How active are the Europeans in daily life?

The prevalence of obesity poses a serious public health problem. Low levels of physical activity in the population have been blamed to contribute to this pandemic. In spite of years of research, however, the relationship between physical activity and obesity is still not fully understood, especially among young individuals. Numerous physical activity intervention studies have failed to show an effect on the overweight and obesity. Maybe the currently used recommendations about increasing physical activity are wrong. A better understanding is needed about the art and degree of daily physical activity in the population in order to improve formulation of public health policy and recommendations, and maybe also what consumer policy actors can do in the fight against childhood and adulthood obesity.

Measuring physical activity at a population level is difficult due to the variety of definitions and methods that exist (3), as well as the complex nature of physical activity itself. Although self-reported physical activity has been commonly used for this purpose, the challenge of balancing methodological feasibility with measurement accuracy is further complicated by the problems inherent in self-reported measurements, such as reactivity, recall bias and social desirability bias (3). Progress has been made, such as the development of the International Physical Activity Questionnaire (IPAQ), to increase comparability in between countries (Craig et al, 2003). The IPAQ and has been used in above all Eurobarometer (2002, 2005), the WHO World Health Survey (2002), the International Physical Activity Prevalence Study (IPS), but limitations related to self-reported assessment methodology still remain. As objective instruments such as motion detectors, e.g. accelerometers, have been developed to overcome these problems, they may offer an accurate and feasible method of gathering detailed information on health enhancing physical activity (Troiano, 2007).
We have, using accelerometers, assessed levels of health enhancing physical activity as well as inactivity and their relationships with gender, age and body mass index (BMI) in a) an adult population, and b) among young individuals. The further development of the methodology is carried out within the frame of an EU-funded (DG SANCO) project ALPHA, Assessment of Levels of Physical Activity.

Daily life physical activity in an adult population

In total, 1114 adults (56% women, 45 +/- 15 years), randomly recruited from the Swedish population across a year, used an accelerometer (Actigraph MTI) for seven consecutive days (Hagströmer et al, 2007). The adults were active in at least moderate intensity activity for a median (intra quartile range) of 31 (18-47) min.day-1. Fifty-two percent accumulated 30 minutes per day of at least moderate intensity physical activity. Only seven percent achieved those 30 minutes from bouts of two minutes or more including one bout of at least 10 minutes. Average intensity, moderate and vigorous physical activity was lower with increasing age or BMI. Men spent more time than women in moderate and vigorous physical activity, but there was no gender difference in average intensity. The variation in inactivity could not be explained by gender, age or BMI.
In conclusion: Objectively obtained estimates of physical activity yielded lower values and a different activity pattern compared to those obtained by commonly used self-reports. This highlights the need to better understand the nature and measurement issues of health-enhancing physical activity of adults.

Physical activity, fitness and fatness among young individuals

In a series of studies within the European Youth Heart Study (EYHS) (e.g. Ruiz et al., 2006; Rizzo et al, 2007), we have clarified more in detail the relations between levels and patterns of physical activity, measured by accelerometry, cardiovascular fitness and fatness among children and adolescents, in about 1000 school-aged children, either 9 or 15 years old, in Sweden and Estonia. We observed that the intensity (especially vigorous intensity) of physical activity rather than the total amount (objectively assessed), may be important in relation to the prevention of obesity in children. These children spent on average 170 minutes hours of moderate physical activity per day, however the findings clearly indicated that moderate physical activity objectively assessed by motion detectors do not have any impact on the BMI or in the central adiposity. These results are in contradiction to those published in studies using self-reported measurements, which have been shown to have limited accuracy in children and adolescents.

Data from interventional studies have also failed in showing a positive effect of physical activity programs on body fat in children and adolescents. Due to the complexity of measuring physical activity in young people, the apparently obvious association between physical activity and fitness and fatness, has not been well established yet. Further research is needed to ensure reliable and efficient recommendations.

In Summary

To identify and prevent children and adolescents from risk of obesity, and to be able to evaluate effects of alternative intervention strategies among adults as well as young individuals, comparable physical assessment and fitness testing methodologies across Europe have to be developed, tested, agreed upon and also included in the health monitoring systems currently under development by the European Commission (DG SANCO; EUROSTAT, etc.). Efforts are being made in order to standardize and improve the assessment of physical activity and fitness in Europe in the ALPHA project, which main goal is to develop instruments for assessing levels of physical activity and related health determinants. Large-scale multi-centre studies such as the HELENA study (Healthy Lifestyle by Nutrition in Adolescence) are urgently needed in order to provide harmonised and comparable data through Europe.

References

1. Craig, Marshall, Sjöström, et al. International Physical Activity Questionnaire: 12 country reliability and validity. Med Sci Sports Exerc (2003) 35, 1381-1395

2. Hagströmer M, Oja P, Sjöström M. Physical activity and inactivity in an adult population assessed by accelerometry. Med Sci Sports Exerc. (2007) 39:1502-1508

3. Rizzo N, Ruiz J, Ortega F, Hurtig-Wennlöf A, Sjöström M. Relationship between features of metabolic syndrome and physical activity, fitness and fatness in Swedish children and adolescents. The European Youth Heart Study. J Pediatrics (2007) 150:388-394

4. Ruiz JR, Ortega FB, Rizzo NS, Villa L, Hurtig-Wennlöf A, Harro M, Oja L, Sjöström M. High Cardiorespiratory Fitness is Associated with Low Metabolic Risk Score in Children; The European Youth Heart Study. Ped Res (2007) 61:350-355

5. Troiano R. Large-scale applications of accelerometers: new frontiers and new questions. Med Sci Sports Exerc. (2007) 39:1501