The study population will consist of cleaners performing predominantly cleaning in day-care institutions, offices, hospitals and schools. The cleaners are employed at one of the enrolled companies in the suburban area of Copenhagen, Denmark.
Inclusion criteria at company level were more than 50 employed cleaners, possibility for the cleaners to participate in the project-activities during paid working time and location of the company in the suburban area of Copenhagen. Inclusion criteria at participant level were employment as cleaning assistant for >
hours per week, being between 18 and 65
years of age, and giving signed, informed consent.
Exclusion criteria for participating in the intervention are employment
hours per week as a cleaning assistant, age below 18
years or above 65
years, declining to sign the informed consent, and pregnancy. Further, criteria of exclusion to specific physical tests are congestive heart failure, hospital admission for myocardial infarction or acute coronary syndrome within the last two years, hypertension (≥ 160/≥ 100
mmHg), angina pectoris, serious or chronic illness, severe trauma, frequent migraine, fever on the day of testing, and allergy to adhesive plasters for the diurnal measurements.
Data collection and study materials
Data collection will be conducted at three time points: At baseline, four and 12
months after baseline. The data collection will consist of a health check consisting of a questionnaire-based interview, physical testing of health and capacity-related measures, and objective diurnal measures of heart rate, physical activity, body position and blood pressure. At all time points, the questionnaire and the data collection will be conducted by test instructors blinded to the randomization of the participants.
The participant will get instant feedback from the physical testing in the health check, except for the venous blood sample, from a test-instructor. If some of the measured values are above the recommended levels from international and Danish health organizations [30
], the participant will be informed and encouraged to contact a physician.
A structured interview with validated measures will be conducted. The interview will involve sociodemographic measures i.e. sex, ethnicity, country of birth, occupational group, employment status and education [32
], lifestyle behaviour and health i.e. alcohol consumption, medicine use, parental history of cardiovascular disease, sleeping behaviour, level of physical activity in occupation and leisure [33
], general health, modified items of the Nordic questionnaires for the analysis of musculoskeletal disorders [34
], rate of perceived physical exertion [35
], items from Copenhagen psychosocial Questionnaire [36
], and items from the workability scale [37
Objective physical measures of weight, percent body fat, (Tanita BC418), height (seca model 213 1721009), body mass index (BMI), waist and hip circumference (WHR) (seca 201), a venous blood sample, blood pressure (Omron M6 comfort) and level of cardiorespiratory fitness by a sub-maximal step test.
Weight and percent body fat will be estimated by a Tanita BC418. Measurement will be made while the participant is wearing light clothes and no shoes. Estimated weight of clothes (1.5
kg) will be subtracted from body weight. Percent body fat will be estimated by bio-electric-impedance-analysis from electricity running from foot to foot and hand to hand [38
]. Height will be measured while the participant is standing looking straight forward and wearing no shoes. Calculation of BMI by the equation of BMI
(body weight (kg)/body height (m2
]. Waist and hip circumference will be measured while the participant wears light clothes and is standing looking straight forward. The waist is defined as the narrowest point between the lowest rib and the iliac crest [30
]. The WHR is calculated by waist circumference (cm)/hip circumference (cm). A 25
ml blood sample will be drawn from the vena brachialis by a bio-analyst. Blood pressure will be measured on the left upper arm after 15
minutes of sitting at rest. Level of cardiorespiratory fitness will be estimated by a sub-maximal step test. The step test is conducted on a bench of 30
cm height for females and 35
cm for males. The step frequency is increased from 0.2 steps per second to maximal 0.8 steps per second, at the maximal 6
minutes of testing time. The step test is terminated when the participant is unable to follow the rhythm of the steps or unable to extend the knee properly.
Diurnal measurements of heart rate, physical activity, body position and ambulatory blood pressure will be conducted after each health check. Heart rate, physical activity and body position will be measured over four days and during both working and non-working days. Ambulatory blood pressure will be measured over 24
hours on a day including work. Cleaners will be instructed to write a log of working hours, sleeping and waking time and time periods spent without monitors. Cleaners will be given practical information about how to wear and treat the monitors.
The diurnal measurements of heart rate will be performed with Actiheart [40
], to assess type of physical activity and body position the Actigraph GT3X
] will be used and for ambulatory blood pressure the Spacelabs 90217 [42
Actiheart measures electrocardiographic raw signals with a sensitivity of 0.25
mV. Heart rate is calculated by the interbeat intervals between the R peaks in the QRS complex. Actiheart is initialised by the height, weight, gender and age of each participant. Actiheart is validated for measurement of heart rate, heart rate variability and estimation of energy expenditure in the field [43
]. Actiheart will be mounted with ag-ag-cl pre-gelled electrodes (Ambu blue sensor VL-00-S/25) at one of the validated positions at the apex of sternum with a horizontal wire to the right at the level of the 5th
intercostal space or at the manubrium of the sternum with a horizontal wire to the right at the level of the 2th
intercostal space [46
Actigraph measures accelerations in 3 dimensions with a dynamic range of
G, sampled with a precision of 12 bit. Actigraph is validated for estimation of type of physical activity in the field [47
]. The accelerometers are initialised for recording and data downloaded using the manufacturer’s software (ActiLife version 5.5). Four Actigraphs will be mounted on the skin with adhesive tape (3
M, Hair-Set, double sided adhesive tape and Fixomull, BSN medical) at the level of T1-T2, 3
cm distal to the deltoid insertion on the dominant arm, laterally to and below the iliac crest [48
] and on the right thigh at the most muscular part of the quadriceps femoris, medial to the iliac crest and the top of the patella, orientated with the x-axis pointing downwards, y-axis horizontally to the left and z-axis horizontally forward. The Actigraph signals will be sampled at 30
Hz, and processed to derive the amount of steps, type of physical activity (e.g. walking, climbing stairs, running, arms above shoulder height, bending of the spine), and body positions (e.g. standing, sitting and lying) [45
Spacelabs measures ambulatory blood pressure by oscillometry. Spacelabs is validated for measurement of blood pressure in the field [49
]. The Spacelab monitor will be mounted on the non-dominant upper arm with a tube connecting the sampler to the cuff. The sampler is mounted with elastic straps around the waist. Spacelabs will be used to monitor the ambulatory blood pressure over 24
hours, with a frequency of every 20
minutes during waking hours, and measurements every 40
minutes during sleep [50
From the diurnal measurements the following analyses will be made; 1) the relative aerobic workload is calculated by the heart rate reserve (HRR), by the difference between the estimated maximal heart rate (HRmax
] and the sleeping heart rate, defined as the 10th
lowest recorded heart rate value during sleep (SHR) [53
– SHR). The HRR is similar to the percentage of VO2
max during whole body physical activity at group level [19
], 2) the monitored diurnal blood pressure over 24
hours, will be analyzed according to the guidelines for ambulatory blood pressure [49
], 3) the body position, level of physical activity and amount of steps and step frequency will be estimated [48
The health check data will be analyzed according to the listed outcomes; 1) cardiorespiratory fitness is estimated based on the step frequency and stepping time obtained at the sub maximal step test and qualified as poor, average or good [55
], 2) relative aerobic workload (% HRR), diurnal blood pressure and level of hsCRP [56
] and HDL [57
]. All data will be analyzed based on the intention-to-treat population, and as a per protocol analysis based on level of participation in the intervention activities.