A recent study published in The Journal of Nutrition, Health and Aging underscores the significance of limiting sedentary behaviors and being physically active to improve metabolic health among older adults, whether they are physically active or not.
Background
Physical activity is widely acknowledged as a cornerstone of cardiovascular health. Global guidelines recommend at least 150 minutes of moderate-to-vigorous physical activity (MVPA) per week, alongside efforts to reduce sedentary time, particularly for older adults. This combination is considered vital for improving metabolic health and reducing the risk of metabolic syndrome, which includes conditions like insulin resistance, abdominal obesity, dyslipidemia, and hypertension. These conditions increase the risk of cardiovascular diseases and type 2 diabetes, particularly in older adults.
Metabolic syndrome has a profound impact on health, and older adults, who often engage in more sedentary behavior, are especially at risk. While the benefits of regular physical activity are well-documented, it remains uncertain whether reducing sedentary behavior alone can independently improve metabolic health. This study sought to explore the effects of sedentary time and physical activity on metabolic risk among older adults.
Study Design
The study used data from the NU-AGE study, a randomized controlled trial designed to assess the effects of a healthy diet on biomarkers of aging in older European adults. This research analyzed baseline data from 871 community-dwelling adults aged 65 to 79 years from four European countries. Participants’ physical activity levels and sedentary behavior were measured using accelerometers worn during waking hours. These data were used to categorize the participants’ sedentary behavior into three groups: low, medium, and high, based on the percentage of time spent sitting during the day.
The researchers assessed five metabolic risk factors (waist circumference, blood pressure, blood glucose, triglycerides, and HDL cholesterol) and created a continuous metabolic syndrome risk score (cMSy). They also evaluated participants’ healthy eating habits using food records.
Study Findings
On average, the participants spent 60% of their waking hours sitting, 37% in light-intensity physical activity, and only 3% in moderate-to-vigorous physical activity. The study found that those who spent the least time sitting (low sedentary behavior group) were twice as likely to engage in moderate-to-vigorous physical activities compared to those who sat the most.
The analysis revealed that those who spent less than 8.3 hours a day sitting had a significantly lower risk of metabolic syndrome, as measured by the cMSy score. This was true for both physically active and inactive participants. On the other hand, no significant difference was observed in metabolic risk between participants in the medium and high sedentary behavior groups, indicating that sitting more than 8.3 hours per day may represent a critical threshold for increased metabolic risk.
Interestingly, even among the physically inactive participants, those who spent less time in sedentary behaviors experienced better metabolic health, suggesting that reducing sedentary behavior may provide benefits even for those not meeting the physical activity guidelines. Moreover, the benefits of reducing sedentary behavior were evident regardless of dietary habits, further highlighting the importance of minimizing time spent sitting.
Study Significance
The study found that a shorter duration of sedentary behavior was associated with a lower risk of metabolic syndrome, regardless of whether the individual was physically active or adhered to healthy eating habits. This suggests that sitting less is beneficial for metabolic health, regardless of one’s overall physical activity level.
The research also showed that light-intensity physical activity, which can occur during the reduction of sedentary time, might offer meaningful benefits for metabolic health. This is particularly encouraging for older adults who may struggle to meet the recommended levels of moderate-to-vigorous physical activity. In fact, the study highlights that light-intensity activities, even if not reaching moderate intensity, can still improve metabolic outcomes.
Moreover, the study reinforced that sedentary behavior is an independent risk factor for metabolic syndrome. Even after adjusting for physical activity and diet, the duration of time spent sitting was significantly linked to metabolic risk.
The findings were consistent across four different European countries, reinforcing the global applicability of the results. However, the study had limitations, such as not including adults with frailty, dementia, or severe heart disease, which may limit the generalizability of the findings. Additionally, the cross-sectional design of the study means that it cannot establish causality between sedentary behavior and metabolic risk.
Conclusion
In summary, this study emphasizes the importance of reducing sedentary behavior for improving metabolic health, especially in older adults. The findings suggest that sitting less, even without engaging in extensive physical activity, can lower the risk of metabolic syndrome. However, the benefits are maximized when sedentary time is reduced in conjunction with meeting physical activity guidelines. This research provides valuable insights into the importance of lifestyle modifications, particularly in older populations, for enhancing metabolic health and reducing the risks of cardiovascular diseases and type 2 diabetes.
