A recent study involving over 1,000 adults, with an average age of 33, indicated that following the recommended physical activity levels doesn’t sufficiently mitigate the risks associated with the more than 60 hours they spend sitting each week. To lower their risk of heart disease and slow down the aging process, it’s crucial for them to reduce their sitting time and increase the intensity of their workouts.
With long commutes, back-to-back video meetings, and evenings spent binge-watching shows, millennials are logging over 60 hours a week sitting down. This behavior could increase their risk of heart disease and accelerate signs of aging, according to new research from CU Boulder and the University of California Riverside.
The study, which surveyed more than 1,000 current or former residents of Colorado, including 730 twins, is among the first to examine how extended periods of sitting affect health indicators like cholesterol levels and body mass index (BMI) in younger adults.
It revealed that merely meeting the minimum exercise recommendations—around 20 minutes of moderate activity daily—does not sufficiently counterbalance the health risks of prolonged sitting.
“Our findings suggest that decreasing sit time during the day, increasing vigorous exercise, or a mix of both may be essential in lowering the risk of early aging in young adults,” explained the lead author of the study, Chandra Reynolds, a professor in the Psychology and Neuroscience Department and the Institute for Behavioral Genetics.
This research was published in the journal PLOS ONE, where Reynolds partnered with Ryan Bruellman, a PhD student in Genetics, Genomics, and Bioinformatics at UC Riverside.
Following the COVID-19 pandemic, Bruellman realized he and others his age were sitting more and wanted to understand the health implications of this trend.
“Many young adults believe they are immune to the effects of aging, thinking, ‘My metabolism is great; I don’t need to worry until I’m much older,'” noted Bruellman. “However, the choices made during this pivotal phase of life are crucial.”
A brief post-work walk isn’t enough
In their analysis, the authors evaluated participants aged 28 to 49, with an average age of 33, from CU’s Colorado Adoption/Twin Study of Lifespan Behavioral Development and Cognitive Aging (CATSLife), which has tracked twins and adopted individuals since childhood.
On average, the individuals reported sitting nearly 9 hours daily, with some sitting up to 16 hours. They engaged in roughly 80 to 160 minutes of moderate physical activity each week, alongside less than 135 minutes of vigorous exercise weekly. The researchers pointed out that these figures might be relatively better than national averages due to a generally active lifestyle in Colorado.
The investigation focused on two important indicators of heart and metabolic aging: total cholesterol/HDL ratios and BMI. The findings indicated that increased sitting correlates with appearing older, and merely adding some moderate activity on top of a sedentary day has minimal defensive effects.
Young adults who sat for about 8.5 hours daily and met or fell below current exercise recommendations could be classified as “moderate to high risk” for cardiovascular and metabolic diseases, the authors highlighted.
“A quick walk after work might not be sufficient,” Reynolds stated. “While this issue often becomes more apparent with age, we are starting to see these patterns in young adulthood.”
Engaging in vigorous activity had a positive counterbalancing effect.
For example, those who engaged in vigorous activities, like running or cycling, for 30 minutes each day demonstrated cholesterol and BMI measurements similar to individuals who were five to ten years younger and also spent a lot of time sitting but didn’t exercise.
However, even vigorous exercise was ultimately unable to completely offset the negative consequences of extensive sitting, the study concluded.
Same genes, varying lifestyles
Studying identical twins is particularly insightful as they share all their genes, simplifying the process of ruling out genetic influences on health variations and honing in on lifestyle changes.
When examining a group of twins with differing habits regarding sitting and physical activity, the researchers found that swapping out sitting for exercise was more effective at improving cholesterol levels than merely adding exercise to an already sedentary day.
Ultimately, researchers recommend aiming for a combination of both approaches.
Utilize standing desks, take regular breaks, and plan walking meetings to minimize sitting throughout the workday. When possible, strive for at least 30 minutes of rigorous activity daily, or embrace the “weekend warrior” lifestyle by committing to longer, intense workouts when time allows, suggested Bruellman.
He hopes this research sparks action among policymakers to reassess exercise guidelines and define how much sitting constitutes too much.
In the meantime, Reynolds encourages young adults to adopt habits now that will enhance their health in the long term:
“This is the perfect time to cultivate habits that will yield health benefits in the future.”
