Long distance running could protect against brittle bones in later life, scientists have found.
A study discovered those who ran marathons and 10km races had stronger bones than people who did no exercise – an effect that was seen in both male and female runners.
And the greater distance the person ran, the denser their bones – suggesting marathons can stave off weak bones in old age.
Researchers said weight-bearing exercise or high impact moves like jumping can boost bone strength.
The quality and strength of our bones is determined by their mineral density- the amount of calcium and other nutrients – which depends on factors such as sex, age, race and diet.
People with low bone mineral density are more prone to osteoporosis, in which bones become brittle, fragile and weak and are more likely to break.
From the age of 35 we begin losing bone density naturally – with women losing more than men due to hormonal changes after the menopause.
However, it has long been known that regular exercise can increase bone density.
As part of the study, researchers analysed the calcaneus – a bone in the foot that forms the heal – in 122 marathon runners and 81 half marathon and 10km runners.
They compared this to those of a control group of sedentary individuals of a similar age.
The tests were performed on both the left and right feet of the people involved.
The scientists said training for endurance races is effective in producing physical changes in the physical properties of the calcaneus, ie strengthening it.
Professor Beatriz Lara, of Camilo Jose Cela University in Madrid, who carried out the research, said: ‘The results showed the endurance runners had a greater stiffness index than the sedentary individuals.
‘It was also possible to confirm a dose-response relationship – meaning greater amounts of training correspond to a greater improvement in the mineral density of the calcaneus.’
Therefore, running can prevent the progressive decline in bone mineral quality that occurs with age, the researchers said.
Boosting bone density can also be achieved by weight-bearing exercise or high impacts such as jumping.
Professor Lara said: ‘Sports such as swimming or skating – in which body weight or impact loading are reduced – do not generate high osteogenic benefits.
‘Nevertheless the effect that endurance running training may have on our bones is not yet known – while it does not entail high impacts, it does require running long distances.’
The study was published in the European Journal of Applied Physiology.