Fast, slow, fast: why a Japanese walking exercise could be a step forward for health

If pumping iron or holding a plank leaves you cold, the latest exercise trend to dominate social media might put a spring in your step: Japanese interval walking.

- Nicola Davis

The idea is simple - alternate between three-minute bouts of fast and slow walking, ideally for 30 minutes at a time. That's it - a technique that can be tried as you pop out for a pint of milk.

"The fast walking pace is typically fast enough that you are not able to speak in long sentences," said Dr Kristian Karstoft, an associate professor at the University of Copenhagen, who has studied the method. "And then the slow intervals are so slow that you are able to recover," he said, adding that people often find it challenging to walk slowly enough during these intervals.

Putting the approach to the test, I hit the area around King's Cross, London. I begin striding out, as though late for a train. Three minutes later my watch beeps and I slow down, pottering along as if searching for a dropped earring. Another beep and I speed up once more, arms swinging.

I am slightly worried what passersby might think of my erratic pace - I suspect I look like I need the loo but dare not risk a jog. Already I am regretting attempting this without my two retrievers: if they were in tow I could blame my dawdling intervals on their lamp-post sniffing.

After 30 minutes I feel warm, but not exactly out of puff.