Frequently Interrupting Prolonged Sitting With Light Body-Weighted Resistance Activity Alters Psychobiological Responses to Acute Psychological Stress: A Randomized Crossover Trial

• Published in: Annals of behavioral medicine Vol. 57; no. 4; pp. 301 - 312
• Main Authors: Chauntry, Aiden J, Bishop, Nicolette C, Hamer, Mark, Paine, Nicola J
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 12.04.2023
• Subjects: Blood Glucose; Cardiovascular Diseases - complications; Cross-Over Studies; Humans; Hydrocortisone; Insulin; Interleukin-6; Male; Obesity; Walking; Prolonged sitting; Response to stress; Sedentary behavior; Interrupting sitting; Acute psychological stress; Stress reactivity
• ISSN: 0883-6612; 1532-4796
• DOI: 10.1093/abm/kaac055

Abstract Background Uninterrupted prolonged sitting and exaggerated psychobiological reactivity to acute psychological stress are associated with increased risk of cardiovascular disease (CVD). Breaking up prolonged sitting with frequent, short bouts of light-intensity physical activity acutely lowers CVD risk markers under resting conditions. Purpose To examine whether frequent interruptions to prolonged sitting with body-weighted resistance activity can acutely lower systolic blood pressure (SBP; primary outcome) and other cardiovascular (CV), inflammatory, and cortisol (secondary outcomes) responses to acute psychological stress. Methods This randomized crossover trial included 17 sedentary participants (9 men; mean ± SD age; 24.0 ± 0.5 years) who completed two conditions: (i) interrupting 4 hr of sitting with 4 min of light body-weighted resistance activity every 30-min (BREAK), and (ii) 4 hr of uninterrupted sitting (SIT). Following the BREAK and SIT intervention windows, CV, inflammatory, and cortisol markers were measured at rest, during stress tasks (8-min Paced Auditory Serial Addition Test [PASAT] and 3-min cold pressor [CP]), and 45-min recovery periods. Results There were main effects of time for CV parameters (SBP, diastolic blood pressure, heart rate, cardiac output, and total peripheral resistance [all p < .001]), inflammatory markers (interleukin-6 [IL-6]), and cortisol (p < .05) in response to stress. Time-by-condition interaction effects revealed that in the BREAK-condition there was lower SBP during immediate recovery from the CP (mean {95% confidence interval [CI]}: 127.2 [121.3, 133.4] vs 133.4 [125.5, 141.7] mmHg; p = .020), higher concentrations of plasma IL-6 45-min post-PASAT (2.70 [1.97, 3.70] vs 1.71 [1.32, 2.22] pg/mL; p = .010), and larger (nonsignificant) salivary cortisol concentrations 8-min post-CP (6.29 [4.60, 8.58] vs 3.97 [3.16, 4.99] nmol/L; p = .079). Conclusions Interrupting prolonged sitting with frequent bouts of light intensity body-weighted resistance activity alters psychobiological responses to acute psychological stress. Further research should explore the longer-term implications for CVD risk. Interrupting prolonged sitting with frequent but short and low-intensity bouts of activity may positively enhance blood pressure responses to short episodes of psychological stress. Lay Summary Sitting for long periods without interruption and the way in which we physically respond to short-term psychological stress are linked to heart disease risk. Breaking up sitting with short, frequent bouts of light activity can lower heart disease risk but how this may improve how we respond to stress is unknown. Our study investigated if interruptions to prolonged sitting with body-weighted resistance activity lowered changes seen under stress such as changes in blood pressure (BP) and inflammation. Seventeen participants undertook two testing sessions. One session interrupted 4 hr of sitting with 4-min of light activity every 30-min, and the other session was 4 hr of uninterrupted sitting. After each session, participants did two stress tasks: one math-based task and one where feet were submerged in cold water. The changes in BP and inflammation to stress were measured. We found when breaking-up sitting time with activity, BP was lower after the cold-water task compared to when people did not break up their sitting. In summary, breaking up sitting with frequent bouts of light activity may influence how we respond to short-term stress, but future research needs to explore what these short-term changes mean for the longer-term risks of heart disease.