Short exercise 'snacks' improve blood sugar regulation after meals, U of T study finds

Whether you’re working from home or an office, the modern workday often involves spending hours sitting in front of a computer screen.

Not surprisingly, there’s a cost to such sedentary behaviour.

“Periods of prolonged sitting can be associated with elevated increases in the concentration of blood insulin, a hormone that regulates our blood sugar concentration following meals,” says Jenna Gillen, an assistant professor at the University of Toronto’s Faculty of Kinesiology & Physical Education (KPE).

“While increased insulin following a meal is normal, exaggerated spikes in the hormone can be an early sign of risk for metabolic diseases, like type 2 diabetes, as it suggests the body is working harder to lower blood sugar concentration after meals.” 

The good news is, we can do something about it and it involves snacking – on exercise. 

Gillen worked with a team of researchers from KPE and the Temerty Faculty of Medicine to investigate whether breaking up periods of prolonged sitting with short exercise “snacks” could improve blood sugar regulation throughout the day in men and women. Recently published in the Journal of Applied Physiology, their findings suggest that interrupting sitting with brief bouts of repeated chair stands or treadmill walking can reduce increases in post-meal insulin induced by too much sitting.

The study found that interrupting eight hours of prolonged sitting every 30 minutes with one minute of repeated chair stands or two minutes of treadmill walks lowered insulin concentrations following lunch. Short walks have previously been shown to be effective, but this was the first study to demonstrate that body-weight resistance exercise, such as the repeated chair stands, are just as effective for improving glycemic control in adults who engage in prolonged periods of sitting, but are otherwise healthy. 

“Importantly, repeated chair stands require no equipment or space beyond one’s sedentary area and may represent a practical strategy for mitigating cardiometabolic disease risk associated with prolonged periods of sitting,” says Gillen. “These findings are especially timely now when many individuals are looking for physical activity strategies that can be performed at home without the need for additional space or equipment.”

However, the researchers did not see a reduction in blood sugar concentrations throughout the day in response to the exercise snacks. This was surprising because studies in adults with obesity and/or impaired blood sugar regulation seen in type 2 diabetes have demonstrated that exercise snacks can lower post-meal spikes in blood sugar concentration. Gillen believes the explanation may lie in the fact that the participants of this study were relatively healthy with normal blood sugar concentrations.

“What this suggests is that exercise snacks in adults who engage in prolonged periods of sitting, but are otherwise healthy, are more likely to reduce the amount of insulin required to control blood sugar following a meal,” she says. 

Gillen emphasizes that, while exercise snacks are beneficial to anyone who spends a lot of time sitting during the day, they should not be interpreted as a replacement for daily moderate-to-vigorous physical activity. 

“That’s still very important,” she says.