Alternating between fast and slow walking is particularly suited to people who do not do much regular exercise, according to experts. The Japanese interval walking trend, which has gone viral on social media, involves three minutes of fast walking followed by three minutes of slow walking, ideally for 30 minutes at a time.
Dr Kristian Karstoft, an associate professor at the University of Copenhagen who has studied the method, said: 'The fast walking pace is typically fast [enough] that you are not able to speak in long sentences. And then the slow intervals are so slow that you are able to recover.' He added that people often find it challenging to walk slowly enough during these intervals.
The approach is particularly suited to people prone to running injuries, as walking is less hard on the joints, or middle-aged or older adults who do not do much regular training. People who are already fit would need to jog or run for intervals to experience similar benefits.
While high-intensity interval walking has recently become popular on TikTok, the idea goes back more than 20 years when scientists in Japan began studying it in middle-aged and older adults. A Japanese study of 139 healthy participants with an average age of 63 found that those who did high-intensity interval walking on four or more days a week over five months increased their peak aerobic capacity, with improvements greater than those who undertook continuous moderate-intensity walking or no walking. The study also suggested it may reduce blood pressure and increase knee joint strength.
A small randomised control trial by Karstoft and colleagues found the approach could benefit people with type 2 diabetes, including by improving glycaemic control. 'Typically with interval walking, we’ve seen a gain in fitness level of around 15% to 20% compared to trivial or no improvements in fitness levels when subjects are doing the continuous walking [or no walking],' Karstoft said. 'We’ve seen improvements in body composition with an average weight loss during four to six months of training of around three to five kilograms, mainly due to fat mass.'
A review published by Karstoft and colleagues last year concluded that Japanese interval walking was a feasible and effective training regimen for older, fragile people, significantly enhancing fitness, muscle strength, and health markers.
