In the UK alone, one in three women and one in 12 men are thought to be affected by the disease.

And it is a huge burden on the National Health Service - costing something like £900m a year to treat.

The design of some treatments could now benefit from the better understanding we have of how strain affects the bones.

Vigorous exercise

The tests on female sheep aged six to eight years old show that even small levels of strain on the body can play an important role in moderating the progression of the disease.

It was previously thought that only large strains, such as those induced by vigorous exercise - weight-training, running and jumping - could alter bone structure through a process of damage and repair.

But the very gentle, albeit high frequency, vibrations experienced by the sheep were about 500 times weaker than the sort of strain that would damage bone.

Clinton Rubin, from the State University of New York at Stony Brook, US, who undertook the study with colleagues, said the beneficial effects of just standing or trying to maintain a good posture should not be underestimated.

Health benefits

Reporting the sheep study in the journal Nature, Rubin's team write: "The strong bone-generating capacity of these small signals suggests that biomechanical intervention might help to strengthen bone in osteoporosis sufferers without the side effects associated with pharmacological treatment."

The UK's National Osteoporosis Society welcomed the research. "It follows similar studies carried out in recent years looking at the role of vibration on bone density in other animals," a spokesman said.

"We look forward to seeing if there are similar effects on humans.

"Weight-bearing exercise plays a part in the prevention of osteoporosis and regular exercise, such as brisk walking, skipping and running, also has other health benefits."