With long commutes, Zoom meetings, and hours spent streaming shows, many young adults now sit for over 60 hours a week.
A new study from the University of Colorado Boulder and UC Riverside shows that all this sitting time could raise the risk of heart disease and make young adults “age” faster.
Researchers studied over 1,000 young adults, including 730 twins, in Colorado to see how prolonged sitting affects health indicators like cholesterol and BMI (body mass index).
They found that meeting the minimum exercise recommendations—20 minutes of moderate exercise daily—isn’t enough to undo the negative effects of sitting too much.
“Just sitting less throughout the day and getting more intense exercise may be what’s needed to prevent early signs of aging,” said study leader Chandra Reynolds, a professor at CU Boulder’s Department of Psychology and Neuroscience.
Ryan Bruellman, a Ph.D. candidate at UC Riverside, was inspired to dig into this topic after noticing his own increased sitting during the COVID pandemic. “Young adults often think they’re safe from aging impacts,” he said. “But what you do in your 20s and 30s matters.”
The study, published in PLOS One, used data from participants between 28 and 49 years old, with an average age of 33. They found that on average, participants sat for almost nine hours daily.
Many reported only moderate weekly exercise, around 80 to 160 minutes, and vigorous exercise, like running or cycling, for less than 135 minutes. Colorado’s active lifestyle may mean these numbers are higher than national averages.
The researchers focused on two measures of “aging” in the body: cholesterol levels and BMI. They found that more sitting was linked to a higher risk of heart and metabolic diseases.
Even if someone took a short walk after work, it wasn’t enough to offset the effects of sitting all day. Those who sat over 8.5 hours per day and only met the basic exercise guidelines were at “moderate to high risk” for heart and metabolic issues.
However, vigorous activity helped somewhat. People who did 30 minutes of intense exercise daily, like running or cycling, had cholesterol and BMI levels similar to those of people five to ten years younger. Yet, even with this high level of exercise, they couldn’t fully avoid the negative effects of too much sitting.
The study also looked at identical twins with different sitting and exercise habits. Twins who replaced sitting time with exercise had better cholesterol levels than those who simply added exercise on top of sitting all day.
For a healthier lifestyle, researchers suggest using a standing desk, taking frequent breaks, organizing walking meetings, and aiming for 30 minutes of vigorous activity daily. If that’s not possible, longer, intense workouts on weekends can help too.
Bruellman hopes this study will prompt policymakers to set clearer guidelines on how much sitting is too much. Meanwhile, Reynolds encourages young adults to start building healthy habits now to benefit their long-term health.
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