Middle-aged men who throw themselves into fitness can halve their risk of strokes, research suggests. Scientists said those with sedentary lifestyles had been able to transform their heart health in just seven years - protecting them three decades later.

Norwegian scientists tested the fitness of 1,400 men who were in their 40s and 50s at the start of the trial.

Most became less active as middle age set in, but one in three upped their efforts.

When they compared the group who boosted their fitness the levels the most with those who saw the greatest decline, they found startling differences.

Some of the best results were achieved among those who started out as couch potatoes.

The group with the biggest increase were 56 per cent less likely than the group which slowed down the most to suffer a stroke in later life.

Overall, one in eight had a stroke in the following 28 years, the study by the University of Oslo found.

Last week health officials warned of an “inactivity epidemic” with four in 10 adults failing to do even one 10 minute brisk walk a month.

They are particularly concerned about adults aged between 40 and 60, where poor lifestyles can have the greatest impact.