The aim of this research study is to assess the effectiveness of an intervention on exercise and health, and to contribute to the understanding of how team-based worksite health promotion programs should be designed in order to increase and maintain exercise among employees. The study design is a randomized controlled trial.

There are a number of different theories on the subject of how to affect motivation for health behavior change. This study is based on the tenets of Self-Determination Theory (SDT) in combination with elements from Motivational Interviewing and in accordance with the Health Promotion Guidelines developed by the National Institute of Health and Clinical Excellence, NICE.

It is assumed that if such a program is designed and offered in a manner that satisfies the participants' sense of autonomy, competence and relatedness, this will affect the quality of the participants' self-regulated motivation and perceived competence for exercise and lifestyle changes. As a consequence, a large proportion of the participants will adhere to the program and increase their exercise both in the short (5 months) and long term (8 months).

The following research questions will be:

1. Would a team-based health and exercise promotion intervention designed to be needs supportive, relative to a control group:

   1. Influence increases in exercise levels, improved aerobic fitness, reduced blood pressure, and decreases in waist circumference, and Body mass index (BMI), in addition to changes in body composition in terms of reduced percentage of fat and increased percentage of muscles?
   2. Influence increases in psychological well-being?
   3. Influence increases in perceived investment in employees' health competence, which would positively predict affective organizational commitment and job performance, and negatively predict turnover intentions?
   4. Influence decreases in sickness absenteeism?

2. If so, would changes in psychological needs support, autonomous motivation for exercise, perceived competence and self-efficacy in exercise mediate these effects?

The principal contribution of this study is the understanding of whether and how a SDT-based intervention affects the participants' degree of autonomous motivation and perceived competence for exercise, and as a consequence behavioral change in the form of increased and regular exercise. That is, the psycho-social processes which are unfolding during the intervention, and caused by the intervention.

The intervention is implemented in a worksite setting and connected to a team-based health promotion program.

This is a cluster-randomized two-group trial that compares a group-based intervention with a control group. Cluster-randomization will be carried out at the level of physical location consisting of two work teams each.

Pre- and post-test assessments will be carried out during an individual health screening consisting of physiological tests and cross-sectional data collection in the form of quantitative and standardized questionnaires. The results are compiled in a health profile report. Participants are offered a 15-20 minutes individual consultation with the professional health advisor in order to explain the findings, answer quesdtions and giving healht recommendations.

A small collection of the questionnaires and some qualitative interviews will be applied in order to collect data on relevant variables during the intervention period as well as to assess fidelity and participants' perceptions of the intervention.

The intervention consists of three elements; two team-workshops, exercise support group meetings and a workbook for self-reflection and planning. The intervention will be carried out by two health advisors professionals (physiotherapist) trained in order to facilitate and lead the team-workshops in a need supportive manner.

Inclusion Criteria:

• Employment at the Norwegian Post
• Position of 40% or more

Exclusion Criteria:

• Temporary employment that lasts for less than 12 months