New Year’s resolution: Reallocate 30 minutes a day to health yourself

Ah, the holidays. What a wonderful time sitting around with extended family and friends, sharing memories, future ambitions, jokes, and, of course, plenty of food and drink.

And boy do we sit around and indulge. Who can resist my mother-in-law’s homemade coffee cake, cookies, and other assorted goodies? And the holiday dinner was wonderful with more flavorful dishes than I can remember. Each year seems better than the last!

Now comfortably back to my normal routine, I realize how differently I spend 24 hours each day during the holidays than I do during my normal routine.

How do you spend your day?

Scientists who study the ways in which people spend each 24-hour day have come to interesting and instructive conclusions about biomarkers related to disease risk and eventual health outcomes.

For most people, the 24-hour day is disproportionately distributed between sleep, sedentary behaviors (sitting, reclining, watching television, driving, etc.), and active behaviors that divide into two categories:

• Light-intensity physical activity can be defined as leisurely walking or doing household chores
• Moderate-to-vigorous physical activity is defined by a high-energy expenditure, such as brisk walking, jogging, running, swimming, cycling, or playing organized sports. Hard physical labor falls into this category as well.

Cross-sectional research suggests that optimal distribution of sleep, sedentary behaviors, and active behaviors correlates with biomarkers of risk for cardiovascular disease.

For example, optimal sleep duration (7-8 hours per day) and increased time spent in light- and moderate- to-vigorous physical activity associate with decreased markers of risk for cardiovascular disease.

Conversely, increased sedentary behaviors and long (>8 hours) or short (<7 hours) sleep duration associate with increased biomarkers of risk for cardiovascular disease.

Since each day is finite, increasing time in one behavior inevitably requires decreasing time in another. The health impacts of sleep, sedentary behaviors, and active behaviors depend not only on the behaviors themselves, but also on the behaviors they displace.

None of the literature reporting on sleep, sedentary behavior, or physical activity has accounted for the fixed-time nature in which these behaviors occur, or how their varying distributions may affect risk for cardiovascular disease.

But a recent study using data from the National Health and Nutrition Examination Survey from 2005–06 illuminates for the first time how allocation of these behaviors associates with biomarkers of risk for cardiovascular disease. Specifically this study examined whether decreased sedentary time or increased active behaviors were protective or synergistic in the relationship between biomarkers for disease and varying levels of sleep duration.

Reallocate time, decrease risk for cardiovascular disease

Researchers examined the activity and sleep patterns of nearly 2,200 individuals. They measured each individual’s risk for cardiovascular disease — including blood lipids, triglycerides, cholesterol, high- and low-density lipoproteins, insulin levels, blood pressure, waist circumference, and β-cell function as a marker of insulin sensitivity

The study investigated the effects of reallocating 30 minutes per day of sedentary time with equal time of either sleep or moderate-to-vigorous physical activity to determine impacts on risk for cardiovascular disease.

The results were very telling.

• Reallocating 30 minutes per day of sedentary time with equal time of light-intensity physical activity decreases triglycerides by 1.9 percent, lowers insulin by 2.4 percent, and decreases β-cell function by 2.2 percent.
• Reallocating 30 minutes per day of sedentary time with equal time of moderate-to-vigorous physical activity decreases waist girth by 2.5 percent, increases high-density lipoprotein cholesterol (the good lipid) by 4.4 percent, lowers triglycerides by 8.5 percent, lowers glucose by 1.7 percent, lowers insulin by 11.9 percent, and results in a 9.7 percent higher homeostasis model assessment of insulin sensitivity (β-cell function).
• Reallocating 30 minutes per day of sedentary time to increased sleep had beneficial associations with insulin (2.3 percent lower), 2 percent increase in β-cell function, and a minor effect on LDL cholesterol.

Make active living your new year’s resolution

Most research indicates people are unlikely to allocate more time to moderate-to-vigorous physical activity on a sustained basis. More success is reported when people reallocate some portion of their sedentary time to light-intensity physical activity.

It’s all about tradeoffs in how we spend our day, and these tradeoffs are likely to impact our health.

Minute-for-minute, moderate-to-vigorous physical activity is the most health-enhancing behavior, showing the most robust effect on the biomarkers of risk for cardiovascular disease.

I’m not recommending anyone exercise the entire day. But I am suggesting we reconsider how we spend our time. I’m confident you can find a way to replace some sedentary activities (e.g., television viewing) with additional physical activities (e.g., household chores, leisurely walks). Also, replacing sedentary time with quality sleep can provide additional benefits.

References 

• Buman, M.P., et al. “Reallocating time to sleep, sedentary behaviors, or active behaviors: Associations with cardiovascular disease risk biomarkers, NHANES,” 2005-06. American Journal of Epidemiology, 2013; 179(3):323.
• Buman, M.P., King, A.C. “Exercise as a treatment to enhance sleep.” American Journal of Lifestyle Medicine, 2010;4(6):500.
• Healy, G.N., et al. “Breaks in sedentary time — Beneficial associations with metabolic risk.” Diabetes Care, 2008;31(4):661.
• Healy, G.N., et al. “Sedentary time and cardio-metabolic biomarkers in U.S. adults: NHANES,” 2003–06. European Heart Journal, 2011;32(5):590.
• Matthews, C.E., et al. “Amount of time spent in sedentary behaviors in the United States,” 2003–04. American Journal of Epidemiology, 2008;167(7):875.
• Owen, N., et al. “Sedentary behavior: Emerging evidence for a new health risk,” Mayo Clin Proceedings, 2010;85(12):1138.