Thank you for downloading this program from BBC Radio 4. I'm Tim Halford.

Hello and welcome to More or Less, the balsamic vinegar on your statistical salad.

This week the cost of university tuition fees, and as the election begins to cast its long shadow,

we ask whether there's really such a thing as a safe seat.

But first let's talk about jogging, a convenient way to keep fit or a steady plot towards the

chill solitude of the grave. Because as the BBC rather unhelpfully reported this week, too much

jogging, as bad as no exercise at all. Which doesn't tell us a lot, the clue is in the phrase

too much. Too much of anything is excessive, that's not really a fact about jogging, but a fact

about the English language. Anyway, soon messages came flooding in to More or Less at bbc.co.uk,

some were skeptical and some were rather worried. I feel very healthy, I wonder how close to death

am I really? Asked Mania, who regularly jogs more than two and a half hours a week at a pretty good

pace. The BBC article was referring to a study published in the Journal of the American College

of Cardiology, so we decided to turn to somebody who'd analysed it.

Hello. Dr Alicia White of Bayesian, which is a consulting firm specialising in clinical evidence.

She analysed the study on behalf of the National Health Service behind the headlines website.

I asked her what the researchers had done. They assessed whether people jogged and if they did jog,

how much they jogged, how fast they jogged, how frequently they jogged, and then they also looked

at a group of people who were essentially sedentary, who didn't do very much exercise at all,

less than two hours a week of only very light exercise at most, and then it followed those people

up over about 10 to 12 years to see who died within that period, and then compared the different

groups of people to see if they could find any differences in the risk of death over that period

specifically. They were pulled into various groups, so the sedentary group and the light jogging,

...