Fysisk aktivitet, inaktivitet och kapacitet hos gymnasieungdomar

Sammanfattning: A change in behaviour with reduced physical activity and an increased sedentary behaviour among children and adolescents may be a threat to their future health. The literature shows that physical activity decreases through adolescence and the habits from childhood and adolescence have a tendency to become manifest. It is therefore particularly important to investigate the physical activity of adolescents and its effect on physical capacity, in conjunction with underlying factors that might have an impact on how active adolescents are. The overall aim of this thesis was to describe physical activity and its relation to physical capacity of adolescents from upper secondary schools and to highlight the reasoning about physical activity and health among physically inactive adolescents’. Paper I was a survey in which 884 adolescents from Northern Sweden participated. The adolescents were asked questions about their physical activity together with questions with a relation to physical activity. To put the physicalactivity in relation to physical capacity the adolescents were at the same time asked if they could participate in future studies concerning physical capacity (Paper II and III) and participation in an interview study (Paper IV). In paper IIIII physical capacity was assessed by aerobic capacity, muscle strength and balance (n = 99). In Paper II physical capacity was compared between physically active and physically inactive men and women. In paper III, the relation between physical capacity and self-rated physical activity and time spent sitting were investigated. In paper IV adolescents who did not meet the WHO recommendation of physical activity were interviewed and asked to describe their experience about physical activity and health. The results from paper I - III show that there was a group of adolescents who did not meet the recommendations for physical activity and that it affected their physical capacity. There was a clear gender difference; the men were physically active at higher intensity levels than the women. The men and women who estimated themselves to be physically active had significantly greater aerobic capacity, muscle strength (men) as compared to those who estimated themselves as physically inactive (according to WHO recommendations). The correlation between time spent sitting and physical activity was weak but still statistically significant for both sexes, and time spent sitting time did not appear to affect physical capacity. The results of the interviews in paper IV showed that physical inactive adolescents are aware of the health benefits of physical activity, yet they priorities performing other interests in leisure time. They described how both external and internal factors motivated them to be physically active. Further, the importance of the social context and that the activity had to be fun was considered reinforcing factor for performing physical activity. In summary, the results of the thesis show that there is a wide spread among adolescents in the level of physical activity and that there is a group of adolescents who do not meet the recommended levels. Also, there is a gender difference, where women are physically active at a lower intensity level. There was a weak correlation between sitting time and physical activity or physical capacity. Therefore it is important to both increase physical activity and reducing sitting time to prevent health related diseases. Factors that is important for influencing physical activity is the social context as parents, friends and environment.