The way to invest in a healthier future?

Researchers from the Harvard School of Public Health found men who exercised regularly and vigorously early in their adult life had a lower risk.

Parkinson's is a progressive nervous disease occurring generally after age 50. It causes muscular tremors, rigidity, and slowing of movement.

Details of the study are published in the journal Neurology.

Leading an active and healthy lifestyle is generally beneficial in protecting against a number of diseases Robert Meadowcroft Parkinson's Disease Society

The researchers found the most physically active men cut their risk of developing Parkinson's by 50% compared with those who were the least likely to be active.

The effect was even more pronounced when strenuous physical activity was involved - those who regularly worked up a sweat had a 60% lower risk than those who never did.

The effect did not seem to hold good for women - although there was a small benefit from exercise, it was not statistically significant.

Long-term study

The 14-year study focused on more than 48,000 men and 77,000 women. During that time 387 (252 men and 135 women) were diagnosed with Parkinson's.

Participants were asked about activities such as walking, hiking, jogging, swimming and sport, but also about the number of stairs they climbed each day.

Lead researcher Dr Alberto Ascherio said: "These are intriguing and promising findings that suggest that physical activity may contribute to the prevention of Parkinson's."

Research on rats by the University of Pittsburgh published last year showed that exercise prevented degeneration of nerve cells that are normally destroyed by the disease.

These cells produce dopamine - a chemical which plays a key role in movement.

Robert Meadowcroft, director of the Parkinson's Disease Society, said: "Clearly leading an active and healthy lifestyle is generally beneficial in protecting against a number of diseases.