A four-month randomized clinical trial found that adults with abdominal obesity who completed one 75-minute interval-walking session each week achieved reductions in body fat and waist circumference comparable to those exercising for 25 minutes three times weekly.
By yourNEWS Media Newsroom
Adults struggling to fit several workouts into their weekly schedules may be able to obtain similar body-fat benefits by concentrating the same amount of interval walking into a single session, according to a randomized clinical trial from researchers at the University of Hong Kong.
The study, published in Nature Communications, found that one 75-minute interval-walking session per week produced improvements in body fat percentage, total fat mass and waist circumference comparable to three 25-minute sessions spread throughout the week.
Researchers at the University of Hong Kong’s School of Public Health enrolled 315 adults with abdominal obesity and followed them through a 16-week exercise program.
Participants were randomly divided into three groups. One completed a single 75-minute interval-walking workout each week, another performed three 25-minute sessions weekly, and a control group did not participate in the exercise program.
Interval walking involved periods of very fast walking alternated with shorter recovery periods rather than maintaining the same walking pace throughout the session.
The trial was conducted between September 2021 and September 2024.
Researchers assessed participants before the program began, immediately after the 16-week intervention and again four months after the exercise program ended.
Body composition was measured using bone-density scanning technology capable of distinguishing fat and lean tissue. Researchers tracked total body fat mass, overall body fat percentage and waist circumference.
At the end of 16 weeks, both exercise groups experienced similar improvements across those measurements.
The results suggest that, at least for the outcomes examined in the trial, accumulating 75 minutes of weekly interval walking in one session could produce effects comparable to dividing that exercise into three separate workouts.
Professor Parco Siu Ming-fai, the study’s lead researcher, said the findings could be particularly useful for people whose work, family or other obligations make exercising several days each week difficult.
“While thrice-weekly interval training remains a commonly recommended approach for the therapeutic management of obesity, our findings show that once-weekly interval training offers similar benefits and represents a practical exercise strategy,” Siu said.
“For many adults with central obesity who struggle to balance work, study, family and other commitments, time constraints are a primary barrier to exercising multiple days per week,” he added.
Abdominal obesity is characterized by excess fat accumulating around the midsection, including visceral fat stored around internal organs.
High levels of visceral fat are associated with increased risks of Type 2 diabetes, cardiovascular disease and other health problems.
The researchers found no significant improvements in participants’ blood pressure or cholesterol during the intervention. They said that may be because those measurements were already within normal ranges for many participants when the study began.
Some of the benefits also diminished after the structured exercise program stopped.
Four months after the intervention ended, reductions in waist circumference were still detectable, but much of the advantage in overall fat loss and body weight had faded.
That finding suggests that maintaining physical activity may be important for preserving changes achieved during a temporary exercise program.
The researchers concluded that once-weekly interval training could provide a feasible alternative for adults unable to schedule workouts on several different days.
The results also add to previous research suggesting that the total amount and intensity of exercise may sometimes be more important than how frequently that exercise is divided throughout the week.
Interval exercise has been studied for its ability to produce physiological adaptations in relatively limited amounts of time. Research has found that higher-intensity activity can increase catecholamines, hormones that help mobilize stored fat for energy.
Moderate activities such as brisk walking have separately been associated with improved insulin sensitivity and reductions in visceral fat.
Walking itself has also been linked in previous research with lower mortality risk, even when people perform relatively modest amounts of regular activity.
The new findings do not mean that 75 minutes of weekly walking meets all established physical-activity recommendations.
The National Health Service in the United Kingdom recommends that adults obtain at least 150 minutes of moderate-intensity physical activity each week, with brisk walking listed as one way to accumulate that exercise.
The trial instead examined whether different schedules containing the same 75 minutes of weekly interval walking produced different effects on body fat among adults with abdominal obesity.
Approximately 66% of adults in the United Kingdom are classified as overweight or living with obesity.
Obesity is associated with conditions including Type 2 diabetes, cardiovascular disease and breathing disorders and costs the National Health Service more than 11 billion pounds annually.
The study’s results indicate that people unable to exercise several days each week may still benefit from setting aside one longer period for structured interval walking, although maintaining activity over time remains important for preserving the gains.
Rather than showing that exercise frequency does not matter under all circumstances, the trial found that for body fat and waist measurements in this group of adults, one 75-minute weekly session performed comparably to three 25-minute sessions over the 16-week program.
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