Quick ‘activity snacks’ help maintain muscle mass while sitting all day

TORONTO, Ontario — Who says a snack has to refer to chips or cookies? Spending most of the day stationary is unavoidable for many these days, but researchers from the University of Toronto say periodic activity “snacks” may help maintain both muscle mass and quality.

What exactly is an “activity snack”? Daniel Moore, an associate professor of muscle physiology at the Faculty of Kinesiology & Physical Eduction (KPE), explains just two minutes of walking or body weight sit-to-stand squats is enough to constitute a fitness snack. These short bursts of motion help our bodies use more of the amino acids gained from meals to build muscle proteins.

“We know that prolonged sedentary periods impair the body’s ability to filter sugar from the blood following a meal,” says Moore, who heads the Iovate/Muscletech Metabolism & Sports Science Lab at KPE, in a university release. “However, breaking up this sedentary period with brief bouts of activity such as two minutes of moderate intensity walking or rising and lowering 15 times from a chair (i.e. body weight squats), can improve the way our body clears sugar from our meals.”

The research team set out to understand if breaking up prolonged periods of sitting, a fact of life across countless offices and workplace settings, would increase the ability of muscles to utilize amino acids (the building blocks of protein) gained from food to help repair or replace old or damaged proteins.

“This is critical to ensure the body has an adequate quantity and quality of muscle,” Prof. Moore adds.

Standing up every 30 minutes can improve protein synthesis

A total of 12 people took part in this study (seven men, five women). Across three trials lasting seven and a half hours, the participants had to sit for a prolonged period before interrupting that sedentary behavior every 30 minutes with short bouts of walking or body weight squatting. The exercises helped increase dietary amino acid efficiency in reference to muscle protein synthesis — the process by which the body repairs or replaces old or damaged proteins.

“This is significant because prolonged periods of low muscle activity – from sitting, wearing a cast or bed rest – is associated with a loss of muscle mass that occurs in parallel with, or because of, an inability of our muscle to build new proteins after we eat a protein-containing meal,” Prof. Moore explains.

“Our results highlight the importance of breaking up prolonged sedentary periods with brief activity snacks. We believe they also highlight that moving after we eat can make our nutrition better and could allow more dietary amino acids from smaller meals or lower quality types of protein to be used more efficiently,” the researcher concludes.

The study is published in the Journal of Applied Physiology.

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