HMN 2026: How Think exercise can undo the effects of sitting all day? You may want to stand for this

A new Dalhousie study suggests improved fitness may not be enough to protect blood vessels from the effects of prolonged sitting. The study, published in the European Journal of Applied Physiology, examined whether 12 weeks of high-intensity interval training could protect blood-vessel function in the leg after two hours of uninterrupted sitting.

The researchers found the training improved aerobic fitness in healthy young adults. But even after participants became fitter, prolonged sitting still impaired markers of health in the popliteal artery, which runs behind the knee and supplies blood to the lower leg. The artery’s ability to relax and expand was compromised just as much as before training.

In addition, this sitting-induced impairment was consistent with that seen in participants in the control group who didn’t adopt additional fitness training.

How the study worked

The research team followed 21 healthy young adults. Eleven were assigned to a 12-week high-intensity interval training program, while 10 continued their usual physical activity.

Before and after the training period, participants completed a cycling test to measure changes in aerobic fitness. Researchers also used ultrasound to assess popliteal artery health before and after participants sat uninterrupted for two hours.

Why it matters

Past research and popular opinion suggest that regular exercise can offset long hours spent sitting. This study suggests it may not be that simple.

While exercise remains essential for cardiovascular health, the findings indicate that prolonged sitting may still affect blood vessel function in the legs, even among people who exercise.

“Many people assume a workout can compensate for a day spent sitting,” says Dr. Derek Kimmerly, senior author of the study and a professor of Kinesiology in Dalhousie’s School of Health and Human Performance. “But our findings suggest improved aerobic fitness alone may not protect blood vessels. Exercise is important, but you also need to break up long periods at a desk by moving around.”

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