Breaking sitting with light activities vs structured exercise: a randomised crossover study demonstrating benefits for glycaemic control and insulin sensitivity in type 2 diabetes

Abstract

Aims/hypothesis We aimed to examine the effects of breaking sitting with standing and light-intensity walking vs an energy-matched bout of structured exercise on 24 h glucose levels and insulin resistance in patients with type 2 diabetes. Methods In a randomised crossover study, 19 patients with type 2 diabetes (13 men/6 women, 63 ± 9 years old) who were not using insulin each followed three regimens under free-living conditions, each lasting 4 days: (1) Sitting: 4415 steps/day with 14 h sitting/day; (2) Exercise: 4823 steps/day with 1.1 h/day of sitting replaced by moderate-to vigorous-intensity cycling (at an intensity of 5.9 metabolic equivalents [METs]); and (3) Sit Less: 17,502 steps/day with 4.7 h/day of sitting replaced by standing and light-intensity walking (an additional 2.5 h and 2.2 h, respectively, compared with the hours spent doing these activities in the Sitting regimen). Blocked randomisation was performed using a block size of six regimen orders using sealed, non-translucent envelopes. Individuals who assessed the outcomes were blinded to group assignment. Meals were standardised during each intervention. Physical activity and glucose levels were assessed for 24 h/day by accelerometry (activPAL) and a glucose monitor (iPro2), respectively. The incremental AUC (iAUC) for 24 h glucose (primary outcome) and insulin resistance (HOMA2-IR) were assessed on days 4 and 5, respectively. Results The iAUC for 24 h glucose (mean ± SEM) was significantly lower during the Sit Less intervention than in Sitting (1263 ± 189 min × mmol/l vs 1974 ± 324 min × mmol/l; p = 0.002), and was similar between Sit Less and Exercise (Exercise: 1383 ± 194 min × mmol/l; p = 0.499). Exercise failed to improve HOMA2-IR compared with Sitting (2.06 ± 0.28 vs 2.16 ± 0.26; p = 0.177). In contrast, Sit Less (1.89 ± 0.26) significantly reduced HOMA2-IR compared with Exercise (p = 0.015) as well as Sitting (p = 0.001). Conclusions/interpretation Breaking sitting with standing and light-intensity walking effectively improved 24 h glucose levels and improved insulin sensitivity in individuals with type 2 diabetes to a greater extent than structured exercise. Thus, our results suggest that breaking sitting with standing and light-intensity walking may be an alternative to structured exercise to promote glycaemic control in patients type 2 diabetes.

Adding exercise or subtracting sitting time for glycaemic control: where do we stand?

“…As acknowledged by Duvivier and colleagues [8], the increased step count accomplished in the Sit Less condition (17,502 steps/day vs~4500 steps/day on the Sitting condition) would generally be considered an 'extreme' prescription for most people of this age and/ or with pre-existing disease. Similarly, the intensity and duration of the Exercise condition (5.9 METs for 65 min/day) is well above current exercise recommendations.…”

“…In this issue of Diabetologia Duvivier and colleagues [8] report the results of an interesting experimental study in 19 physically inactive, overweight/obese adults with type 2 diabetes. Using a randomised crossover design, the authors compared the effects of three 4 day activity regimens: (1) 'Sitting': 4415 steps/day with sitting 14 h/day; (2) 'Exercise': 4823 steps/day with 1.1 h/day of sitting replaced with three consecutive 20 min bouts of moderate-to-vigorous cycling, performed at least 2 h after breakfast; and (3) 'Sit Less': 17,502 steps/day with 4.7 h/day of sitting replaced with intermittent standing (2.5 h) and light-intensity walking (2.2 h) across the day.…”

“…The study by Duvivier and colleagues [8] is an important addition to the rapidly expanding evidence base on the glycaemic consequences of excessive sitting [7,[12][13][14][15]. However, only one previous experimental study has examined the effects of breaking up prolonged sitting with brief, intermittent bouts of light-intensity activities in a sample of type 2 diabetes patients, albeit under controlled experimental conditions [16].…”

“…However, only one previous experimental study has examined the effects of breaking up prolonged sitting with brief, intermittent bouts of light-intensity activities in a sample of type 2 diabetes patients, albeit under controlled experimental conditions [16]. Several aspects of the study by Duvivier and colleagues [8] From a clinical perspective, the findings of this study have several potential implications for acute glycaemic control in adults with type 2 diabetes: (1) that morning bouts of structured exercise may not fully compensate for the negative glycaemic effects of prolonged sitting over the rest of the day, (2) that the duration of non-sitting activities may be more important than intensity for glycaemic control, or (3) that the higher frequency of interrupting sitting time (every 30 min) compared with structured exercise, as well as its timing around meals, may have contributed to the more beneficial glycaemic effects.…”

“…Activity dose, timing and patterning In the context of high levels of sitting across the population, identifying the doses, timing and patterning of physical activity that are required to optimise cardiometabolic health is of great clinical and practical relevance to type 2 diabetes management. In the present study [8], structured Exercise was completed 2 h after the breakfast meal, which may have afforded the Sit Less condition an unfair advantage. In other words, had the structured exercise bout been placed 30-60 min after breakfast, just prior to the breakfast meal, or in the evening, then the differences between the Sit Less and Exercise conditions for 24 h glucose control or fasting insulin/lipid measures may have been different.…”