‘Exercise snacks,’ or short bursts of activity, shown to improve fitness and strength

Short bursts of purposeful activity—like walking around the block or lifting light weights—may be the best way to develop an exercise habit. Light exercise also improves heart and muscle health, a study published Tuesday in the journal BMJ Sports Medicine found.

Less than half of US adults get enough aerobic activity and less than a quarter get recommended amounts of both aerobic and muscle strengthening exercises.

“When people are asked why they don’t exercise, the answers are almost always the same: no time and no motivation,” Miguel Angel Rodriguez, a clinical research doctoral student at the University of Oviedo in Spain who led the study, said in an email.

Rodriguez and his team measured how short periods of exercise throughout the day (which he calls “snacks”) affect cardiorespiratory and muscle fitness, as well as blood pressure and body composition in adults who do not exercise regularly.

The team collected data from seven randomized clinical trials that included people aged 18 to 80 years. The study involved more than 400 inactive people, about 70% of whom were women.

What is an effective workout snack?

Climbing stairs was most common among adults under 65, while exercises including tai chi, which strengthened lower body muscles, were more common among older adults.

They found that in adults under 65 years of age, these small bouts of physical activity significantly improved cardiorespiratory fitness. In older adults (65 years and older), snacking for workouts significantly improves muscle endurance. People were also highly likely to stick to these small exercises, with about 91% of adults and 83% of older adults doing them regularly.

“The greatest benefit comes early on, when someone goes from being inactive to being slightly active. That's where workout snacks can really help,” Rodriguez said.

The study did have limitations, including the fact that the seven clinical trials included used different data collection methods and had people exercise for varying durations, ranging from four to 12 weeks. For this reason, some of the benefits of moving may have been masked.

For example, contrary to the fact that Past studies have shown A new study finds that short bursts of activity do not appear to affect cardiometabolic health, such as body composition, blood pressure and blood lipid levels.

Lipids are fatty substances, including LDL (bad cholesterol), HDL (good cholesterol), and triglycerides, that serve important functions in the body but can be harmful if they accumulate in the blood.

“It was surprising that they didn't find any improvements in other markers of cardiometabolic health, unlike most other studies,” said Carol Ewing Garber, director of the Applied Physiology Laboratory and EXerT Clinic at Teachers College, Columbia University, who was not involved in the study. Cardiorespiratory health is a measure of how well the heart and lungs deliver oxygen to muscles during exercise and predicts a person's risk of developing heart disease and diabetes. A new study finds that short bouts of exercise improve cardiorespiratory fitness.

At the very least, regular, small, deliberate exercise will make everyday tasks like delivering groceries or making the bed much easier, Garber says.

“Most of us could probably find those five-minute chunks of time during the day to walk around the building we work in or walk up and down the stairs. We just don't think we can,” she said.

Short workouts cause changes in the body

“Perhaps the biggest benefit of starting a snacking routine for exercise is that it can help people who are sedentary build on those small changes,” said Dr. Tamannaah Singh, director of the Center for Sports Cardiology at the Cleveland Clinic.

“If you eat the same snacks for the same amount of time and with the same frequency, your body will get used to it. The body needs a challenge,” she said. “Snacks during exercise can set the stage for more intense workouts.”

Short workouts trigger key changes in the body that make intense workouts easier, Singh added. Within a couple of weeks after exercise, aerobic activity initiates cellular changes that increase the amount of plasma in the blood, which allows the blood to deliver more oxygen to the muscles and increases endurance.

Even mild aerobic activity strengthens the network of tiny blood vessels called capillaries that remove waste from the muscles. Consistent activity also increases the amount of energy cells can provide, she added. These changes make it easier to train for longer periods of time or at higher intensities.

“The main takeaway here is that anything is better than nothing, but that doesn't mean you should just exercise for three minutes,” Singh said. “Use this as a base, hopefully these workout snacks will make people want to snack.”

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