There’s been good news about exercise in the last few years. Researchers have been reporting that we might not have to exercise as much as we think in order to derive benefits. Three years ago, for example, the U.S. Department of Health and Human Services published the second edition of “Physical Activity Guidelines for Americans,” which stated, “Adults should move more and sit less throughout the day. Some physical activity is better than none. Adults who sit less and do any amount of moderate-to-vigorous physical activity gain some health benefits.”
Now a new study from researchers in the Netherlands reports that just sitting less improves insulin sensitivity, a matter of considerable interest to people with diabetes. The report showed that a group of postmenopausal women who just stood up and walked more improved their insulin sensitivity nearly as much as others who did one hour of moderate to vigorous exercise.
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The research team, which was headed by Patrick Schrauwen, PhD, of the NUTRIM School of Nutrition and Translational Research at Maastricht University, recruited 12 women who were past menopause. Their ages ranged from 45 to 70, they were nonsmokers, had no active diseases, and their BMIs ranged from 25 to 35 (a BMI, or body-mass index, of 30 or above falls into the “obesity” category). The women had what the researchers described as a “physically inactive lifestyle” and their weight had been stable for the previous six months.
Each woman was assigned to do three activity regimens, each lasting four days — a sitting regimen, a sitting less regimen, and an exercise regimen. The sitting regimen involved sitting for 14 hours a day. The sitting less regimen required sitting for nine hours, standing for four hours, and walking for three hours a day. And the exercise regimen meant sitting for 13 hours and exercising for one hour a day (the exercise was done on a stationary bicycle). Food intake was kept as similar as possible in each regimen. Each subject was told to keep to their regular diet and to avoid alcohol and caffeine-rich drinks. Physical activity and body posture were measured with an activity monitor and the participants also kept a diary that recorded their physical activity.
The researchers measured the subjects’ insulin sensitivity by means of a hyperinsulinemic-euglycemic clamp, or insulin clamp. This device has been called the “gold standard” for measuring insulin sensitivity since it was invented at the University of Texas School of Medicine in 1979. In addition, the researchers performed muscle biopsies to identify changes at the molecular level.
Sitting less linked to improved insulin sensitivity
The researchers reported no significant difference in blood sugar levels among the three regimens. Compared to the sitting regimen, however, the subjects in the sitting less regimen saw a 13% improvement in peripheral insulin sensitivity, while those in the exercise regimen reported a 20% improvement. As for changes at the molecular level, exercise provided the greatest change but, the researchers said, “Though less pronounced than in the exercise regimen, sitting less induced similar metabolic changes at the end of the intervention.” The authors explained it this way: “Metabolomics analysis in muscle revealed overlap in the molecular profiles affected by exercise and sitting less, exemplified by a clear reduction of certain amino acids…which is a hallmark of vigorous exercise.”
The conclusions of the study, Dr. Schrauwen said, “confirm previous studies, but here we went a step further and also looked into the underlying mechanisms, with the questions if the mechanisms were similar between sitting less and exercise. Although this is not 100% the case, there was a good level of overlap between the two interventions.” And in an interview with the medical news website Healio, he added, “Not everyone, including patients with diabetes, [is] able to perform exercise on a routine basis. The implication of our study is that if you are not able to exercise, there are other alternatives that can also have beneficial health effects, such as the lighter activities that you may be able to incorporate in daily life.”