0
0
A study suggests that the most effective time to enhance the correlation between daily moderate to vigorous physical activity and obesity is between 7 a.m. and 9 a.m. This finding contrasts with conflicting epidemiological results regarding the optimal timing of exercise for weight management. The research was published in Obesity, the flagship journal of The Obesity Society.
Lead author Tongyu Ma, PhD, an assistant professor in the Health Sciences Department at Franklin Pierce University, Rindge, N.H., and the Department of Rehabilitation Sciences at The Hong Kong Polytechnic University, Hong Kong, China, commented on the study, saying, “Our study introduced a novel tool to investigate the diurnal pattern of physical activity and its impact on health outcomes.”
While previous studies have focused on the frequency, intensity, and duration of physical activity, few have delved into the diurnal pattern of accelerometer-measured physical activity to determine when people are most active. It remains uncertain whether cumulative physical activity at different times of day similarly influences obesity.
Furthermore, it’s unclear whether meeting the recommended physical activity guidelines (150 minutes per week of moderate to vigorous activity) in various patterns equally benefits obesity reduction. The current study sought to explore whether the diurnal pattern of accelerometer-measured activity alters the association between such movement and obesity.
Researchers analyzed data from the 2003–2004 and 2005–2006 cycles of the National Health and Nutrition Examination Survey by the Centers for Disease Control and Prevention, as accelerometry was in use during that period. A total of 5,285 participants were cross-sectionally examined.
The diurnal pattern of objectively measured moderate to vigorous physical activity was classified into three categories using K-means clustering analysis: morning, mid-day, and evening. K-means is a well-established algorithm used to identify underlying patterns in unlabeled data sets.
The results revealed a strong linear connection between moderate to vigorous physical activity and obesity in the morning group, whereas a weaker, curvilinear link was found in the midday and evening groups. Participants who adhered to the physical activity guidelines in the morning cluster had lower body mass indices and waist circumferences compared to those in the other clusters. Self-reported dietary recall indicated that participants in the morning cluster had healthier diets and consumed less energy per unit of body weight compared to other clusters.
The study also found that participants in the morning cluster spent significantly more time in sedentary behavior than those in the other clusters. Despite this, the lower body mass index and waist circumference outcomes in the morning group remained consistent.
Overall, participants in the morning cluster were 10 to 13 years older than those in the other groups. This cluster also had the highest percentage of female participants among the three groups. Most participants in the morning group were predominantly non-Hispanic White, had a college education or higher, and had never used tobacco or alcohol.
Ma and colleagues concluded, “Our findings suggest that the diurnal pattern of moderate to vigorous physical activity could be another important aspect to consider when understanding the complexity of human movement.”
Rebecca Krukowski, PhD, a clinical psychologist specializing in behavioral weight management, commented on the study, saying, “This is exciting new research that aligns with a common tip for achieving exercise goals – scheduling exercise in the morning before emails, phone calls, or meetings that might distract you.”
However, Krukowski cautioned that since this is a cross-sectional study, it’s unknown whether people who consistently exercise in the morning may differ systematically from those who exercise at other times in ways not measured in this study. For instance, individuals who regularly exercise in the morning might have more predictable schedules, potentially being less likely to be shift workers or have caregiving responsibilities that hinder morning exercise. Predictable schedules could have additional beneficial effects on weight that weren’t assessed in this study, such as related to sleep duration/quality and stress levels. Additionally, the “morning larks” who consistently rise early for exercise may be biologically distinct from their “night owl” counterparts.
