Interval walking explained: what trials show about the three-minute fast, three-minute slow routine

A walking routine devised in a Japanese university laboratory nearly two decades ago has become one of the most searched fitness ideas of 2026. Under the nickname “Japanese walking,” it saw a 2,968% increase in search interest over the past year, according to an analysis cited by Jack McNamara, an exercise physiologist at the University of East London, writing in The Conversation in March 2026. In August 2026 the American television weatherman Al Roker told his followers he had tried it. “It’s interval walking. 3:00 of a hard walk; where you have trouble holding a sustained conversation. Then 3:00 of a normal walk. It let me walk further,” Roker wrote.

Fitness trends usually have thin evidence behind them. This one is different in a specific way: it began as a randomized trial. What follows is what that trial and its successors found, and what they did not test.

What interval walking is

What social media calls Japanese walking is a well-established form of interval walking training developed by researchers in Japan. The researchers were at Shinshu University, and Hiroshi Nose is the senior author of their original trial.

Interval training of any kind alternates hard effort with recovery. The idea is that short hard bouts push the heart, lungs and muscles further than a steady pace can, and the recovery periods make the hard bouts tolerable. Runners and cyclists have trained this way for decades. The Shinshu group’s contribution was to adapt it for older people who were not athletes, using walking alone.

Their prescription was precise. Participants were told to repeat 5 or more sets of 3-minute low-intensity walking at 40% of peak aerobic capacity, each followed by 3 minutes of high-intensity walking above 70% of peak aerobic capacity, on four or more days a week. Peak aerobic capacity is the most oxygen a person can use during all-out exercise, the standard laboratory measure of fitness. Seventy percent of it is a brisk, effortful walk.

That works out to at least 30 minutes a session. “It challenges the cardiovascular system. It’s like hitting the gas and then backing off, which helps to improve heart health, lung capacity and caloric burn,” Jeanne Doperak, a sports medicine physician in Pittsburgh, told TODAY.

What the original interval walking trial found

The trial ran for five months in 2004 and was published in 2007. Its participants, 60 men and 186 women with an average age of 63, were randomly divided into 3 groups: no walking training, moderate-intensity continuous walking training, and high-intensity interval walking training.

The comparison group mattered. People in the continuous group were given a conventional goal, walking at about half their peak capacity and using a pedometer to verify that they took 8000 steps or more per day for 4 or more days per week. So the trial pitted intervals against the kind of walking that public health advice had long promoted. The interval group wore accelerometers, devices that record movement, so the researchers could check how hard they walked.

The interval group came out ahead on the measures the researchers chose. In that group, isometric knee extension increased by 13%, isometric knee flexion by 17%, peak aerobic capacity for cycling by 8%, and peak aerobic capacity for walking by 9%. Isometric means measured against a fixed resistance, and knee extension and flexion are the strength of the muscles at the front and back of the thigh. In McNamara’s summary of the trial, the interval group showed greater improvements in thigh muscle strength, aerobic capacity and blood pressure than a steady-pace group.

The authors’ conclusion was hedged. High-intensity interval walking, they wrote, may protect against age-associated increases in blood pressure and decreases in thigh muscle strength and peak aerobic capacity.

One number in the report gets little attention online. The training targets were met by 11 of 19 men and 31 of 68 women in the high-intensity interval walking training group. That is 42 of 87 people, or 48%. In the continuous walking group 51 of 75, or 68%, met theirs. Fewer than half of those asked to do interval walking kept it up at the prescribed level.

What later interval walking studies added

The Shinshu group scaled the idea up. In a second study, 246 males and 580 females, aged about 65 on average, followed the routine for four months, and 666 completed all the measurements. The researchers sorted them into three groups by starting fitness, low, middle and high. Fitness and thigh strength rose, and weight, body fat, blood pressure and blood glucose concentration decreased in all groups, the researchers reported. The people who were least fit at the start changed the most: the changes were greatest in the low group for both sexes. That study had no comparison group that did not train. Everyone did interval walking, and measurements were taken before and after.

A third analysis asked which part of the routine does the work. Among 679 people who completed five months, improvement tracked the time spent walking fast and not the total time spent walking. Fitness and a composite score of lifestyle-related disease risk improved as fast walking time per week increased up to 50 min/wk but plateaued above this time. Improvement was not positively correlated with slow or total walking time per week. Fifty minutes of fast walking a week is slightly less than the 60 minutes the protocol delivers if followed on four days.

The most informative independent test came from Copenhagen, in people with type 2 diabetes. Subjects with type 2 diabetes were randomized to a control (n = 8), continuous-walking (n = 12), or interval-walking group (n = 12). Training groups were prescribed five sessions per week (60 min/session), and the two walking groups were matched so that they expended the same energy.

The matching is what makes the result interesting. With total effort held equal, aerobic fitness rose by 16% in the interval group and did not change in the steady walkers. Body mass and adiposity (fat mass and visceral fat) decreased in the interval-walking group only. Visceral fat means fat stored around the abdominal organs. Glucose levels measured by continuous monitor fell in the interval group as well. The Danish authors concluded that interval walking is superior to energy expenditure-matched continuous walking for improving physical fitness, body composition, and glycemic control. Glycemic control means the regulation of blood sugar.

It was a small trial, with 12 people per walking group, and both groups walked five hours a week, far more than the Japanese protocol.

How interval walking compares with ordinary walking

Ordinary walking has strong evidence of its own. The largest analysis of step counts pooled 15 studies covering 47,471 adults, among whom 3,013 died during follow-up. Taking more steps per day was associated with a progressively lower risk of death from any cause, up to a level that varied by age. The association kept strengthening among adults aged 60 years and older with increasing number of steps per day until 6000-8000 steps per day, and among younger adults until 8,000 to 10,000.

That analysis also looked at pace. Once total steps were taken into account, the link between faster stepping and survival weakened. It remained for the pace of a person’s fastest 30 or 60 minutes of the day and disappeared for total time spent walking briskly.

The two bodies of evidence measure different things. The step studies count deaths over years and say that walking more is associated with living longer. The interval trials measure fitness and strength over months and say that walking faster in bursts improves them more than walking steadily. Neither shows that intervals add years.

Official guidance leaves room for both. World Health Organization guidelines call for 150 to 300 minutes of moderate activity, or 75 to 150 minutes of vigorous activity, or some equivalent combination of moderate-intensity and vigorous-intensity aerobic physical activity, per week. Whether a week of interval walking meets that target depends on how many sessions are done and how hard the fast portions are. The guidelines recommend regular muscle-strengthening activity for all age groups too, which walking of any kind does not fully replace.

McNamara, reviewing the trend, reached a measured verdict. Japanese walking appears to be a useful upgrade to a regular walking habit, McNamara wrote, but it’s not the only way to get moving.

Where the interval walking evidence falls short

Most of the research comes from one group. The original trial and both large follow-up studies were run by the Shinshu University researchers who designed the method, and the larger studies had no comparison group. People who enroll in and complete a five-month walking course are not typical of the population.

Adherence is the practical weak point. In the original trial fewer than half of the interval group met the target. McNamara notes that roughly 22% of participants dropped out of the interval arm, more than in the steady-pace group. Others stayed in the trial without reaching the target. Results in those who persisted may overstate what an average person assigned to the routine would gain.

The outcomes are intermediate ones. Strength, aerobic capacity, blood pressure and blood sugar are worth improving, and they are stand-ins for the events that matter. As McNamara put it, no study has yet linked Japanese walking directly to living longer.

The studies were short, four to five months, and most participants were Japanese adults in their sixties. Claims that the routine builds bone or burns extra calories afterward, which appear in popular coverage, were not tested in these trials.

Brisk walking raises heart rate and blood pressure during the effort, and whether that is suitable for someone with a heart condition or joint problems is assessed by their doctor.

Interval walking improved fitness more than steady walking in a trial of 246 older adults, where it also raised leg strength, and in a small diabetes trial, while fewer than half of those assigned to it kept it up and no study has followed walkers long enough to count heart attacks or deaths.