But what about the movement in between what would count toward your daily physical activity target (like jogging, brisk walking, or a HIIT workout) and sitting on your couch? The research has been less conclusive when it comes to determining how the daily activities that keep us on our feet and off the couch (like cooking, washing dishes, or puttering around the house) affect our health and mortality risk. Now a study designed to measure the health benefits of just that — low-intensity activity — found that indeed any level of movement decreases risk of premature death. RELATED: Here’s How Much Exercise You Need The research, published in August 2019 in the BMJ, combined data from eight other studies from the United States and Europe for which more than 36,000 individuals’ movements were tracked via motion sensors, which measured the amount and the intensity of physical activity. The studies followed those individuals for six more years to track deaths among the individuals. It is the first study of its kind and size to show the role that light physical activity can play in reducing the risk of death, says Ulf Ekelund, PhD, a professor in the department of sports medicine at the Norwegian School of Sports Sciences in Oslo and the lead author of the study. “We found that all physical activity counts, regardless of intensity,” Dr. Ekelund says. “For those who cannot participate in moderate intensity activities, such as brisk walking, there are beneficial effects of lower-intensity activity.” RELATED: How to Start Exercising and Stick With It
Across the Board, Data Finds Benefits to Moving More
Ekelund and his team identified eight existing observational prospective studies that had assessed sitting and activity time by accelerometry (which measures both intensity and duration of movement) and tracked all-cause mortality with a median follow-up time of 5.8 years. The participants in each study included in the new analysis wore a tracker for at least 10 hours a day for four or more days. RELATED: How to Pick the Best Fitness Tracker for You A unique aspect of this study is that the researchers asked for and were granted access to the raw data from each study, and then reanalyzed the entire data set of 36,383 participants who were at least 40 years old (the average age was 62) — which allowed them to look at trends in a large sample of people. The researchers grouped everyone in the study into one of four quartiles, ranging from the least active to the most active, for six different categories of activity (light activity, low-light activity, high-light activity, moderate to vigorous activity, vigorous activity, and sedentary behavior), controlling for age, gender, body mass index (BMI), socioeconomic status, smoking status, and education level. Activity level intensity was measured in “counts per minute” (with “counts” referring to movement). So the higher the count per minute, the more intense the activity was. Tasks like washing dishes, cooking, or slow walking would have counted as light activity; brisk walking, vacuuming, or mowing the lawn would fall into the moderate-intensity category; and vigorous activity would be along the lines of jogging, digging, or carrying a heavy load. The data consistently showed that more physical activity, no matter what the intensity, reduced the risk of death in the following ways:
Individuals who spent the most time engaged in any physical activity (those in the top quartile group when it came to duration of activity) were 73 percent less likely to die during the study than those who spent the least amount of time being active (those in the lowest quartile when it came to exercise duration), no matter what the intensity of their physical activity.People in the second highest quartile for total physical activity were 52 percent less likely to die during the study period than people in the lowest quartile.People who logged the most light-intensity physical activity were 62 percent less likely to die than the most sedentary group.Sedentary time above 9.5 hours per day was associated with an increased risk of death. Those who spent 10 hours sedentary had a 50 percent higher risk, and those who spent 12 hours sedentary had almost three times the risk when compared with the least sedentary quartile.The actual number of deaths was about 4.5 to 5.5 times higher in the least active compared with the most active quarter and about 2.5 times higher in the most sedentary quarter compared with the least sedentary quarter.
When looking at only moderate activity among all the study participants, the risk of dying early continued to decrease for the more moderate activity a person did until it plateaued at 25 minutes per day (more moderate activity per day beyond that wasn’t harmful, but it didn’t yield additional benefit in terms of extending life). The same trend was true when looking at light activity alone. More light activity was associated with lower mortality risk until it leveled off at about five hours per day (again, light activity beyond that amount wasn’t harmful, but didn’t provide additional benefit). Researchers also found a reduced risk of death in participants who performed the most moderate to vigorous physical activity, although the number of participants who engaged in this level of activity was relatively low, which made exact mortality estimates less reliable, according to the authors. A limitation of the data is that if participants were sicker at the onset of the study when the activity level was measured, their condition may have caused them to move less, which could have skewed the results. In an effort to minimize that potential effect, the researchers excluded people who died within the first two years of follow-up and reanalyzed the data. The results and the associated levels of risk didn’t change when compared with the data set that included those individuals.
In All Cases, Even Small Amounts of Moving Is Better Than Nothing
This research strongly affirms that even small amounts of activity can have benefits for a sedentary person in terms of their overall health, says Stephen Kopecky, MD, a cardiologist at the Mayo Clinic in Rochester, Minnesota, who was not involved in the research. “We don’t need to go to the gym for an hour,” says Dr. Kopecky. RELATED: Two Large Studies Find Americans Continue to Move Less, Sit More Using objective data from the activity trackers strengthened the associations between physical activity, regardless of intensity, and the risk of death compared with other studies that have relied on self-reported data alone, says Ekelund. “The magnitude of associations was almost twice as strong as those previously observed in other studies where physical activity was assessed by self-reported activity levels,” he says. Kopecky adds that one limitation of this data is a potential bias in the samples. “Randomized studies only include subjects who are interested and give informed consent. In exercise studies, this means generally only motivated subjects enroll,” says Kopecky. And in observational studies, there may be additional bias in the outcomes because subjects know they are being observed, he says.
Light, Moderate, and Intense: Different Kinds of Activity May Benefit Health in Different Ways
A significant contribution of this study is to show with objective evidence (from the activity tracker data) that low-intensity exercise is associated with benefits, says William Kraus, MD, the director of clinical translation at the Duke Molecular Physiology Institute, who was not involved in the research. For many years researchers relied on self-report to assess physical activity levels, and those methods are not a very accurate way to measure low-intensity physical activity, says Dr. Kraus. “It is only with the advent of objective measures of physical activity — like accelerometers and step counters — that we have been able to quantify less intense and shorter bouts of physical activity,” he says. This research also helps show the benefit of all types of movement throughout the day, Kraus says. Although higher intensity exercises can improve cardiovascular fitness, less-intense physical activity may be better at improving glucose control and reducing the risk of diabetes, he says. RELATED: Strength Training Found to Lower Heart Disease and Diabetes Risk, Whether or Not You Do Cardio “We believe this might be related to the energy sources used for these different intensity activities,” says Kraus. Less-intense activities burn fats in preference to glucose, and the opposite is true for more vigorous exercise, says Kraus. That may account for the varying health effects of different intensity activities, he adds. The most important takeaway here is that being sedentary is bad for your health, says Kraus. “This research suggests that any physical activity can counter that,” he says. Less sitting and more movement is the ticket, even if the bout of exercise is short or light intensity, says Kraus.
