Increasing physical activity in office workers – the Inphact Treadmill study; a study protocol for a 13-month randomized controlled trial of treadmill workstations

The study will take place in Umeå, Northern Sweden. Umeå is located at latitude N 63° and has major seasonal variations, with cold winters and relatively warm summers. Forty of the participants (20 from each group) will start the study in April 2014 and 40 participants (20 from each group) will start the study in October 2014. Potential seasonal variations in outcome variables can thus be estimated.

Management personnel at the different office workplaces will first be contacted with information about the study and a presentation on the risks of sedentary behaviour. If granted by management, the research team will visit the companies to give an informational presentation about the study to the employees. At this visit, the employees will be thoroughly informed about the study and about the commitment expected of those participating. Those employees who can not attend this information session, but who shows interest in participating in the study, will receive the same information via telephone.

Employees from private companies as well as those from state, county, and municipal offices will be included in the study group. The settings in the different companies range from private offices to open office settings.

Participants aged between 40–67 years, with a body mass index (BMI) between 25–40 kg/m², and having an office job consisting of mainly sedentary tasks are eligible. Exclusion criteria includes diabetes mellitus, exhaustion disorder, moderate or severe depression or anxiety, severe kidney disease, severe cardiovascular disease, severe gastrointestinal or lung disease, untreated thyroid disease, pregnancy, a previous cardiovascular event such as transient ischemic attack/stroke, more than 6 % weight loss during the previous 6 months, engagement in extensive aerobic exercise training, or musculoskeletal pain making it difficult to walk on a treadmill. Participants are also excluded if they have more than one day of travel per work week or have plans to leave the organization during the study period.

For the functional magnetic resonance imaging (fMRI) measurements, exclusion criteria includes implanted metal or electrical devices, extraneous metal pieces in the body, metal splinters, claustrophobia, neurological diseases, or tattoos containing lead.

Employees interested in participating in the study will initially be screened for the inclusion and exclusion criteria via a telephone interview performed by a member of the research team. Those employees who are eligible and willing to participate in the study will then be called to the University hospital in Umeå to provide signed consent and to go through a more thorough screening process. At this visit, a clinical examination will be performed by a doctor at the clinical research centre, and routine blood samples will be taken for haemoglobin and plasma glucose/HbA1c levels and kidney and liver function. An experienced nurse will measure pulse rate, blood pressure, weight, and height.

At the screening visit, the participants will also complete questionnaires including the Hospital Anxiety and Depression scale (HAD scale), self-rated Exhaustion Disorder (s-ED), and the Workforce Sitting Questionnaire (WSQ) with regards to the exclusion criteria. The HAD scale is a commonly used clinically questionnaire and has been found to be valid for assessing symptom severity and caseness of depression and anxiety [21]. Based on clinical expertise, moderate-to-severe depression is suspected when scoring more than 10 points on the depression part of the scale, and moderate to severe anxiety is suspected when scoring more than 10 points on the anxiety part of the scale. The s-ED scale (the Institute for Stress Medicine, Gothenburg) is a four-item scale that follows a predefined scoring protocol. This questionnaire has good construct and predictive validity [22]. In the WSQ, as described by Chau et al. [23], the participants estimate how much time they spent sitting in different domains during workdays and non-workdays during the past 7 days. This questionnaire has acceptable reliability and validity [23].

The participants in both groups will receive an individual health consultation in the beginning of the study, which will be led by an experienced nurse. This consultation will be individually adapted and the participants will receive feedback on some of the measurements taken at screening and at baseline. The feedback includes weight circumference, BMI, blood pressure, and cholesterol and HbA1c-levels. Also included is feedback about their amount of sedentary time, which was subjectively estimated based on the WSQ at screening. This will be followed by information and discussion about physical activity and diet according to the guidelines used in the Västerbotten County Council (VLL). The participants’ own reflections and thoughts about their baseline values and their current life situation will then be discussed with the nurse. The health consultation will take about 30–40 min.

Written information folders about healthy lifestyles will be distributed to the participants. The information folder about physical activity emphasises the need for at least 30 min of moderate physical activity per day. To improve aerobic capacity and strength, the folder recommends exercise at a vigorous level 20–60 min two to three times per week. A few examples of how the participants can improve their everyday LPA to increase NEAT are also given in this folder, e.g. to take the stairs instead of the elevator, to walk or take a bike to and from work, to stand up while talking on the phone, or to try “walk and talk-meetings”.

Dietary recommendations will be provided in separate folders. An information folder is directed towards recommendations about diet for subjects with high blood lipid levels. An additional dietary health guide gives further recommendations about diet, especially for saturated, unsaturated and polyunsaturated fat, cholesterol, and trans fats, with suggested recipes. The information also includes other lifestyle factors, such as alcohol and smoking.

Participants in the intervention group will receive, apart from the health consultation, a treadmill workstation consisting of a treadmill adapted for desk use, which they will use for 13 months. This equipment will be installed in place of the subject’s regular working desk with a height-adjustable table. A physiotherapist will perform the instalment of the treadmill workstations and give ergonomic advice. Participants will be instructed on how to use the treadmill at a self-chosen speed and to gradually increase their time using the treadmill, starting with 15 min twice daily during the first week. After the initialization process, they will be instructed to use the treadmill for at least one hour per day, but preferably longer. Whenever they want to sit down during the day, the treadmill can be tipped sideways so that the desk can be lowered to chair level.

Participants in the intervention group receive booster e-mails from the research group at 4 time points (after 5–6 weeks, 19–20 weeks, 31 weeks, and 50 weeks) during the study period. In these booster e-mails, subjects receive information about the negative health effects of sitting, are inspired to use the treadmill as much as they can, and are reinforced to meet the criteria of at least one-hour of walking time per day. Participants in the control group will not receive any booster emails during the study period.

At baseline, demographic data including age, gender, marital status, educational attainment, and number of children will be asked for. Any new health problems, added medications and/or altered doses of already existing medications during the past 3 months will also be recorded at baseline and at 2, 6, 10, and 13 months. At the follow-ups, participants will also be asked to report any life events that may have occurred during the last 3 months that might possibly affect their health or wellbeing.

At baseline and at the 2-, 6-, 10-, and 13-month follow up visits, self-rated health will be obtained by two questions from the Swedish version of the RAND-36 (Lotti Orwelius et al., unpublished observations); “In general, would you say your health is…” and “Compared to one year ago, how would you rate your health in general now?”.

Daily light, moderate, and vigorous physical activity will be measured objectively with the tri-axial Actigraph wGT3x-BT activity monitor (ActiGraph, Pensacola, Florida, USA) at baseline and at the 2-, 6-, 10-, and 13-month follow-up visits. This monitor will be worn around the waist above the right hip with an elastic belt. Participants are asked to use the Actigraph during all their waking hours, except during water-based activities, for 14 consecutive days during each assessment period. The raw data will be collected at 30Hz.

Sitting/lying (reported as sitting), standing, and walking time, number of sedentary bouts, number of breaks from a sedentary bout, and total number of steps and cadence will be measured objectively with the activPAL3 and activPAL3 micro activity monitor (PAL Technologies Limited, Glasgow, UK; default settings) at baseline and at the 2-, 6-, 10-, and 13-month follow-up visits. The participants will wear one of these devices fastened to the anterior mid-line of the right thigh using Mepore surgical dressing. activPAL has been proven to provide valid, reliable, and sensitive measurements on changes in body postures and motion [24‐27], and in estimating breaks from sedentary time [27]. Participants will be asked to use the activPAL for 24 h, except during water-based activities, for the first seven days of each assessment period when they are simultaneously wearing the Actigraph.

During each measurement period, participants will report the time that they usually go to sleep and wake up on workdays and non-workdays, as well as the usual time that they arrive at and leave work. This will be used to calculate the variables from the activity devices during the entire day on both work and non-work days, as well as dividing the activity into working hours and non-working hours during work days. Participants will also be asked to report any period of not wearing the monitors.

Self-reported physical exercise will be recorded at baseline and at the 2-, 6-, 10-, and 13-month follow-up visits with the question, “how many days during the past 3 months have you exercised in workout clothes, with the purpose of improving your fitness and/or to feel good?” They will also be asked to report if, and if so how, they have made any changes in their daily activity habits during work, leisure time, and/or transportation during the past 3 months.

Participants will be asked to register their dietary intake using a food diary at baseline and at the 2-, 6-, 10-, and 13-month follow-up visits. This will be done on four of the days while they are wearing the Actigraph; three weekdays and one day during the weekend. The participants will be instructed by an experienced dietician to register their entire energy intake, specifying the type and amount of food and drink that they consume during these four days, estimated using a portion guide.

Anthropometric measurements will be taken at baseline and at the 6- and 13-month follow-up visits. This will be done at the clinical research centre at the University hospital in Umeå, Sweden, using standardized measurements. During these measurements, the participants will wear light indoor clothing without shoes.

Body height will be measured to the nearest 0.1 cm using a wireless stadiometer (Seca 264; Seca ltd, Hamburg, Germany). Body weight will be measured to the nearest 0.1 kg using a calibrated electronic digital scale (Tanita BWB-800 MA; Umedico AB, Rosersberg, Sweden). BMI is calculated as body weight in kilograms divided by body height in meters squared (kg/m²).

Waist and hip circumference will be measured with a tape measure to the nearest 0.5 cm. Waist circumference will be measured midway between the lower rib margin and the iliac crest during a light exhale. Hip circumference will be measured over the widest parts of the hips.

Sagittal abdominal diameter will be measured (Oscar Instrument AB, Hyssna M, art.nr. 7–506, Kungälv, Sweden) at the umbilical level, with the participants lying on their backs with extended legs.

Blood pressure will be measured twice at each follow-up visit on the right arm with the participant in a seated position. Pulse will be measured manually at the right wrist twice. The mean value of the blood pressure and pulse measurements will be reported.

Body composition will be measured with Dual X-ray absorptiometry (DXA) (Lunar Prodigy X-ray Tube Housing Assembly, Brand BX-1 L, Model 8743; GE Medical Systems, Madison, WI, USA) by an experienced nurse at baseline and at the 6- and 13-month follow-up visits at the clinical research centre. Absolute values of fat mass and lean mass, as well as android and gynoid fat mass, will be measured for each participant.

Basal blood samples will be drawn after an overnight fast by an experienced nurse at baseline and at the 6- and 13-month follow-up visits at the clinical research centre. Participants will be instructed to avoid high-intensity exercise and stressful situations on the day before the tests, and to avoid nicotine and caffeine on the morning before the test. Plasma cholesterol, triglycerides, HDL, and LDL and total cholesterol, HbA1c-level, high sensitivity C-reactive protein, and liver enzymes will be measured in the blood samples.

Musculoskeletal pain from the head, neck, shoulders, thoracic spine, lumbar back, hips, knees, and feet during the past 3 months will be measured at baseline and at the 2-, 6-, 10-, and 13-month follow-up visits using the Chronic Pain Grade Questionnaire (CPGS) [28]. Participants will complete the questionnaire at home. The CPGS has been shown to be a valid questionnaire [28, 29], and includes subscales for both pain severity and pain-related disability. The subscale scores are combined into a grade, classifying the participants into 5 categories ranging between 0 (no pain problem) to 4 (severe interference). An additional question was recently added to the questionnaire, which asks for the number of days of pain during the past 6 months. Pain is also classified as non-persistent (1–89 pain days) or persistent (90–180 pain-days) [30].

Saliva samples for cortisol measurements and stress scales will be performed at baseline and at the 6- and 13-month follow-up visits.

Saliva samples will be taken at 7 am, 11 am, 4 pm, and 11 pm during one workday. The participants are instructed to avoid high-intensity exercise on the day before as well as during the test day. They are also instructed not to eat, use nicotine, or brush their teeth one hour before the test. Premenopausal women are instructed to take the samples on the seventh day after the start of their menstruation. The participants will take the samples at home using Salivette® tubes. They are instructed to chew on the included swab for one minute or to keep the swab under their tongue for one and a half minutes. The swab is then put back into the tube and the lid is put on for storage. They will be instructed to keep the saliva samples in the refrigerator for up to one day before handing them over to the research team. The saliva samples will be analysed at the department of Clinical Chemistry, Umeå University hospital.

Self-reported stress during the past week will be measured using the Stress- and Energy scale (SE scale) [31]. The participants will complete the questionnaire at home. This scale consists of 12 adjectives of which 6 cover the dimensions of stress and 6 cover the dimension of energy. Answers are given on a 6-point scale (0–5) ranging from “not at all” to “extremely”.

The participants’ feelings of depression and anxiety during the past week will be measured at baseline and at the 6- and 13-month follow-up visits using the HAD scale [21]. The participants will fill out the questionnaire at home.

A cognitive test battery covering functions including episodic memory, working memory, and executive functions will be administered at 0, 6, and 13 months. The tests will be performed at Umeå University during office hours. The total time for the cognitive tests will be approximately 45 min. The selected tests are a mixture of computerized tests and pen and paper tests. Below are descriptions of each test and the order of the tests.

Twenty subjects from each study group will be randomly selected for fMRI scanning at baseline and at the 13-month follow-up. This will be performed at the Centre for Functional Brain Imaging at the University hospital in Umeå, Sweden. The participants will be instructed to eat as usual before the measurement, but to refrain from nicotine and caffeine one hour before the test and from high-intensity exercise and alcohol for twenty-four hours before the test.

High-resolution T1 images will be acquired in order to examine potential effects on grey matter volume. Furthermore, blood oxygen level dependent (BOLD) T2* images will be acquired during a 10 min rest period in order to evaluate functional resting state networks, a measure of global brain function across various ages [38]. The last task during scanning will be the Eriksen flanker task to evaluate task-specific effects on functional brain response. In the Eriksen flanker task, participants will indicate the direction of the middle arrow in either congruent (>>>>>) or incongruent (> > <>>) stimuli by pressing MRI-adapted buttons as fast and as accurately as possible. Accuracy and response time will be used as dependent measures.

At short-term follow-up visits, studies testing the effects of treadmill workstations have found that participants are generally positive and enthusiastic about the treadmill and would use it if available [13, 39]. A recent study investigated facilitators and barriers regarding usability, safety, comfort, and productivity in five female office workers who used treadmill workstations for 6 months [40]. By conducting an interview study after the study period is over, i.e. after 13 months, we will investigate the participants’ experiences with and attitudes towards working on a treadmill workstation, and further assess barriers and facilitators. The interview results may help with the development and implementation of active workstations and in the construction of activity-enhancing workplaces in the future.

This qualitative interview study includes individual semi-structured interviews. Approximately 15 interviews are estimated to be needed. Participants from the intervention group, who started in April 2014, will firstly be asked to participate. If more interviews are needed after this, participants from the intervention group starting in October 2014 will also be invited to participate. The interviews will be performed either at the companies where the participant works or at the university, depending on what works best for the participant. The study will be conducted using grounded theory methodology with an emergent design. The data will be processed through open, axial and selective coding, with constant comparison of the emerging codes. Using this method, our aim is to develop a theoretical model based on the gathered data. The credibility of the results will be determined by triangulation, where three members of the research team will perform the analysis independently.