20 Apr Type 2 Diabetes: “Stand Up, Sit Less, Move More, More Often” For Better Glucose Control
MedicalResearch.com Interview with:
MPhEd, PhD in Medicine (expected June 2016)
Physical Physical Activity and Behavioural Epidemiology Laboratory
Baker IDI Heart and Diabetes Institute
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: In addition to too little physical activity (PA), sedentary behavior – defined as any waking sitting or reclining behavior with low energy expenditure – has emerged as a ubiquitous and significant population-wide influence on cardiometabolic health outcomes, with potentially distinct and modifiable environmental and social determinants. There is now a consistent base of epidemiologic evidence reporting deleterious associations of excessive sedentary behaviors (e.g. TV viewing, car use, and desk work) with mortality and cardiometabolic morbidity, independent of moderate-vigorous PA.
To date, efforts to influence participation in moderate-to-vigorous exercise (i.e. 30 min a day of ‘exercise’ on most days a week for health) at the population level, such as through large-scale campaigns to promote walking, and other initiatives to encourage people to exercise during their leisure time have achieved only modest success. There may, however, be untapped preventive-health and clinical management potential through shifting the high volume of time spent sedentary to light-intensity physical activity interspersed throughout the day. As such, sedentary behavior represents a potentially feasible and therapeutic target, particularly in the promotion of metabolic health.
We posited that people with type 2 diabetes (T2D) were likely to derive the greatest benefits from interrupting their sitting time. However, until now the contributions of prolonged sitting and/or interrupting prolonged sitting with very-brief bouts of light-intensity PA had never been experimentally tested in patients with T2D. Moreover, this study for the first time moved beyond interrupting sitting with standing or ambulatory bouts (although walking bouts were also examined), which may have differing levels of metabolic stimulus (i.e. not physiologically taxing the body enough), practicality, or health efficacy, to examine a potential addition/alternative: simple resistance activities (SRA). A key premise behind these SRA bouts (half-squats, calf raises, gluteal contractions, and knee raises) were that they required no specialized equipment, only small amounts of space, and could be easily performed in a fixed position behind a work desk or at home with minimal disruption to work tasks or leisure pursuits. In addition, they also markedly increase muscle activity, and may also have other longer-term benefits (for example physical function, muscle strength, bone density), however we can only speculate on these aspects at present.
In this study in men and women with type 2 diabetes, plasma glucose, insulin and C-peptide (marker of insulin secretion and pancreatic beta cell function) levels following standardized breakfast and lunch meals were all markedly attenuated when prolonged sitting was regularly interrupted with light walking or resistance activities (3 min every 30 min) over an 8 hour day. Plasma triglyceride levels were also reduced for both types of activity bout; however, the reduction was only significant for the SRAs. Interestingly, the magnitude of glucose reduction for the walking bouts was greater in women for glucose levels.
MedicalResearch.com: What should clinicians and patients take away from your report?
Response: Although efficacy should be tested in larger and longer duration trials, in addition to the essential promotion of purposeful moderate-vigorous and leisure-time physical activity – which is important for metabolic control – it seems prudent (in the interest of doing no harm) that healthcare professionals seriously consider providing prescriptive advice to type 2 diabetes patients on reducing and regularly interrupting prolonged sitting time.
A simple message is to aim to minimize the amount of time spent in prolonged unbroken bouts of sitting, and look to break up these sitting periods as often as possible (Stand Up, Sit Less, Move More, More Often). Depending on the context of patients everyday lives, they might aim to try and find their own ‘sweet spot’ of both purposeful activity (exercise) and incidental movement/reduced sitting time throughout the day – as they both seem to come with their own sets of health outcomes that are likely to be complementary. Certainly, the combined effects of excessive sitting and being physically inactive seem to be very bad for our health. As such, we need to start thinking about our activity levels as more of a ‘whole of day’ approach. So, try to exercise, move more and sit less on a daily basis – here we emphasize that the latter two behaviors (sitting and incidental activity) are not taken as seriously as they should be, given our modern ‘sitting-centric’ environments.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: This study is a ‘proof of concept’ in the acute setting that simple interruptions in sitting time (with either light-walking or simple body weight resistance activities) are metabolically beneficial. In future interventions, it will be important to examine the chronic effects of these interventions (i.e. weeks, months). This should be assessed in larger samples in ecologically relevant, free-living, and workplace environments, using a broader range of participants (including premenopausal women and patients with less well-controlled type 2 diabetes [e.g., patients with poorly controlled diabetes on insulin or sulfonylurea dependent, with b-cell dysfunction and increased risk of experiencing hypoglycemia]). Moreover, it will be important to dig down deeper into the potential physiological mechanisms of the changes in glucose kinetics, as well as the interactions with other factors (e.g. exercise, dietary variations, sleep). Building on this evidence base in future studies will help inform the development of more specific public health guidelines for the management of type 2 diabetes.
MedicalResearch.com: Is there anything else you would like to add?
Response: Humans are designed to move. Our biological systems function optimally when we are regularly moving and physically active. The insidious prolonged periods of sitting that now characterize much of our day to day lives – especially our working lives – are missed opportunities for healthy movement. The bottom line is our bodies simply aren’t built for such a stationary existence – and there is growing evidence that this can have physiological consequences. Indeed, within modern society, many adults now spend the majority of their waking hours seated (up to 70%), a figure that far surpasses the hunting, gathering and migratory patterns of our ancestors. It’s important to remember that sitting is still okay (we need to rest); the problem is we are becoming addicted to our chairs – sit-aholics so to speak!
Paddy C. Dempsey, Robyn N. Larsen, Parneet Sethi, Julian W. Sacre, Nora E. Straznicky, Neale D. Cohen, Ester Cerin, Gavin W. Lambert, Neville Owen, Bronwyn A. Kingwell, and David W. Dunstan
Benefits for Type 2 Diabetes of Interrupting Prolonged Sitting With Brief Bouts of Light Walking or Simple Resistance Activities Diabetes Care published ahead of print April 13, 2016, doi:10.2337/dc15-2336