Brief bouts of physical activity — often called “exercise snacks” — can significantly improve cardiorespiratory fitness in adults who lead largely sedentary lifestyles, according to a new review published in the British Journal of Sports Medicine.

Researchers from the University of Oviedo, Spain, led by Miguel Ángel Rodríguez, analyzed 11 randomized controlled trials involving 414 participants to study the impact of short, structured exercise sessions on physical fitness and metabolic health. These “exercise snacks” were defined as five-minute or longer workouts, performed at least twice daily, three times or more per week, for two weeks or longer.

The review found that these mini-workouts significantly enhanced heart and lung function (cardiorespiratory fitness) among physically inactive adults and also improved muscular endurance in older adults. The findings showed a moderate level of certainty for improvements in overall fitness and a lower level of certainty for muscle endurance.

However, the researchers found no major changes in body composition, blood pressure, or cholesterol levels — suggesting that while short bursts of exercise improve fitness, they may not replace longer workouts when it comes to broader metabolic health benefits.

Notably, adherence to these short exercise routines was high — with over 90% compliance, indicating that brief, frequent workouts may be easier for inactive individuals to maintain.

“Based on rigorous evidence, these findings support the idea that short, structured bouts of exercise can effectively improve cardiovascular fitness in people who otherwise struggle to find time for long workouts,” the authors wrote.

Experts say the findings could reshape how people approach fitness — especially for those who find it difficult to dedicate long periods to exercise. Even a few minutes of activity, spread throughout the day, can make a measurable difference to heart health.