Thesis Defence: The impact of a 12-week exercise snack intervention on inflammatory markers and immune function in people living with obesity
July 22 at 9:00 am - 1:00 pm
Ella Harness, supervised by Dr. Jonathan Little, will defend their thesis titled “The impact of a 12-week exercise snack intervention on inflammatory markers and immune function in people living with obesity” in partial fulfillment of the requirements for the degree of Master of Science in Health and Exercise Sciences.
An abstract for Ella Harness’ thesis is included below.
Defences are open to all members of the campus community as well as the general public. Registration is not required for in-person defences.
Abstract
Prevalence of obesity (excess adiposity which poses a risk to health) has more than doubled in the past 30 years, with physical inactivity and sedentary lifestyles being significant contributors to this increase. Obesity is associated with chronic inflammation, and although exercise provides anti-inflammatory effects through changes in immune cell phenotype and function, many people living with obesity do not meet physical activity guidelines. Exercise snacks involve short (≤1 minute) bouts of vigorous physical activity performed throughout the day and may represent an accessible way to increase physical activity and interrupt sedentary time. In lab-based studies, exercise snacks appear to improve cardiorespiratory fitness while early real-world interventions support feasibility and tolerability. However, the impact of exercise snacks on inflammatory markers and immune function remains unknown. In this thesis, 51 inactive adults living with obesity (47F, 4M; Age 50±7 yrs; BMI 35.3±4.3 kg/m2) were randomized to exercise snacks (n=26, 4 x 1-min vigorous bouts per day on ≥5 days per week) or a stretching/mobility exercise comparator group (n=25, on the same prescription), supported by a smartphone application. Pre- and post-intervention fasting blood samples were analysed for plasma cytokines, immune cell counts, monocyte phenotype, and lipopolysaccharide (LPS)-induced tumour necrosis factor (TNF)-α secretion from whole blood. There were no significant changes observed for plasma cytokines (p>0.21) or total white blood cell count (p=0.74). There was, however, a significant decrease in monocytes in both groups post-intervention (main effect of time, p<0.05). Although there were no differences in monocyte subset distribution (p>0.099), a significant decrease in surface expression of the key LPS sensing protein, TLR4, was observed on all monocyte subsets in both groups post-intervention (main effect of time, p<0.001). Despite these changes in TLR4, immune function assessed by LPS-induced TNF-α secretion was unaltered (p>0.214). Overall, these data suggest an effect of interrupting sedentary time with both vigorous exercise snacks and light-intensity mobility/stretching breaks on reducing monocyte counts and TLR4 expression in people living with obesity.
