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Title: Behavioural and biological relationships between leisure-time physical activity and health outcomes during shift- and night-work
Author: Fullick, Sarah
ISNI:       0000 0004 2689 0187
Awarding Body: Liverpool John Moores University
Current Institution: Liverpool John Moores University
Date of Award: 2010
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Shift-work is increasingly common in society and is associated with a number of health inequalities. The health effects of shift-work can include a redudion in quality and quantity of sleep, insomnia, chronic fatigue, anxiety and depreSSion,decreased vigilance, metabolic syndrome, adverse cardiovascular (especially blood pressure), gastrOintestinal effects and reproductive effects in women. Shift-work is also associated with disturbances to a workers domestic and social life. Physical activity is known to either prevent or alleviate these health inequalities in those with 'normal diurnal' lifestyles such as day-workers. However, shift-work generally decreases opportunities for physical adivity. Moreover, the favourable affects of physical activity on such health inequalities have not been confirmed in shift-workers. The studies in the present thesis are designed to examine the associations between shift-work and physical activity covering a wide range of physiological and psycho-social variables in shift-workers. The first descriptive study was designed to provide the first detailed and multi-researchstrategy examination of LTPA and its correlates in shift-workers. One hundred and sixty one shift-workers partiCipated in the initial cross-sectional study. A cohort of ten of these partiCipants also volunteered for further diary- and inteNiew-based studies. PartiCipants completed the SSI together with a LTPA questionnaire. Gender, job type, age and shift-work experience were explored as correlates of LTPA. The cohort also completed a 7-day diary and wore an accelerometer for assessment of activity counts during work, leisure, and bedtime when working each shift-type (days, nights and rest). Participants also completed a semi-strudured email-administered interview. The total energy expenditure per week in LTPA of male shift-workers was found to be twice that of women. Midwives recorded the lowest LTPA. Firefighters reported the most LTPA. The time spent out of bed during night shift days was 4-h higher compared with rest days. Data from this study indicated that LTPA is generally low amongst shift-workers, the majority of whom are overweight or obese. Jobtype and gender are much more influential on LTPA than age or experience. Shift-workers spend more of their time on rest days in bed. The second descriptive study was designed to explore the relationships between coping strategies adopted by shift-workers and their leisure-time energy expenditure. The importance of coping strategies has been highlighted in previous research. Ninety-five participants completed an adapted version of the completed the SSI together with a LTPA qUestionnaire. Predictors of age, time spent in shift-work, gender, marital status and the various shift-work coping indices were explored with step-wise multiple regression. Leisuretime energy expenditure over a 14-day period was entered as the outcome variable. Gender (p < 0.023) and time spent in shift-work (p < 0.051) were found to be predictors of energy expenditure, with the most experienced, male shift-workers expending the most energy during leisure-time. Overall 'disengagement' coping scores from the SSI were positively related to leisure-time energy expenditure (p < 0.054). In males, disengagement of sleep problems (p > 0.086) was found to be negatively correlated to energy expenditure, whereas disengagement of domestic-related problems was found to be positively related to energy expenditure (p < 0.001). These relations were not found in female shift-workers (p > 0.762). These data indicated that experienced male shift-workers participate in the most leisure-time physical activity. These people 'disengage' more from their domestic-related problems, but less from their sleep-related problems. The next laboratory-based study was designed to examine the acute effects of evening exercise and meal frequency on psychophysiological and performance-related variables during a subsequent period of simulated night-work. Nine healthy participants, completed at least two crossover trials beginning at 18:00 h. Between 19:00-20:00 h, participants either rested or exercised at 50%V02peak and then remained awake throughout the night, completing various tasks until 05:15 h. Six participants completed a total of four trials in which they exercised or rested while either one standardized (SOkJlkg) meal at 22:00 h or two smaller (30 kJ/kg) meals at 22:00 and 02:00 h were eaten. Core Body Temperature (Tc), wrist activity, mood, sleepiness, arousal, self-chosen work-rate, and reaction time were all measured throughout the simulated night-shift. Following exercise, Tcwas Significantly lower throughout the night-shift compared with no prior exercise (95% Cl = 0.00 to 1.01°C), even though wrist activity was higher and sleepiness was lower after exercise. Self-chosen workrate was significantly higher (95% Cl = 20 to 43 W) and reaction time faster during the nightshift that followed exercise. Reaction time and alertness were worst when only 1 meal was ingested during the night-shift (p <0.04). These data indicate that a single bout of evening exercise can improve sleepiness as well as mental and physical performance during a subsequent simulated night-shift ... The findings from the studies in this thesis indicate that many of the short-term health benefits of exercise are apparent in contexts of shift- and night -work. The relatively small final intervention study demonstrates the potential utility of an individualised lifestyle intervention based on motivational interviewing for shift-workers.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: QP Physiology ; RC1200 Sports Medicine