Paddy C. Dempsey

Interrupting prolonged sitting with brief bouts of light walking or simple resistance activities reduces resting blood pressure and plasma noradrenaline in type 2 diabetes

Objective: Prolonged sitting is increasingly recognized as a ubiquitous cardiometabolic risk factor, possibly distinct from lack of physical exercise. We examined whether interrupting prolonged sitting with brief bouts of light-intensity activity reduced blood pressure (BP) and plasma noradrenaline in type 2 diabetes (T2D). Methods: In a randomized crossover trial, 24 inactive overweight/obese adults with T2D (14 men; mean ± SD; 62 ± 6 years) consumed standardized meals during 3 × 8 h conditions: uninterrupted sitting (SIT); sitting + half-hourly bouts of walking (3.2 km/h for 3-min) (light-intensity walking); and sitting + half-hourly bouts of simple resistance activities for 3 min (SRAs), each separated by 6–14 days washout. Resting seated BP was measured hourly (mean of three recordings, ≥20-min postactivity). Plasma noradrenaline was measured at 30-min intervals for the first hour after meals and hourly thereafter. Results: Compared with SIT, mean resting SBP and DBP were significantly reduced (P < 0.001) for both light-intensity walking (mean ± SEM; −14 ± 1/−8 ± 1 mmHg) and SRA (−16 ± 1/−10 ± 1 mmHg), with a more pronounced effect for SRA (P < 0.05 versus light-intensity walking). Similarly, mean plasma noradrenaline was significantly reduced for both light-intensity walking (−0.3 ± 0.1 nmol/l) and SRA (−0.6 ± 0.1 nmol/l) versus SIT, with SRA lower than light-intensity walking (P < 0.05). Mean resting heart rate was lowered by light-intensity walking (−3 ± 1 bpm; P < 0.05), but not SRA (−1 ± 1 bpm). Conclusion: Interrupting prolonged sitting with brief bouts of light-intensity walking or SRA reduces resting BP and plasma noradrenaline in adults with T2D, with SRA being more effective. Given the ubiquity of sedentary behaviors and poor adherence to structured exercise, this approach may have important implications for BP management in patients with T2D.

Sedentary behavior as a risk factor for cognitive decline? A focus on the influence of glycemic control in brain health

Cognitive decline leading to dementia represents a global health burden. In the absence of targeted pharmacotherapy, lifestyle approaches remain the best option for slowing the onset of dementia. However, older adults spend very little time doing moderate to vigorous exercise and spend a majority of time in sedentary behavior. Sedentary behavior has been linked to poor glycemic control and increased risk of all‐cause mortality. Here, we explore a potential link between sedentary behavior and brain health. We highlight the role of glycemic control in maintaining brain function and suggest that reducing and replacing sedentary behavior with intermittent light‐intensity physical activity may protect against cognitive decline by reducing glycemic variability. Given that older adults find it difficult to achieve current exercise recommendations, this may be an additional practical strategy. However, more research is needed to understand the impact of poor glycemic control on brain function and whether practical interventions aimed at reducing and replacing sedentary behavior with intermittent light intensity physical activity can help slow cognitive decline.

Does the type of activity “break” from prolonged sitting differentially impact on postprandial blood glucose reductions? An exploratory analysis

Frequent breaks in prolonged sitting are associated beneficially with glycaemic control. However, the contribution of energy expenditure to this relationship has not been well characterised. In this exploratory analysis, data from 3 laboratory trials that standardised test meals, cohort characteristics (overweight/obese, sedentary), and break frequency and duration were pooled. Higher energy expenditures of different types of breaks (standing, light- or moderate-intensity walking) were associated with lower postprandial glucose and insulin responses in a dose-dependent manner.

Prolonged Uninterrupted Sitting Elevates Postprandial Hyperglycaemia Proportional to Degree of Insulin Resistance

Prolonged uninterrupted sitting is related adversely to cardiometabolic risk markers and postprandial hyperglycaemia, relative to sitting interrupted by regular brief activity breaks. However, whether the magnitude of hyperglycaemic responses to prolonged sitting is dependent upon the underlying degree of insulin resistance remains unclear. Data were pooled from 3 randomized cross‐over laboratory‐based trials (n = 62) that examined the postprandial blood glucose‐ and insulin‐lowering effects of prolonged sitting vs sitting interrupted by regular brief activity breaks in overweight/obese adults who had normal or impaired glucose metabolism (2 trials) or type 2 diabetes not treated by insulin (1 trial). Corrected for study effects, the magnitude of differences in postprandial glucose and insulin responses between the 2 conditions was significantly exacerbated with poorer baseline levels of fasting glucose, insulin and/or surrogate markers of β‐cell function and insulin resistance. This suggests that those with higher underlying levels of insulin resistance may derive greater metabolic benefits from regularly interrupting prolonged sitting than their healthier counterparts. If these findings can be replicated, they may have implications for future targeting and optimization of physical activity/sedentary behaviour interventions in the prevention and management of type 2 diabetes.

Prompts to increase physical activity at points-of-choice between stairs and escalators: what about escalator climbers?

Since 1980, many studies have evaluated whether stair-use prompts increased physical activity by quantifying changes in stair use. To more completely evaluate changes in physical activity, this study addressed the often-overlooked assessment of climbing up escalators by evaluating the degree to which stair-use sign prompts increased active ascent-defined as stair use or escalator climbing. Over 5 months, at an airport stairs/escalator point of choice, we video-recorded passersby (N = 13,544) who ascended either stairs or escalators, on 10 days with signs and 10 days without signs. Ascenders using the stairs, standing on the escalator, and climbing the escalator were compared on days with versus without signs using multivariable logistic regression. The percentage of ascenders on days with versus without signs were as follows: stair use, 6.9 versus 3.6 percent; escalator standing, 75.2 versus 76.0 percent; and escalator climbing, 18.5 versus 20.4 percent. Signs more than doubled the odds of stair use (vs. escalator use; OR = 2.25; 95% CI = 1.90-2.68; p < .001). Signs decreased the odds of escalator climbing (vs. escalator standing or stair use); OR = 0.90; 95% CI = 0.82-0.99; p = .028). Signs increased the odds of active ascent versus escalator standing by 15 percent (OR = 1.15; 95% CI = 1.05-1.25; p = .002). Although stair-use prompts increased stair use more than twofold (125%), they increased active ascent by only 15 percent, partly because escalator climbing-a behavior not targeted by the intervention-decreased. Although our results corroborated the established consensus that point-of-choice prompts increase stair use, future studies should test interventions designed to increase active ascent.

Prolonged uninterrupted sitting increases fatigue in type 2 diabetes

Fatigue is a prevalent, costly and disabling clinical complaint among those with type 2 diabetes. In a randomized crossover trial, prolonged uninterrupted sitting increased fatigue by 29% relative to days when sitting was regularly interrupted by brief activity-breaks. This may have implications for diabetes-related quality of life, occupational productivity and self-care.