By Stephen Beech via SWNS
Too much time sitting “significantly harms” even the health of active young people, warns new research.
Prolonged periods seated raises the risk of heart disease and obesity for physically fit adults, say American scientists.
They also found that current exercise guidelines are “insufficient” to offset the negative effects of too much time spent sitting down.
While much research on aging involves people in their 60s, the new study focused on younger adults.
Researchers from the University of California, Riverside, (UCR) and the University of Colorado, Boulder, looked at health data from more than 1,000 men and women in Colorado whose average age was 33.
The findings, published in the journal PLOS One, show that sitting for eight or more hours per day increases cholesterol ratios and BMI, even in physically active people.
Cholesterol ratios, which combine triglyceride and cholesterol levels to gauge heart disease risk, and body mass index (BMI), a measure of body fat, are early indicators that can predict more severe health issues.
Lengthy sitting sessions can raise even a younger adult’s BMI by nearly a full point compared to people who sit only a few hours during an average day, according to the study.
Research leader Ryan Bruellman said: “Though unhealthy diet and smoking play a major role in increasing BMI, the full-point jump we saw in the data was just due to sitting alone.,”
He explained that sitting for eight or more hours a day also tended to move men in their early 30s and women in their mid-30s from healthy to higher-risk cholesterol ratios.
Because many of the study participants already had cholesterol levels on the high end of optimal, the researchers say too much sitting made the difference between no and moderate cardiac risk.
While current U.S. Department of Health and Human Services guidelines recommend 2.5 hours of moderate exercise or 75 minutes of vigorous exercise weekly, the team said those levels appeared “inadequate” for people who sit extensively throughout the day.
Bruellman, a doctoral candidate in UCR’s Department of Genetics, Genomics and Bioinformatics, said: “People don’t often think about how much time they spend sitting, especially in their 20s and 30s, but it matters.”
Participants in the study self-reported their weekly sitting habits, including time spent sitting at work, during leisure activities, and while traveling.
They also detailed their physical activity, categorized as “moderate” or “vigorous”.
Moderate activities, such as brisk walking, allow for conversation, while vigorous activities – like running – leave participants breathless, according to the researchers.
Biological markers, such as cholesterol ratios – a key indicator of cardiovascular risk – and BMI, were measured in person.
The findings showed that reducing sitting time significantly improves health outcomes.
But for those unable to limit their sitting time, increasing the intensity and duration of physical activity is crucial.
Doubling the recommended amount of weekly exercise – either five hours of moderate activity or 2.5 hours of vigorous activity – was more effective at lowering health risks associated with prolonged sitting.
The research team also explored the role of genetics and environment by studying identical twin pairs. This unique approach helped isolate behavioral choices as the key factor in health differences.
Among twins, those who reduced their sitting time or engaged in higher levels of vigorous activity consistently showed healthier cholesterol ratios and BMIs than their siblings who sat longer or exercised less.
Bruellman said: “This study makes it clear: if you sit for long periods, the standard exercise recommendations are not enough.
“All adults, even the younger ones, need to move more, and exercise harder, to counteract the impact of sitting.”
While reducing sitting time remains the most effective method, the researchers hope to emphasize that all is not lost for people with sedentary jobs or lifestyles.
They say increasing the intensity and duration of exercise – especially vigorous activities – can help offset the damage.
The team found that just 10 minutes of vigorous exercise for every additional hour of sitting “significantly mitigated” the negative effects of too much time spent sitting down.
They hope their findings show that is not only the duration but also the intensity of physical activity that makes a difference, particularly for those with predominantly sedentary routines.
Bruellman added: “Young adulthood is a critical time to establish healthy habits.
“If you don’t prioritize movement now, it only gets harder as life fills up with more responsibilities.”
