Short bursts of focused activity – like walking around the block or lifting small weights – may be the best way to get into the exercise habit. Small portions of exercise also improve heart and muscle fitness, according to a study published Tuesday in BMJ Sports Medicine.
In the United States, less than half of adults get enough aerobic activity and less than a quarter get the recommended amount of aerobic and muscle-strengthening exercise.
“When you ask people why they don’t exercise, the answers are almost always the same, no time or no motivation,” Miguel Ángel Rodríguez, a doctoral student in clinical research at the University of Oviedo in Spain, who led the study, said in an email.
Rodríguez and his team measured how brief bursts of exercise spread throughout the day — which he calls exercise snacks — affected cardiorespiratory and muscular fitness, as well as blood pressure and body composition in adults who didn’t exercise regularly.
The team compiled data from seven randomized clinical trials including people aged 18 to 80. The study included more than 400 inactive people, about 70% of whom were women.
What is an effective exercise snack?
- An exercise snack was defined as vigorous physical activity lasting less than five minutes.
- The activity had to be performed at least twice a day, at least three days a week, for four to 12 weeks.
- The exercise was short and deliberate, like climbing stairs for the purpose of exercise.
Stair climbing was more common among adults younger than 65, while exercises, including tai chi, which strengthened lower body muscles, were more common among older adults.
They found that in adults younger than 65, these small acts of physical activity significantly improved cardiorespiratory fitness. For older adults –– those 65 and older –– exercise snacks significantly improved muscle endurance. People were also extremely likely to adhere to these small bouts of exercise –– about 91% of adults and 83% of older adults engaged in them regularly.
“The biggest benefits occur at the very beginning, when a person moves from inactivity to some activity. That’s where exercise snacks can really help,” Rodríguez said.
The study had limitations, including that the seven clinical trials included used different methods to collect data and asked participants to exercise for different lengths of time, between four and 12 weeks. For this reason, some of the benefits of moving may have been hidden.
For example, contrary to what previous research has found, the new study found that short bursts of activity did not appear to have an effect on cardiometabolic health, such as body composition, blood pressure and blood lipids.
Lipids are fatty substances, including LDL (bad cholesterol), HDL (good cholesterol) and triglycerides, which perform essential functions in the body but can be harmful if they accumulate in the blood.
“It was surprising that they didn’t see any improvement in these other markers of cardiometabolic health, unlike most other studies,” said Carol Ewing Garber, director of the Applied Physiology Laboratory and EXerT Clinic at Columbia University Teachers College, who was not involved in the study. Cardiorespiratory health measures the ability of the heart and lungs to deliver oxygen to muscles during exercise and predicts the risk of developing heart disease and diabetes. The new study showed that short bouts of exercise improved cardiorespiratory fitness.
At the very least, doing small amounts of deliberate exercise on a regular basis will make everyday tasks, like carrying groceries or making the bed, much easier, Garber said.
“Most of us could probably find those five-minute periods in our day, to walk around the building we work in, or go up and down the stairs. We just don’t think we can do it,” she said.
Short workouts create changes in the body
Perhaps the biggest benefit of starting a sports snack routine is that it can help inactive people reap the benefits of these small changes, said Dr. Tamanna Singh, director of the Cleveland Clinic Sports Cardiology Center.
“If you have the same snack, for the same length of time, at the same frequency, your body will get used to it. The body needs a challenge,” she said. “The exercise snack can be the start of a foundation for more intense exercise.”
Short workouts create key changes in the body that make it easier to intensify workouts, Singh added. A few weeks after exercising, aerobic activity triggers cellular changes that increase the amount of plasma in the blood, which allows the blood to deliver more oxygen to the muscles and prolongs endurance.
Even small amounts of aerobic activity strengthen the network of tiny blood vessels, called capillaries, that remove muscle waste. Consistent activity also improves the amount of energy cells can provide, she added. These changes make it easier to exercise for longer periods or at a higher intensity.
“The main takeaway here is that anything is better than nothing, but that doesn’t mean you should just do three minutes of exercise,” Singh said. “Use that as a basis, hopefully these exercise snacks will make people want to have an exercise meal.”
