Many adults spend a large part of their day sitting, especially at work. Long periods of sitting and not moving enough can increase the risk of health problems such as heart disease and type 2 diabetes. This risk is even higher in people who have early warning signs like being overweight, having high blood pressure, or problems with blood sugar. Together, these problems are called metabolic syndrome. The goal of this study is to find out whether combining regular exercise with reducing sitting time during the day can improve heart and metabolic health more than exercise alone. About 40 adults between 18 and 65 years old who work mainly at a desk and sit for more than 9 hours a day will take part. All participants will first continue their normal daily routine for two weeks. After that, they will be randomly placed into one of two groups for eight weeks: Exercise group: Participants will follow the World Health Organization guidelines for physical activity. This includes two sessions of moderate exercise each week (such as brisk walking or cycling) and one session of more intense exercise each week. Exercise plus less sitting group: Participants will do the same exercise program, but they will also be encouraged to sit less during the workday. They will be asked to stand more, use sit-stand desks if possible, and avoid sitting for longer than one hour at a time. Participants will visit the research center three times for health tests. These tests include blood samples to look at blood sugar, insulin, and fats in the blood, measurements of blood pressure and heart function, body composition scans, fitness tests, and questionnaires about sleep, diet, and quality of life. They will also wear activity monitors to measure how much they sit, stand, and move. The main outcome is how the body handles sugar (insulin sensitivity). The researchers hope to learn whether sitting less, in addition to exercising, leads to better improvements in heart and metabolic health. The results may help develop better lifestyle advice to prevent heart disease and diabetes in people with desk jobs.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
30
Individualised Physical Activity Plan (8 weeks): • Two weekly sessions of moderate-intensity physical activity (MIPA): Frequency: 2 sessions per week. Unsupervised. Duration: Initially 40 minutes per session, increasing to 50 minutes by week 4. Type of Activity: Participants can select from brisk walking, cycling, swimming, or elliptical training. Intensity: 40-60% of maximal oxygen consumption, monitored with wearable heart rate devices. • One weekly session of vigorous-intensity physical activity (VIPA): Frequency: 1 session per week. Supervised or predetermined. Duration: Initially 20 minutes per session, increasing to 30 minutes by week 4. Type of Activity: Options include running, high-intensity interval training (HIIT), or fast cycling. Intensity: 60-90% of maximal oxygen consumption, tracked with heart rate devices. • Weekly check-ins will allow adjustments based on individual feedback and progress.
Participants will be encouraged to replace seated work with standing work and engage in light physical activity breaks. • Workplace Integration Strategies: Participants working in an office setting will be provided with adjustable sit-stand desks where possible. • Active Breaks and Movement Interventions: Participants will be prompted to take short (2min) active breaks after prolonged periods of sedentary behaviour. Break activities will include standing, stretching, or light movement such as walking.
Univeristeit Hasselt
Diepenbeek, Limburg, Belgium
Homeostatic model assessment for insulin resistance (HOMA-IR)
The HOMA-IR is calculated from the fasting insulin and glucose concentration.
Time frame: From enrollment to the end of the intervention at 8 weeks.
Whole-body insulin sensitivity index (ISI)
An oral glucose tolerance test will be performed for assessment of whole body insulin sensitivity using the whole-body insulin sensitivity index (ISI). The ISI is calculated from both insulin and glucose concentrations.
Time frame: From enrollment to the end of the intervention at 8 weeks
Area under the curve of insulin concentrations
An oral glucose tolerance test will be performed for assessment of whole body insulin sensitivity by calculation of the area under the curve of insulin concentrations.
Time frame: From enrollment to the end of the intervention at 8 weeks
Insulinogenic index
An oral glucose tolerance test will be performed for assessment of beta cell function by calculation of the insulinogenic index. The insulinogenic index is calculated from both insulin and glucose concentrations.
Time frame: From enrollment to the end of the intervention at 8 weeks.
Body composition
Body composition is evaluated by Dual-energy X-ray absorptiometry. Fat mass (in kg), lean body mass (in kg), body fat percentage (in %) and visceral adipose tissue (in grams) will be derived from the Dual-energy X-ray absorptiometry.
Time frame: From enrollment to the end of the intervention at 8 weeks.
Cardiorespiratory Fitness
Cardiorespiratory fitness will be measured as peak oxygen consumption (V̇O2peak) using a graded cardiopulmonary exercise test (CPET) on a bike with pulmonary gas exchange analysis (Jaeger Oxycon®) until volitional exhaustion.
Time frame: From enrollment to the end of the intervention at 8 weeks.
Area under the curve of glucose concentrations
An oral glucose tolerance test will be performed for assessment of whole body insulin sensitivity by calculation of the area under the curve of glucose concentrations.
Time frame: From enrollment to the end of the intervention at 8 weeks
Steps per day
Physical activity will be quantified using the activPAL3™ activity monitor.
Time frame: From enrollment to the end of the intervention at 8 weeks. For one week during the first four weeks of the intervention. For one week during the last four weeks of the intervention.
Sitting time
Sedentary behaviour will be quantified using the activPAL3™ activity monitor.
Time frame: From enrollment to the end of the intervention at 8 weeks. For one week during the first four weeks of the intervention. For one week during the last four weeks of the intervention.
Moderate to vigorous physical activity
Physical activity will be quantified using the activPAL3™ activity monitor.
Time frame: From enrollment to the end of the intervention at 8 weeks. For one week during the first four weeks of the intervention. For one week during the last four weeks of the intervention.
Light intensity physical activity
Physical activity will be quantified using the activPAL3™ activity monitor.
Time frame: From enrollment to the end of the intervention at 8 weeks. For one week during the first four weeks of the intervention. For one week during the last four weeks of the intervention.
Sleep
Physical activity will be quantified using the activPAL3™ activity monitor.
Time frame: From enrollment to the end of the intervention at 8 weeks. For one week during the first four weeks of the intervention. For one week during the last four weeks of the intervention.
Body weight
Body weight (in underwear) is determined using a digital-balanced weighting scale to the nearest 0.1kg
Time frame: From enrollment to the end of the intervention at 8 weeks
Height
Body height is measured to the nearest 0.1cm using a wall-mounted Harpenden stadiometer, with participants barefoot
Time frame: From enrollment to the end of the intervention at 8 weeks.
Body mass index
Body mass index (BMI; kg/m²) is calculated from weight and height measurements (weight/height²).
Time frame: From enrollment to the end of the intervention at 8 weeks
Waist and hip circumference
Waist and hip circumferences will be measured to the nearest 0.1 cm using a flexible metric measuring tape with participants barefoot (in underwear) in standing position. Waist circumference is measured at the midpoint between the lower rib margin and the top of the iliac crest. Hip circumference is measured at the widest circumference of the hip at the level of the greater trochanter. Waist-to-hip ratio is calculated by dividing waist circumference (cm) by hip circumference (cm). Waist-to-height ratio is calculated by dividing waist circumference (cm) by height (cm).
Time frame: From enrollment to the end of the intervention at 8 weeks
Blood pressure
After an initial resting period of 10 min with participants in a supine position in a quiet room with constant temperature (21°C), systolic and diastolic blood pressure (BP; in mmHg) will be measured at least 3 times at 2-min intervals until BP is stable using an electronic sphygmomanometer (Omron®) from the left arm and documented as the mean value of the three final measurements.
Time frame: From enrollment to the end of the intervention at 8 weeks
Vascular endothelial function
Vascular function will be assessed by FMD according to published guidelines. These measurements take place at 9h and involve doppler ultrasound imaging of the superficial femoral artery. A cuff will be placed on the right lower leg, and the superficial femoral artery is imaged longitudinally. FMD will be measured at baseline and after a 5-min occlusion phase (reactive hyperaemia response). FMD will be quantified as the percentage difference between peak and baseline diameter (FMD%).
Time frame: From enrollment to the end of the intervention at 8 weeks
Cardiac autonomic function
Cardiac autonomic function will be operationalized as heart rate variability by means of continuous beat-to-beat heart rate signal measurements. time domain and frequency domain analysis of the R-R intervals will be performed
Time frame: From enrollment to the end of the intervention at 8 weeks
Concentration of glucose
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks
Concentration of insulin
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks.
Concentration of total cholesterol
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks.
Concentration of Low-Density Lipoprotein cholesterol
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks.
Concentration of High-Density Lipoprotein cholesterol
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks.
Concentration of triglycerides
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks.
Concentration of apolipoproteins
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks.
Concentration of CRP
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks.
Concentration of Interleukin 6 (IL-6)
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks.
Concentration of interleukin 1 (IL-1)
Blood analysis
Time frame: From enrollment to the end of the intervention at 8 weeks.
Sleep quality
Sleep quality over a period of one month will be assessed with the Pittsburgh sleep quality index (PSQI) which is a self-administered questionnaire consisting of 19 items that is reliable and valid to assess sleep problems.
Time frame: From enrollment to the end of the intervention at 8 weeks.
Food intake
Habitual dietary intake is assessed using a validated food frequency questionnaire (FFQ). In addition, participants will fill in a diary to evaluate dietary intake either with an app or on paper.
Time frame: From enrollment to the end of the intervention at 8 weeks
Quality of life (QOL)
Health-related quality of life (HRQOL) was measured using the Euroqol 5-D questionnaire (EQ-5D). The EQ-5D is a widely used and validated generic instrument consisting of five dimensions: mobility, self- care, usual activities, pain/discomfort and anxiety/depression.
Time frame: From enrollment to the end of the intervention at 8 weeks
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