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Studying the effect of brief periods of activity vs. sustained exercise

Can short bursts of activity make a difference in metabolic health?

Brisk walking
by Wendy S. Meyer

Fall 2018
Ask endocrinology researcher Audrey Bergouignan, PhD where she conducts her research and you might expect to hear the United States and France since she has academic appointments in both countries. What you might not expect to hear is that she has also studied the metabolic health of individuals from as far away as the North Pole to the International Space Station. Despite these exotic locales, Bergouignan also follows study participants right here on the Anschutz Medical Campus in the CCTSI’s Clinical and Translational Research Center (CTRC). She is currently leading a study in the CTRC on the effects of “microbouts” of activity on metabolic health, “Breaking Up pRolonged Sedentary Time” or BURST.  In addition, she just wrapped up another study on the effect of breaking up prolonged sitting on metabolic flexibility (METAFLEX), the results of which are now under review in several peer-reviewed journals.

Broad goals

“My research aims to understand the mechanisms by which sedentary behaviors contribute to the development and progression of metabolic diseases, such as Type 2 Diabetes, obesity or metabolic syndrome,” says Bergouignan. “With my research, I also hope to develop preventive strategies for the metabolic alterations induced by sedentariness—strategies that can be implemented in our daily lives.”
Bergouignan says that with her BURST study, she is looking at the effects over four weeks of either traditional exercise, which is defined as brisk walking 45 minutes a day, five days a week for four weeks. Or breaking the exercise up into nine bouts of five minutes of brisk walking, performed every hour. These small bursts of brisk walking are the “microbouts” of activity. 

Another way to describe the microbouts is, “Every hour, stand up, take a brisk walk, come back and sit. For four weeks,” Bergouignan says.

How the BURST study works

The study looks at the effect of these two interventions in overweight, obese, sedentary male and female participants. It will examine the effect on insulin sensitivity (how responsive your cells are to insulin) and also on glucose control. Participants will also spend time in the whole room calorimeter, which precisely measures a participant’s energy expenditure, or metabolism, in order to look at changes in the amount of fat, carbohydrates and protein the body uses as fuel. Through the study, Bergouignan hopes to learn if the sustained exercise or the microbouts of exercise result in a differential in the body’s metabolism.

Bergouignan will also look how much either type of exercise is changing or impacting the participants’ energy expenditure in “free living conditions” – or how participants function in their normal daily lives.  “There is more and more data, when you have someone overweight if you ask them to do exercise training, go on training, they compensate by spending more time in front of TV or ‘resting’,” she says. “That is not great because the benefit you are having from exercise is mitigated by increased sitting. We believe this may not happen with mircobouts of activity.”

In order to collect this data, the study equips subjects with activity monitors—one on their thigh that measures time spent sitting, lying, standing and stepping. Another monitor measures acceleration—telling the researchers precisely what kind of physical activity subjects are doing. Both monitors together characterize over 24 hours how much sitting or sedentary activity, walking fast, etc. the subjects are doing.

“The CTRC is one of the main assets that enables us to do all of these studies. Every aspect…the nurses are absolutely phenomenal, the whole room calorimeter, metabolic kitchen,” she says. “It would be impossible without them.”

Early results and public health implications

“I just looked at first results today, looking at primary data. We are observing that they [study participants] are spending less time sitting when they perform microbouts of activity vs. when they do one single, continuous bout,” Bergouignan says.

Though it is too early to talk about definitive results from these studies, Bergouignan’s earlier work informs her general message that it is not enough to only go to the gym and then be done moving. She says, “Sit less, move more!”

She aims to prove that sedentary behaviors are bad in the long run, therefore hoping to change occupational health and public health guidelines, to rethink our environments, and the active workstation. She says, “I hope to eventually move from the active workstation being a choice for an employee to a responsibility of the employer. If our data are confirming our hypotheses, this will be a successful story down the road.”


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