In an era defined by lengthy commutes, workdays dominated by virtual meetings, and evenings dedicated to streaming and social media, millennials now spend over 60 hours per week seated, a habit that could increase their risk of heart disease and accelerate ageing signs. This insight comes from new research conducted by the University of Colorado Boulder and the University of California Riverside.
The investigation involved more than 1,000 individuals who were either current or former residents of Colorado, including 730 twins. It is one of the pioneering studies to examine the effects of prolonged sitting on health markers such as cholesterol levels and body mass index (BMI) among young adults.
The findings revealed that more than merely adhering to the minimum recommended physical activity guidelines, which suggest about 20 minutes per day of moderate exercise, is required to negate the risks associated with extensive daily sitting.
Chandra Reynolds, the study’s senior author and a professor in the Department of Psychology and Neuroscience and the Institute for Behavioral Genetics, emphasized the necessity of either reducing sitting time or engaging in more vigorous exercise or both to mitigate the risk of premature ageing in early adulthood.
The study, published in PLOS ONE, saw Reynolds collaborate with Ryan Bruellman, the lead author and a doctoral candidate at UC Riverside’s Department of Genetics, Genomics, and Bioinformatics. Post-COVID, Bruellman observed increased sitting habits among his peers, prompting a deeper exploration into its potential long-term effects.
Bruellman noted that young adults often overlook the impacts of ageing due to their robust metabolism, underestimating the significance of their lifestyle choices during these formative years.
Their analysis included participants aged between 28 and 49, with an average age of 33, from the Colorado Adoption/Twin Study of Lifespan Behavioral Development and Cognitive Aging (CATSLife), which tracks twins and adopted individuals from childhood.
On average, these individuals reported sitting for nearly nine hours daily, with some reporting as much as 16 hours. Their weekly exercise ranged from 80 to 160 minutes of moderate activity and less than 135 minutes of vigorous exercise. While seemingly active, these figures likely paint a healthier picture than the national average, buoyed by Colorado’s typically active lifestyle.
The research team focused on two primary indicators of heart and metabolic health: the ratio of total cholesterol to high-density lipoprotein and BMI. The study concluded that the more an individual sat, the “older” they appeared regarding these health metrics. Moreover, adding moderate activity to a predominantly sedentary day did little to alleviate these effects.
Interestingly, young adults who sat for approximately 8.5 hours a day and engaged in minimal to no exercise were at a “moderate to high risk” for cardiovascular and metabolic diseases, according to the study.
The team also discovered that vigorous physical activities, such as running or cycling for 30 minutes daily, could significantly improve cholesterol and BMI levels, making individuals appear five to ten years younger than their less active counterparts.
However, even vigorous activities couldn’t completely offset the adverse effects of prolonged sitting, suggesting that the combination of less sitting and more intense physical exercise was more beneficial.
The study particularly highlighted the utility of identical twins in isolating lifestyle factors from genetic influences, showing that replacing sitting time with exercise was more effective in improving health outcomes than merely adding exercises to a sedentary routine.
The findings underscore the importance of reducing sitting time—through measures like standing desks, taking regular breaks, and organizing walking meetings — and engaging in substantial vigorous exercise.
Bruellman hopes this research will prompt a reevaluation of physical activity guidelines to address excessive sitting. Meanwhile, Reynolds advises young adults to establish healthy habits to ensure long-term benefits, suggesting that the current moment is crucial for setting the foundations of lifelong health.
More information: Ryan Bruellman et al, A twin-driven analysis on early aging biomarkers and associations with sitting-time and physical activity, PLOS ONE. DOI: 10.1371/journal.pone.0308660
Journal information: PLOS ONE Provided by University of Colorado at Boulder
