The effects of increasing physical activity and reducing sedentary time in healthy, sedentary workers.

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Engaging in regular physical activity is essential for maintaining good health and well-being. Because employed adults spend the majority of their workday waking hours in the workplace, offering exercise programs at work may be an efficient strategy to increase physical activity; a recent meta-analysis has shown that some workplace physical activity interventions can improve both health and important worksite outcomes. The emergence of compelling evidence linking prolonged sitting to detrimental health outcomes, including mortality, has prompted calls for new thinking within public health messages to include both being physically active and reducing time spent sitting. However, the extent to which changes in metabolic/cardiovascular and productivity outcomes arising from a workplace physical activity program may be enhanced through a combined intervention approach (physical activity + sedentary behaviour reduction) has not been investigated. The proposed study will investigate the efficacy of a gymnasium-based exercise program with and without the combination of individually tailored feedback to reduce sedentary time on cardiovascular health outcomes and productivity in healthy, sedentary adults. A total of 68 full-time Baker IDI staff aged 20-65 years with a BMI less than 40 kg/m2 who are typically sedentary (sit at work equal to 4 hours/d and watch television equal to 2 hours/d), are not physically active (less than 150 minutes/wk moderate-to-vigorous physical activity), not on glucose, blood pressure or lipid lowering medications, not pregnant and otherwise healthy will be recruited to participate. The proposed study will involve a two-arm parallel group randomised trial conducted over 9 months which includes three phases. Phase 1: Baseline (1 week): Following initial screening for eligibility, behavioural, metabolic and physiological measurements will be performed to establish baseline values. Phase 2: Intervention Phase (3 months): Participants will then be randomly assigned to one of two groups: 1. Gymnasium-Based Exercise Only (n=34) 2. Gymnasium-Based Exercise + Sedentary Behaviour Reduction Intervention (n=34) At the completion of three months, all behavioural, metabolic and physiological measurements will be reassessed. Participants will undertake three, one hour exercise sessions (which combine aerobic and resistance training) per week for three months. All sessions will be developed and supervised by an exercise physiologist or qualified personal trainer and will be conducted at the Baker IDI Healthy Lifestyle Research Centre research gymnasium. Participants assigned to the Gymnasium-Based Exercise + Sedentary Behaviour Reduction Intervention will additionally receive guidance and support to reduce their sedentary time at work and increase their number of breaks in sedentary time (ie: changing from sitting to standing). Phase 3: Maintenance Phase (9 months): All participants will undergo a nine month maintenance phase whereby gymnasium-based exercise will be required on at least two and up to three days per week. At the completion of the maintenance phase, all behavioural, metabolic and physiological measurements will be reassessed.Study outcomes will include: metabolic (fasting blood glucose,insulin and lipids) and anthropometric measures, blood pressure, physical activity, sedentary time and breaks in sedentary time (primary); and work productivity, self perceived general and mental health and exercise compliance (secondary). Sedentary behaviour and physical activity time will be assessed in the study using accelerometers (Actigraph model GT3Xplus), worn during waking hours on selected days and positioned over the right hip via a belt. Accelerometers are similar in size and shape to pedometers and record data on physical activity duration, frequency and intensity. Breaks in sedentary time will be assessed using inclinometers (model activPAL)) worn discretely on the upper thigh area fixed with hypoallergenic, micropore tape. Inclinometers are equivalent in size to a matchbox and measure the number of postural changes from sedentary to upright (standing). An activity diary will be used in combination with the two devices to allow participants to record when they put on/took off the devices or engaged in non- ambulatory physical activities (ie. cycling, swimming) that are not able to be recorded by the accelerometer. Participants will also enter work start/finish times in the diary on those work days the devices are worn. It is anticipated findings from the proposed research study will be used to inform future interventions targeting behavioural change across the “whole of day” (during exercise and non exercise time) in at risk populations eg. overweight/obese, diabetics, individuals with metabolic syndrome.

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