Benefits to longevity of walking hit a plateau at around 5,000 to 7,000 steps per day for older Japanese people, a study has found.

This is equivalent to about an hour of walking, which the team says is the optimal duration for Japanese people's longevity.

The findings by the team, which includes Waseda University assistant professor Daiki Watanabe, were published in the digital edition of the U.S. journal Medicine & Science in Sports & Exercise in early February.

The team in 2013 studied how people's death risk is related to the number of steps they walk a day, using data from 4,165 men and women age 65 or over in Kameoka, Kyoto Prefecture. They were followed up for up to four years, during which 113 of them died.

For those who walked fewer than 5,000 steps per day, an extra 1,000 steps lowered their death risk by 23%. This translates to an increase of nine to 10 months in their life span.

However, walking more than 5,000 to 7,000 steps provided no additional longevity benefits.

For those with frailty, walking fewer than 5,000 steps per day had almost no impact on their death risk, while walking more than that reduced their death risk significantly.

Also, the more steps they walked over 7,000 steps, the more their death risk decreased.

The study did not look into the causes of death, so the team does not know why the longevity benefits of walking were different between those with and without frailty.

Physical activity such as walking is said to improve people's heath and extend their lifespan, but the optimal number of walking steps for Japanese people's longevity was unknown.

"I hope elderly people who have had fewer opportunities to go out due to the spread of the novel coronavirus will try to walk about an hour per day," Watanabe said.