A Comparison of Acute High- and Moderate-Intensity Exercise on Cardio- Metabolic Function and Sleep Among Shift Workers

Purpose: To assess the acute effect of moderate and high-intensity exercise on markers of cardio-metabolic function among rotational shift workers. Methods: Sedentary men (n = 26, age: 38 ± 8 years; BMI: 32.2 ± 6.0 kg/m², VO_2peak 32.6 ± 6.7 mL/kg/min) employed in rotational shift work were recruited and underwent objectively assessed sleep quality (~ 7 days actigraphy) prior to reporting for laboratory testing. Baseline venous blood was collected to analyse fasted glucose, insulin and inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1 receptor antagonist (IL-1Ra). Participants were randomly allocated a 30 min cycling intervention of either high intensity interval training (HIIT): 1:4 ratio of 60 s at 100% and 240 s at 50% VO_2peak, or moderate intensity continuous training (MICT); continuous cycling at 60% VO_2peak. Fasted venous blood was collected post intervention (0, 30, 60 min) before subsequent night’s sleep was assessed via actigraphy. Results: HIIT (P < 0.016) and MICT (P < 0.016) significantly increased IL-1Ra immediately and 30 min post exercise. Significantly decreased wake after sleep onset (WASO) were observed following MICT (P < 0.05). No significant changes were observed for supplementary sleep variables, insulin sensitivity, IL-6 or TNF-α for either intervention group (P > 0.05). Conclusion: High- and moderate-intensity exercise acutely increase anti-inflammatory markers post exercise and MICT significantly reduces sleep fragmentation in rotational shift workers. Results which are associated with improved cardio-metabolic function and indicate the potential validity of exercise as an intervention to offset the hypothesised adverse health effects of rotational shift work.