The MILE Study: A Motivational, Individual and Locally Anchored Exercise Intervention Among 30-49 Year-olds With Low Levels of Cardiorespiratory Fitness. A Randomised Controlled Study in Primary Care.

Background It is well known that low levels of cardiorespiratory fitness are associated with a high risk of noncommunicable diseases and all cause mortality, and that improvements in cardiorespiratory fitness decreases this risk especially among the least fit (1-5). Although cardiorespiratory fitness has a genetic contribution, physical activity habits are the primary determinant of cardiorespiratory fitness in adults, and changes in physical activity levels result in changes in cardiorespiratory fitness (2,6). Thus the World Health Organization recommends adults aged between 18-64 to do at least 150 minutes of moderate-intensity aerobic physical activity or at least 75 minutes of vigorous-intensity aerobic physical activity weekly or an equivalent combination of moderate- and vigorous-intensity activity. In Denmark only an estimated 32 % fullfill these recommendations (7) and improving physical activity among this group of people is of great importance to public health.

In primary care several simple- and multicomponent physical activity interventions have been conducted in order to increase physical activity. However, the results of these interventions remain inconsistent. In addition, the content of the interventions is often unclearly described, particularly in relation to intensity and fidelity of the intervention delivery and reviews reveal how most of the studies use self-reported measures of physical activity (8,9). These issues warrant well-described intervention studies using objectively measures of physical activity and specifically designed for, and evaluated in primary care settings.

In Denmark, the "Check your health" programme is aimed at screening all individuals (n≈26,500) in the municipality of Randers aged between 30-49 years for cardiovascular disease during a 5-year period. Identifying people that are insufficiently active and people with a low cardiorespiratory fitness is one of the central objectives of the programme and this is done by self-reported and objective measures of physical activity and cardiorespiratory fitness.

To perform a successful intervention, strategies and techniques to motivate and guide people to adopt healthy choices need to be identified. Some of this may be accomplished by close supervision and personal instruction with healthcare professionals applying communication skills such as motivational interviewing (10,11), which has been found to be an effective approach to changing behaviour. This method specifically offers promise in improvement of cardiovascular health status (12).

Furthermore, a key issue will be to adopt modern technology and social media into the interventions (13). A Danish report supports this idea and concludes that particularly the 30-50 year olds, an age-group that does not always give high priority to regular physical activity due to lack of time and commitments such as job/further education and establishment of a family, are motivated by the social media and technology (14-16).