Longitudinal changes in physical capacity from adolescence to middle age in men and women.

The aim was to investigate how physical capacity changes from adolescence through early adulthood to middle age with focus on early aging. The aim was also to study if physical capacity in middle age could be predicted by factors in adolescence or early adulthood. A cohort of men and women in Sweden (SPAF-1958, n = 425) have been followed for 36 years, at 16, 34, and 52 years of age. The study includes, among other variables, objective measures of physical capacity. At age 52, 50% of the original cohort participated in exercise testing. Physical capacity increased from 16 to 34 years. From 34 to 52 years, physical capacity decreased in both genders by 15-20% in all but one test. Physical capacity at 16 and 34 years of age were better predictors of physical capacity at age 52 than body dimensions, school grades and life style factors. In conclusion, present data confirm earlier cross-sectional studies regarding the decrease in aerobic capacity and muscular strength during the early ageing period in both genders. The study has also generated novel data that show a smaller decline in muscular endurance than previously reported. Finally, physical capacity is fairly stable from adolescence to middle age.

The Swedish physical activity and fitness cohort born in 1958 - dropout analysis and overview at 36-year follow-up.

The main aim of the Swedish physical activity and fitness cohort study (SPAF-1958) was to describe physical fitness, physical activity, health, and lifestyle across part of the lifespan, and to assess the influences on these factors from the environment, personal factors, and genetics. There is inevitable dropout from longitudinal studies, and it may be systematic. The aim of this first paper of the second follow-up of SPAF-1958 was to provide a dropout analysis to consider to what extent the participants, at 52 years of age, remain a representative sample of the original adolescent study population. Additional aims were to provide an overview of the study protocol and the ongoing study population. Ongoing study participants in SPAF born in 1958 were, at the second follow-up at the age of 52, still representative of the study cohort in terms of sex, adolescent geographical area, upper secondary school program, adolescent body composition, muscular strength, and muscular endurance. However, a higher physical activity and, among women, a higher aerobic capacity in adolescence decreased the risk for dropout. It is important when interpreting results from longitudinal studies to adjust for the systematic dropout that could bias the conclusions drawn from the results.

Nocturnal blood pressure non-dipping is prevalent in severely obese, prepubertal and early pubertal children.

AIM: To investigate the prevalence of nocturnal blood pressure dipping among obese prepubertal and early pubertal children and to analyse the relationship between dipping and measures of insulin-glucose metabolism or sleep-disordered breathing. METHODS: We studied 76 obese children (41% girls) under clinical care, with an average age of 10.4 ± 1.7 and a body mass index Z-score (BMI Z-score) of 6.2 ± 1.6. We performed a 24-h ambulatory blood pressure measurement. Non-dipping was defined as a nocturnal blood pressure reduction of <10%. We calculated measures of insulin-glucose metabolism from the performed frequently sampled intravenous glucose-tolerance test and from fasting blood samples. Overnight sleep polygraph recordings were performed to assess sleep-disordered breathing. RESULTS: Forty-two percent of the children were systolic non-dippers, and 17% were diastolic non-dippers. There were no associations between systolic or diastolic dipping and measures of insulin-glucose metabolism after adjustments for BMI Z-score, gender and pubertal status. There were no associations between dipping and measures of sleep-disordered breathing. CONCLUSION: Nocturnal non-dipping was two times higher among severely obese, prepubertal and early pubertal children, compared to previous reports among children in general. There were no associations between nocturnal dipping and insulin-glucose metabolism or measures of sleep-disordered breathing in this group.

Obese children without comorbidities have impaired microvascular endothelial function.

AIM: The aim was to test acetylcholine-induced endothelium-dependent vasodilatation in obese children without comorbidities, compared with normal weight controls, and to analyse associations between vasodilatation and other potential risk factors. METHODS: Endothelium-dependent vasodilatation was induced by transdermal iontophoresis of acetylcholine in 54 obese children (8.3-18.2 years old, 41% girls) and 44 normal weight controls (7.5-20.2 years old, 82% girls), and the subsequent change in perfusion was measured with laser Doppler flowmetry. In a subgroup of the obese children, associations between acetylcholine-induced vasodilatation and blood lipids, glucose/insulin metabolism, inflammation, 24-h ambulatory blood pressure (ABP), cardiovascular fitness and duration of obesity were evaluated. RESULTS: We found a lower endothelium-dependent vasodilatory response to acetylcholine in the obese children than the controls (p < 0.001). The peak perfusion response was 33% lower in obese children (p = 0.001). There was a trend towards lower vasodilatation in obese children with higher levels of triglycerides (p = 0.07). Children with the shortest duration of obesity exhibited the lowest vasodilatation (p = 0.03). No associations were found between 24-h ABP, cardiovascular fitness, inflammation and glucose/insulin metabolism. CONCLUSION: Obese children without comorbidities have significantly impaired microvascular endothelial function. The children who had been obese for a longer time seemed less affected.

Association between nocturnal blood pressure dipping and insulin metabolism in obese adolescents.

OBJECTIVE: The purpose of this study was to analyze the relationship between insulin-glucose metabolism, nocturnal blood pressure (BP) dipping and cardiac left ventricular mass (LVM) in obese adolescents without diabetes. METHODS: A cohort of 206 obese adolescents (mean age 15.4 years (s.d. 1.6), mean body mass index (BMI) 38 kg m(-2) (s.d. 5.8), 53% girls) under clinical care were included in the study. Body fat was assessed by dual X-ray absorptiometry (DEXA). Blood samples were drawn for analyses of fasting insulin (fS-insulin), fasting glucose and glycosylated hemoglobin Alc. Homeostatic model assessment index (HOMA index) was calculated. Insulin sensitivity and acute insulin response (AIR) were calculated from the performed frequently sampled intravenous glucose tolerance test. An ambulatory BP measurement was performed and 24 h daytime and nighttime values were calculated. Non-dipping was defined as a nocturnal BP reduction of <10%. Ultrasound was used to measure heart LVM and LVM index (LVMI) was calculated (LVM x height(-2.7)). RESULTS: Systolic non-dipping was present in 50% (n=103) of the subjects. Systolic and diastolic dipping was negatively associated with measures of insulin metabolism (HOMA index, fS-insulin and AIR). These associations were present independently of gender, age, daytime BP or body mass index standard deviation score. Dipping (P=0.7-0.9) or measures of insulin-glucose metabolism (P=0.3-1.0) were not associated with LVMI in this population. CONCLUSION: Non-dipping is common among obese adolescents. We found a negative association between nocturnal BP fall (dipping) and measures of insulin metabolism independently of the degree of obesity or daytime BP level among severely obese, non-diabetic adolescents without diagnosed hypertension. Our findings suggest the importance of keeping the insulin levels under observation even in allegedly healthy obese adolescents in clinical care, as a part of the prevention of morbidity associated with obesity.

Low physical activity among adolescents in practical education.

The aim of this study was to investigate physical activity levels and factors related to physical activity among 16-year-old girls and boys in secondary school practical and theoretical programs. An additional aim was to identify factors contributing to differences in physical activity patterns between the educational programs. Sixteen-year-old students in the first year of secondary school in Sweden (n=585) were systematically selected and 93% agreed to complete a questionnaire. Compared with students in theoretical programs, those in practical programs spent less time and energy per day in physical activity. Girls in practical programs were the least physically active, and boys in theoretical programs the most physically active students. Statistical analysis showed that, among students in practical programs, the influence of educational program on physical activity level was explained by lower socio-economic level, less parental support, lower perceived health level, and negative attitudes toward outdoor physical activities. These data suggest that promotion of physical activity should focus on students, especially girls, in practical programs. Because the difference in physical activity levels between educational programs was partly an effect of less positive parental influence, school-based programs may be especially influential in increasing physical activity levels among secondary school students.

Secular trends in sports: participation and attitudes among adolescents in Sweden from 1974 to 1995.

AIM: To study the secular trend (time changes) in participation in leisure-time sports activities and in attitudes towards sports activities and physical education in a representative sample of Swedish adolescents between 1974 and 1995. METHODS: A questionnaire was distributed to 16-y-old girls and boys (n = 395 in 1974, n = 542 in 1995) to assess participation in leisure-time sports activity, attitudes towards sports activities and attitudes towards physical education at school. Height and weight were measured and body mass index (BMI) was calculated. RESULTS: Compared with 1974, more subjects in 1995 answered that they were engaged in leisure-time sports activities, and that they were members of sports clubs. BMI increased from 1974 to 1995. By 1995, adolescents participated in and had become more interested in individual sports activities, including keep-fit activities (e.g. strength training and aerobics) compared with 1974. A gender difference in the feeling of anxiety towards physical education, with more girls experiencing it, appeared in 1995, but not in 1974. CONCLUSION: Although more adolescents participated in leisure-time sports activity in 1995 than in 1974, the lifestyle of adolescents between sports training sessions may have become more sedentary. This is negative in a health perspective, since the benefits of physical activity on health are largely correlated to the total energy expenditure. However, the increased interest in keep-fit activities is important, since these activities have the potential to be continued into adulthood.

Secular trends in body dimensions and physical fitness among adolescents in Sweden from 1974 to 1995.

AIM: To investigate changes over time in body dimensions, and muscular and aerobic fitness in a representative sample of 16-year-old-girls and boys in secondary schools in Sweden from 1974 to 1995 (n = 855). METHOD: Height and weight were measured and five tests were performed: run-walk, two-hand-lift, Sargent jump, sit-ups, and bench-press. RESULTS: In 1995, girls and boys had higher body mass index (BMI) than in 1974. Girls and boys performed less well in bench-press, sit-ups, and run-walk-tests in 1995. Boys, but not girls, performed better in Sargent jump in 1995 than in 1974. Girls and boys performed better in two-hand-lift in 1995 than in 1974. However, after adjustment for body dimensions, there were no differences in performance in two-hand-lift or run-walk-tests between 1974 and 1995. CONCLUSION: There was a decreased aerobic fitness and an increased maximal static strength among adolescents in Sweden between 1974 and 1995. These changes were partly due to increased BMI. However, decreased daily physical activity level cannot be excluded as a contributing factor to the decreased aerobic fitness. The reduced performance in muscular endurance in 1995 was not related to increased BMI. Instead, it is suggested that it is to be related to a specific decrease in hip flexion and arm muscle endurance.