The Couch Will Not Make You Faster

Sit or Get Fit?

Reprint From Tufts University

New research makes the choice clearer than ever:  Physical activity is key to living healthier longer, while inactivity shortens your life.

If you need a push to get off the couch, a flurry of new research should provide plenty of motivation.  The findings about the negative effects of inactivity and the benefits of physical activity couldn’t be more stark: Sitting too much is dangerous for your health, while getting fit helps protect everything from your waistline to your brain.

“Any activity is better than nothing. That’s the really important message,” says Miriam E. Nelson, PhD, director of Tufts’ John Hancock Research Center on Physical Activity, Nutrition and Obesity Prevention. “Don’t think, I’ll never get there.” It’s important to take a stepwise approach.”

Screen time

Two new studies, published almost simultaneously, point to the health risks of sitting too much. In one, published in the Journal of the American College of Cardiology, Emmanuel Stamatakis, PhD, of University College London, and colleagues analyzed data on 4,512 respondents to the 2003 Scottish Health Survey, ages 35 and up. Over an average follow-up of a little more than four years, participants suffered 215 cardiovascular events (such as a heart attack or stroke) and 325 died from all causes.

People who spent at least two hours a day sitting in front of the computer or TV for entertainment were more than twice as likely to suffer a cardiovascular event than those with less than two hours of average daily screen time. Those heavy “recreational sitters” were also 52% more likely to die. Strikingly, even participants who exercised when not “recreationally sitting” did not mitigate the extra risk associated with too much sedentary screen time.

An analysis of a subset of participants who provided blood samples found that elevated levels of C-reactive protein (a marker for inflammation), greater body mass index (BMI) and low HDL (“good”) cholesterol partly explained why the sedentary were at greater risk. Researchers also suggested that excessive sitting might decrease healthy nitric oxide in blood vessels, due to reduced blood flow.

While the study wasn’t designed to prove cause and effect, Stamatakis and colleagues did conclude, “Our results support the inclusion of a sedentary behavior guideline in public health recommendations for cardiovascular disease prevention.”

Are you sitting down?

The second study, rather than relying on self-reported data, actually used accelerometers on participants’ hips to record active versus sedentary time-both at work and at play. Participants wore the accelerometers for an average of 14.6 hours a day, of which 8.44 hours were completely sedentary and only about 20 minutes were spent exercising. Among 4,757 adults, average age 46.5, longer sedentary time was associated with less-healthy measures of HDL cholesterol, insulin, insulin resistance, fasting triglycerides and C-reactive protein, as well as greater waist circumference. Genevieve Healy, PhD, MPH, of the University of Queensland in Australia, and colleagues published their results in the European Heart Journal.

What can you do if your job, say, demands, extended sitting time? Researchers found that periodically getting up and moving around for as little as a minute was linked to improvements in C-reactive protein scores and waist circumference.

Healy and colleagues concluded, “While further evidence of a causal nature is required from longitudinal and intervention studies, less sitting time would be unlikely to do harm, and would, at the very least, contribute to increase overall levels of energy expenditure.”

Shrinking “middle-age spread”

On the flip side, the benefits of staying physically active include the expected, such as staying slimmer, as well as such less obvious positives as reducing diabetes risk, improving arthritis symptoms and maintaining brain volume.

Start with the dreaded “middle-age spread.” Arlene L. Hankinson, MD, MS, of Northwestern University, and colleagues looked at the relationship between maintaining higher activity levels and changes in body mass index (BMI) and waist circumference over 20 years in young adults. Participants, initially ages 18 to 30, were quizzed about physical-activity levels at the study’s start and at periodic follow-ups. They were asked about participation in 13 moderate-and vigorous-intensity activities during the previous year, including sports, exercise, home maintenance and occupational activities.

Over those 20 years, men who maintained the highest activity levels gained an average of almost six pounds less than the least-active group and added 1.2 inches less to their waistlines. The difference was more pronounced for women, with the most-active group putting on 13.4 fewer pounds and staying 1.5 inches slimmer around the waist. Little difference was seen for either gender between the middle and least-active groups. Participants who kept up the recommended 150 minutes of moderate activity per week gained significantly less weight over 20 years than those who did not.

“These results suggest that maintaining higher activity levels during young adulthood may lessen weight gain as young adults transition to middle age,” the researchers concluded in the Journal of the American Medical Association (JAMA). “Our results reinforce the role of physical activity in minimizing weight gain and highlight the value of incorporating and maintaining at least 30 minutes of activity into daily life throughout young adulthood.”

10,000 steps against diabetes

Stepping it up not only helps you keep trimmer but also improves insulin sensitivity, a key indicator of diabetes risk, according to a new Australian study. Terry Dwyer, AO,MD,MPH, of the Murdoch Children’s Research Center, and colleagues put pedometers on 592 non-diabetic adult volunteers for two days, then repeated the test five years later. Although nearly two-thirds became more sedentary over that span, those who increased their steps counts whittled down their BMI and waist-to-hip ratio while boosting insulin sensitivity.

Researchers calculated that relatively sedentary individuals who added activity to reach 10,000 steps (about five miles) per day could knock almost a point off their BMI and improve insulin sensitivity by about 12%. The insulin-sensitivity benefit, although independent of calorie consumption, appeared to be largely due to lower body fat. Previous studies, the scientists noted in BMJ, had found positive effects of exercise interventions for diabetes prevention, but these new results suggest that “real-world” lifestyle changes can also pay off.

Rx for OA

Even a little extra physical activity can improve function and mobility among older adults with osteoarthritis of the knee. That’s the encouraging takeaway from a new Northwestern University study of 2,589 participants in the Osteoarthritis Initiative, average age 62.4. Dorothy D. Dunlop, PhD, and colleagues assessed levels of physical activity, at baseline and after one and two years, using the 26-question Physical Activity Scale for the Elderly (PASE), which ranges from sports activity to gardening to housework.

Both initially and at two years, greater physical activity was correlated to faster walking speed. Among the least-active adults with arthritis, 51% couldn’t walk fast enough (4 feet per second, 2.7 mph) to cross a street with timed traffic lights. But as activity levels went up so did walking speed. The findings demonstrate a “strong relationship” between physical activity and function, researchers concluded in Arthritis & Rheumatism, adding that “there was evidence of potential benefit of greater physical activity regardless of the level achieved.”

This is your brain on exercise

Your brain also benefits when your body is active. The latest study to demonstrate such a connection links aerobic exercise to volume in the hippocampus, a part of the brain that’s key to memory. Arthur Kramer, PhD, of the University of Illinois, and colleagues randomly assigned half of a group of 120 men and women in their mid-60s to a program of aerobic walking three times a week. The other half enrolled in stretching classes and served as a control group. Participants were tested for fitness and memory ability and given MRI scans to measure hippocampal volume. The hippocampus normally shrinks 1% to 2% a year with advancing age, contributing to memory loss and dementia risk.

After a year, however, participants in the aerobic-walking group had actually gained an average 2% in hippocampal volume. Those in the control group lost an average 1.4%. Improvements in fitness, measured by treadmill testing, were significantly associated with greater hippocampal volume. Those changes didn’t directly translate into a correlation between fitness and memory across study participants. But for the individuals in the walking group, increases in hippocampal volume were related to improvements in memory. In Proceedings of the National Academy of Sciences, Kramer and colleagues wrote that the results “clearly indicate that aerobic exercise is neuro-protective and that starting an exercise regimen later in life is not futile for either enhancing cognition or augmenting brain volume.”

If you were still clinging to an excuse for staying on the couch–“It’s probably too late in life to matter for me,” for example-we’re pretty sure  that just popped it. Time to lace up those sneakers and join the folks who are living healthier longer.