Acute effects of breaking up prolonged sedentary time on cardiovascular disease risk markers in adults with paraplegia.

Elevated levels of cardiovascular disease (CVD) risk markers are highly prevalent in people with a spinal cord injury (SCI). Breaking up prolonged sedentary time with short, regular bouts of physical activity can reduce postprandial glucose and lipid levels in able-bodied individuals. The effects in people with paraplegia are unknown. The study aims were to examine the acute postprandial glucose (primary aim), lipid, blood pressure and psychological responses (secondary aims) to breaking up prolonged sedentary time in individuals with paraplegia. This was a randomised crossover design trial. Fourteen participants with paraplegia (age 51+/-9 years, trunk fat mass 44.3+/-7.7%) took part in the following two, 5.5 h conditions: (1) uninterrupted sedentary time (SED), and (2) sedentary time interrupted with 2 min of moderate-intensity arm crank ergometer physical activity every 20 min (SED-ACT). Standardised breakfast and lunch test meals were consumed during each condition. The outcomes were compared between conditions using linear mixed models. Glucose area under the curve (AUC) was significantly lower during the lunch postprandial period in SED-ACT versus SED (incremental AUC 1.9 [95% CI 1.0, 2.7) and 3.0 [2.1, 3.9] mmol/L2.5 h, respectively, p=0.015, f=0.34). There were no differences between conditions for the breakfast or total 5.5 h postprandial periods (p>0.05). Positive affect was higher in SED-ACT than SED (p=0.001). Breaking up prolonged sedentary time acutely attenuates lunch postprandial glucose and improves positive affect in people with paraplegia. This may have clinical relevance for reducing CVD risk and improving psychological wellbeing in this population.