Prof. Shizue Masuki of the Institute for Biomedical Sciences and her team taught 679 middle-aged and elderly people (196 men, 483 women, average age 65 years) Interval Walking Training (IWT) for 5 months, and evaluated their physical fitness (peak aerobic capacity) and symptoms of lifestyle-related diseases before and after the program. Interval Walking Training is a method in which a person walks at 70% or more of their peak aerobic capacity for 3 minutes then at 40% of their peak capacity for the next 3 minutes, alternating between a strenuous and easy pace.
During the 5 months, there were those who did the IWT alternate fast and normal walks as instructed, a group who just walked fast all the time, and a group who walked slow and easy everywhere. As a result, physical fitness improvements and lifestyle-related disease improvement effects were proportional to the total time of fast walking per week, but not to the total time of normal walking or total time walked. To improve the health of middle-aged and elderly people it is important to take quick walks that feel a little strenuous. The length of time taken on easy walks unfortunately have no effect on fitness improvements or disease improvements.


See below for details.

Link to the Japanese Yahoo News Article
https://headlines.yahoo.co.jp/hl?a=20190906-00010000-medical-sctch

Link to the Paper
https://www.mayoclinicproceedings.org/article/S0025-6196(19)30473-2/fulltext