Condition category
Circulatory System
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
Contrary to high occupational physical activity (physical activity at work), leisure time physical activity and exercise are well known to prevent cardiovascular disease and enhance cardiorespiratory fitness. The reasons for such differences are not well known. Cleaners represent a group with high occupational physical activity and a high risk of cardiovascular disease.
The aims of the study is to find out whether the participation in an exercise at work in order to improve cardiorespiratory fitness can reduce the risk factors for cardiovascular disease or affect the cardiovascular workload among cleaners. The aim is also to assess whether such an exercise can be successfully implemented at cleaning companies, with high participation throughout one year.

Who can participate?
Cleaners of either gender aged 18 – 65 years old will be invited to participate through their company. Participants that are pregnant or suffering from cardiovascular diseases, other serious or chronic illness, severe trauma or frequent migraine will not be able to participate. Participants who are allergic to band aids will be excluded from daily measurements.

What does the study involve?
The participants will be randomly allocated to either exercise or lectures for the whole period of the study. Participation involve three health checks and daily measurements. Health checks include measurement of height, weight, fat percent, blood pressure, cardiorespiratory fitness and a blood sample. Daily measurements include four 24-hour measurements of heart rate and physical activity, and one 24-hour measurement of blood pressure.

What are the possible benefits and risks of participating?
Participants will gain extra knowledge regarding their own health through either the exercise or the lectures. There are no known risks when criteria for participation are followed.

Where is the study run from?
The study is managed from the National Research Centre for the Working Environment in Denmark, Copenhagen.

When is the study starting and how long is it expected to run for?
The project started in August 2011 and is anticipated to end in August 2014. The participating companies will be involved in the study for the duration of approximately 14 months.

Who is funding the study?
The Danish Working Environment Research Fund and University of Copenhagen (Denmark).

Who is the main contact?
Mette Korshøj Larsen

Trial website

Contact information



Primary contact

Mr Andreas Holtermann


Contact details

Lersø Parkallé 105

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Cardiorespiratory fitness, cardiovascular workload and disease among cleaners: a cluster randomised worksite intervention


Study hypothesis

Baseline measurements
1. Cleaners with high cardiorespiratory fitness have lower cardiovascular workload (% of heart rate reserve) than cleaners with low cardiorespiratory fitness
2. Occupational physical demands (i.e. cardiovascular workload and upper body work) are positively related to diurnal ambulatory blood pressure

The four months intervention with aerobic exercise will:
1. Increase cardiorespiratory fitness
2. Decrease diurnal ambulatory blood pressure
3. Improve self-rated work productivity
4. Reduce rate of perceived exertion (RPE) during work
5. Improve metabolic cardiovascular risk factors
6. Reduce the need for recovery

A one year aerobic exercise intervention will:
1. Sustain cardiorespiratory fitness from measurements after 4 months
2. Successfully result in high long-term participation

Ethics approval

Committees on Biomedical Research Ethics of the Capital Region of Denmark, 10 November 2011 ref: H-2-2011-116

Study design

Cluster randomised controlled trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type

Quality of life

Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Aerobic exercise for prevention of cardiovascular disease among cleaners.


Participants will be randomised in clusters to receive one of the following interventions for one year. The clusters will relate to their work team where possible or groups where participants report to the same manager or work in close proximity.

Worksite aerobic exercise:
Supervised intervention at the worksite with aerobic exercise of 60 minutes duration parted in 2-3 weekly sessions are offered during the first four months of intervention. The amount of supervision is reduced during the last six months of the intervention, in which the participants are encouraged to continue with the exercise themselves.
The aerobic exercise will be aimed to be performed at an intensity of > 60% of maximal oxygen consumption. The types of aerobic exercise are tailored to the specific worksite through a modified intervention mapping approach, including organisation, leaders and employees.

Reference group:
Receives 5 lectures concerning healthy living during the one year intervention period; none of the lectures will address physical activity.

Intervention type



Not Applicable

Drug names

Primary outcome measure

Cardiorespiratory fitness will be measured before the randomisation at baseline, after the 4 months intervention and after the 1 year intervention

Secondary outcome measures

1. Diurnal heart rate
2. Diurnal ambulatory blood pressure
3. Self-rated work productivity
4. RPE during work
5. Intensity and number of regions with self-rated musculoskeletal pain
6. High Sensitivity C-reactive protein (hsCRP)
7. High density lipoprotein (HDL)
9. Self-rated need for recovery
10. Participation in intervention

Measured before the randomisation at baseline, after 4 months intervention and after 1 year intervention

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Cleaning companies (> 50 employees)
2. Implementation of project activities during working hours

1. Working > 20 hours/week
2. Age 18 – 65 years old
3. Signed informed consent

Participant type


Age group




Target number of participants

120 participants

Participant exclusion criteria

Exclusion from physical tests:
1. Cardiac insufficiency
2. Acute myocardial infarction or acute coronary syndrome within the last few years
3. Hypertension (> 160/> 100 mmHg)
4. Serious or chronic illness
5. Severe trauma
6. Frequent migraine
7. Pregnancy
8. Fever

Exclusion from diurnal measurements:
1. Allergic to band aid
2. Pregnancy
3. Fever

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Lersø Parkallé 105

Sponsor information


Danish Working Environment Research Fund (Denmark)

Sponsor details

Landskronagade 33
+45 7012 1288

Sponsor type




Funder type


Funder name

Danish Working Environment Research Fund (Denmark)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

University of Copenhagen (Denmark)

Alternative name(s)

University of Copenhagen, KU

Funding Body Type

private sector organisation

Funding Body Subtype

Universities (academic only)



Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

1. 2012 protocol in
2. 2014 results in (added 23/01/2019)
3. 2015 of whether an aerobic exercise worksite intervention changes the level of inflammation biomarkers among cleaners. In (added 23/01/2019)
4. 2015 results of is aerobic workload positively related to ambulatory blood pressure? In (added 23/01/2019)
5. 2016 results of long term effects on risk factors for cardiovascular disease after 12-Months of aerobic exercise intervention. In ( added 23/01/2019)
6. 2016 results of the effect of an aerobic exercise intervention on cardiac autonomic regulation. In (added 23/01/2019)
7. 2016 results of does aerobic exercise increase 24-Hour ambulatory blood pressure among workers with high occupational physical activity? In (added 23/01/2019)
8. 2017 results of an aerobic exercise intervention targeting cardiovascular health, evaluated for its long term side effects on musculoskeletal pain. In (added 23/01/2019)
9. 2017 results of effects of 12 months aerobic exercise intervention on work ability, need for recovery, productivity and rating of exertion among cleaners. In (added 23/01/2019)

Publication citations

  1. Protocol

    Korshøj M, Krustrup P, Jørgensen MB, Prescott E, Hansen ÅM, Kristiansen J, Skotte JH, Mortensen OS, Søgaard K, Holtermann A, Cardiorespiratory fitness, cardiovascular workload and risk factors among cleaners; a cluster randomized worksite intervention., BMC Public Health, 2012, 12, 645, doi: 10.1186/1471-2458-12-645.

Additional files

Editorial Notes

23/01/2019: Publication references added