Abstract
Recent studies suggest that substituting sitting with light physical activity has beneficial metabolic effects, but it is unclear if this is associated with parallel changes in endothelial function. Data from three randomized cross-over studies were analyzed, in which 61 subjects (with normal weight, overweight and type 2 diabetes) followed different activity regimens (Sit, SitLess and/or Exercise) of four days each. Subjects were instructed to sit 14 h/day (‘Sit’), to substitute 1 h/day of sitting with moderate-to-vigorous cycling (‘Exercise’) or to substitute 5–6 h/day sitting with light-intensity walking and standing (‘SitLess’). Physical activity was assessed 24 h/day by accelerometry (ActivPAL) and diet was standardized. Fasted circulating biomarkers of endothelial dysfunction, lipids and insulin sensitivity were assessed the morning after each activity regimen. The endothelial dysfunction score (ED-score) was computed by averaging the Z-scores of the circulating biomarkers of endothelial dysfunction. Compared to Sit, Exercise resulted in lower ED-score, sICAM1 and sE-selectin (p < 0.05), while no significant changes were observed after SitLess. The ED-score, sVCAM1 and sE-selectin were lower after Exercise compared to SitLess (p < 0.05). In contrast, compared to Sit, insulin sensitivity (HOMA2-IR) and plasma lipids (HDL-cholesterol, non-HDL-cholesterol, total cholesterol and Apo B) did not change significantly after Exercise but were improved after SitLess (p < 0.05). In conclusion, light physical activity and moderate-to-vigorous physical activity had a differential effect on risk markers of cardio-metabolic health and suggest the need of both performing structured exercise as well as reducing sitting time on a daily basis.
Highlights
Cardiovascular disease is one of the leading causes of morbidity and mortality in modern societies[1]
The median duration of type 2 diabetes in this study was 6 years (4–10) and diabetes was well-controlled with a mean (SD) HbA1c (Hemoglobin A1c) of 6.7% (0.8)
On a short-term basis (4 days), intermittent increases in shear stress during moderate-to-vigorous physical activity (MVPA) seem to be more important for endothelial function than the improvement in insulin sensitivity as observed after light physical activity (LPA)
Summary
Cardiovascular disease is one of the leading causes of morbidity and mortality in modern societies[1]. This is still debated[6,7], several studies suggest that this rise in sedentary behavior might be associated with increased risk of cardiovascular disease, independent of time spent in MVPA3,8,9 In line with these observational studies, we recently observed that reducing sitting time and substituting it with light physical activity (LPA) improved insulin sensitivity and plasma lipids but not after MVPA, when estimated energy expenditure was held constant[10,11]. In recent years we performed three separate intervention studies, which had a nearly identical protocol, in which we investigated the metabolic effects of substituting sitting with LPA and MVPA in sedentary subjects with normal weight, overweight and type 2 diabetes (T2D) In this manuscript, we determined the effects of these interventions on biomarkers of endothelial dysfunction. As two of these studies had an intervention arm with structured MVPA, we were able to compare the effects of MVPA versus LPA on these variables
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