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Cardiovascular mechanisms of the occupational physical activity health paradox: 24-hour physical activity, blood pressure, and heart rate in active workers

Quinn, Tyler (2020) Cardiovascular mechanisms of the occupational physical activity health paradox: 24-hour physical activity, blood pressure, and heart rate in active workers. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Recent evidence suggests an occupational physical activity (OPA) health paradox where OPA is associated with adverse cardiovascular health. Physiological mechanisms to explain this paradox have not been studied.
METHODS: Nineteen male workers (68% White/Caucasian, age=46.6 years, BMI=27.9 kg/m2) with high reported OPA completed a submaximal exercise test and wore ambulatory activity (ActiGraph and activPAL) and cardiovascular (blood pressure (BP) and heart rate (HR)) monitors for 7days, including at least one workday and non-workday. Individuals recorded work stress levels, work-time, nonwork-time, and sleep times in a diary. Physical activity profiles were described and compared to aerobic physical activity and OPA recommendations. 24-hour cardiovascular load (HR, systolic and diastolic BP) and nocturnal HRV were compared on workdays vs. non-workdays using adjusted linear mixed models. Effect modification by fitness level was explored using interaction models. The effect of work-related stress was analyzed by comparing workdays with low and high stress to non-workdays.
RESULTS: Participants were significantly less sedentary and more active on workdays vs. non-workdays (all p<0.05). While most participants met aerobic activity guidelines, OPA exceeded recommended intensity level and upright time limits. 24-hour HR and diastolic BP were significantly higher on workdays vs. non-workdays (β=5.4 beats/min, p<0.001 and β=2.7 mmHg, p=0.019, respectively) but systolic BP did not differ (β=2.0 mmHg, p=0.317). Nocturnal HRV (low and high frequency power) was significantly lower on workdays vs. non-workdays (β=-0.27, p=0.025 and β=-0.33, p=0.014, respectively); other parameters (RMSSD, SDNN, LF/HF) were similar. Workday vs. non-workday cardiovascular load was not modified by fitness level (p-for-interactions>0.703). When stratified by stress level and compared to non-workdays, 24-hour HR was elevated on both low- (β=4.7 beats/min, p<0.002) and high-stress workdays (β=5.4 beats/min, p<0.001), 24-hour diastolic BP was only elevated on high-stress workdays (β=4.4 mmHg, p=0.023), and 24-hour systolic BP was never elevated (p>0.05).
CONCLUSIONS: Activity was higher and exceeded OPA recommendations on workdays versus non-workdays. Workdays were also associated with elevated 24-hour cardiovascular load and reduced HRV. Fitness did not modify this relationship, but high job stress seemed to exaggerate it. These results suggest high 24-hour cardiovascular load and job stress as potential mechanisms contributing to the OPA health paradox.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Quinn, Tylertdq1@pitt.edutdq10000-0002-0172-062X
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairBarone Gibbs, Bethanybbarone@pitt.eduBBARONE0000-0002-0732-6148
Committee MemberChristopher, Klinecek51@pitt.eduCEK510000-0003-1025-9430
Committee MemberNagle, Elizabethnagle@pitt.eduNAGLE
Committee MemberRadonovich, Lewismto5@cdc.gov0000-0001-7583-1413
Date: 17 May 2020
Date Type: Publication
Defense Date: 10 April 2020
Approval Date: 17 May 2020
Submission Date: 20 April 2020
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 112
Institution: University of Pittsburgh
Schools and Programs: School of Education > Health and Physical Activity
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Ambulatory Blood Pressure Heart Rate Variability Leisure Time Physical Activity Occupational Physical Activity Paradox
Date Deposited: 17 May 2020 17:34
Last Modified: 17 May 2020 17:34


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