With most U.S. adults sitting 9–12 hours daily and the risks of inactivity becoming more apparent, the popular press and the scientific community concur that “sitting is the new smoking.” Indeed, there is mounting evidence linking sedentary lifestyles to cardiovascular diseases and all causes of mortality (Diaz et al. 2017).
Though the threat seems clear, one major question has puzzled researchers: Can people reduce their risks by taking short breaks in otherwise long periods of sitting still?
Recent research offers some promising answers: This month I’m reviewing two studies suggesting that brief activity breaks after about 30 minutes of sitting can help to address the risks of sedentary lifestyles. I’m also including 10 novel movement ideas (five walking, five resistance) to get clients moving, based on the new research.
Study 1: The Value of Activity Breaks
Diaz, K.M., et al. 2017. Patterns of sedentary behavior and mortality in U.S. middle-aged and older adults. Annals of Internal Medicine, 167 (7), 465–75.
Purpose. Examining the association between objectively measured sedentary time and all causes of mortality.
Participants. Almost 8,000 black and white volunteers (aged 45 and older) in the REGARDS study, which examined racial and regional stroke disparities in the U.S.
Methods. Cardiovascular risk factor data and other demographics were collected by telephone interview and in-home physician examination at the start of the study. Participants were followed from 2009 to 2013 (a mean of 5.7 years). Volunteers wore hip-belt accelerometers at different intervals to assess their daily movement. Accelerometers are similar to pedometers and can measure energy expenditure quite accurately.
Results. On average, most adults in this study spent 12.3 hours (out of a 16-hour waking day) in a sedentary behavior, primarily sitting. Total sitting time was found to correlate highly with all causes of mortality. However, adults who interrupted sedentary time with movement (at least) every 30 minutes had the lowest mortality risk. The researchers urge amending physical activity and exercise guidelines to recommend that adults do some type of movement every 30 minutes of their waking hours to combat the harm of sustained sitting.
Study 2: Activity Quality and Quantity
Dempsey, P.C., et al. 2016. Benefits for type 2 diabetes of interrupting prolonged sitting with brief bouts of light walking or simple resistance activities. Diabetes Care, 39 (6), 964–72.
Purpose. Determining whether interrupting prolonged sitting with brief bouts of light-intensity walking or simple resistance activities improves cardiometabolic risk markers in adults with type 2 diabetes.
Participants. Twenty-four volunteers, all of them inactive, overweight/obese adults (14 men, 10 women; aged 62 ± 6 years; body mass index: 25–40 kg/m2; hemoglobin A1c levels of 6.5%–9%); all diagnosed with type 2 diabetes.
Methods. After initial telephone screening, the volunteers attended a medical screening that included a 12-lead resting EKG, a blood chemistry workup, resting blood pressure measurement, and a physical exam by a physician. Participants were familiarized with treadmill walking and taught simple resistance training exercises, including half squats, heel raises, gluteal contractions and knee raises.
The volunteers completed three 8-hour sessions, randomized and separated by 6–14 days. The longer separation was needed to sufficiently “wash out” the influence of insulin, the one variable that could have affected other key metabolic variables over the course of a few days. The sessions consisted of
- a control protocol: 8 hours of uninterrupted sitting
- variable 1: sitting plus 3 minutes of treadmill walking at 2 miles an hour every 30 minutes for 8 hours
- variable 2: sitting plus 3 minutes of resistance training every 30 minutes for 8 hours
The volunteers were asked not to do any type of exercise or to drink coffee or alcohol for 48 hours before the trial-session testing. To minimize diet-induced variability, their diets were standardized before each session.
Results. Both activity-break sessions significantly lowered blood glucose compared with the control session—a very positive finding because it shows that cells were using glucose for fuel. More good news: Insulin levels were significantly lower in the activity-break sessions than in the control session. Furthermore, the activity-break sessions showed significantly lower effects on C-peptide protein, a marker of insulin production. Interestingly, blood triglycerides were significantly lower in the resistance training activity-break session than in the control condition, but this was not true in the treadmill-walking session.
Dempsey et al. noted that the volunteers’ lifestyles represented a large part of the U.S. population—older adults who have or are at risk for type 2 diabetes—who do not adhere well to traditional exercise programs. The researchers propose that sedentary people and those with type 2 diabetes and similar health conditions may find it much easier to adhere to this helpful guidance during their waking hours: For every 30 minutes of sitting, get 3 minutes of activity (walking or simple resistance exercises or a combination of both).
Rapid innovations in communications, workplaces, transportation and entertainment seem certain to encourage prolonged sedentary behavior (Dempsey et al. 2016). The study by Dempsey and colleagues recommends that 3 minutes of walking or simple body-weight resistance exercise (at a light to moderate intensity) for every 30 minutes of sedentary time can significantly improve metabolic factors directly related to cardiovascular disease and type 2 diabetes.
Some clients may want to get creative with their intermittent 3-minute bouts of walking. Five walking styles introduced in this column (see the sidebar “Five Sample Walking Intervals”) are modified and derived from interval training research. Other clients may wish to break up their sedentary periods with resistance training moves. I have mixed up four movements (three from Dempsey et al., plus one more) into five patterns (see the sidebar “Five Simple Resistance Exercises”). Other clients may choose to just move around for 3 minutes.
Encourage clients to complete their activity breaks at a light to moderate intensity. Many interval training apps for mobile devices can help your clients time these movement periods.