Vasculoprotective properties of plasma lipoproteins from brown bears (Ursus arctos)

Plasma cholesterol and triglyceride (TG) levels are twice as high in hibernating brown bears (Ursus arctos) than healthy humans. Yet, bears display no signs of early stage atherosclerosis development when adult. To explore this apparent paradox, we analyzed plasma lipoproteins from the same 10 bears in winter (hibernation) and summer using size exclusion chromatography, ultracentrifugation, and electrophoresis. LDL binding to arterial proteoglycans (PGs) and plasma cholesterol efflux capacity (CEC) were also evaluated. The data collected and analyzed from bears were also compared with those from healthy humans. In bears, the cholesterol ester, unesterified cholesterol, TG, and phospholipid contents of VLDL and LDL were higher in winter than in summer. The percentage lipid composition of LDL differed between bears and humans but did not change seasonally in bears. Bear LDL was larger, richer in TGs, showed prebeta electrophoretic mobility, and had 5–10 times lower binding to arterial PGs than human LDL. Finally, plasma CEC was higher in bears than in humans, especially the HDL fraction when mediated by ABCA1. These results suggest that in brown bears the absence of early atherogenesis is likely associated with a lower affinity of LDL for arterial PGs and an elevated CEC of bear plasma.

Reference values and secular trends for cardiorespiratory fitness in children and adolescents with obesity

AIM

To present specific reference values for cardiorespiratory fitness (CRF) in children with obesity and to analyse secular trends of CRF in the studied population.

METHODS

Cardiorespiratory fitness, the maximal oxygen uptake (VO₂ max), was estimated with the Åstrand-Rhyming submaximal bicycle test, in 705 Swedish children (356 girls, 8-20 years) with obesity according to the International Obesity Task Force (IOTF). Data were collected from 1999 to 2013. Secular trends, analysed with multiple linear regression, were adjusted for age, height and body mass index standard deviation score (BMI SDS).

RESULTS

All children had low CRF compared with normal weight standards but there was a marked variability of CRF in children with obesity, which was possible to quantify with the developed obesity specific CRF reference values. The mean value of absolute VO₂ max (L/min) increased with age and relative VO₂ max (mL/kg/min) decreased with age in both boys and girls. There was a negative secular trend in both sexes (P < .001).

CONCLUSION

These are the first obesity specific reference values of CRF in children enabling clinical evaluation in childhood obesity treatment. Cardiorespiratory fitness in children with obesity has declined the last decades, indicating that also within this vulnerable group physical activity has gone down.

No effects of a long-term physical activity intervention on executive functioning among adolescents

Objectives:

We investigated whether a school-based physical activity intervention would lead to improvements in working memory, inhibition and cognitive flexibility in adolescents aged 13–15 years.

Methods:

The adolescents at the active school (n = 108) participated in an intervention that included increased physical activity for 20 min/day, focused on aerobic activity with low cognitive demands for an entire school year. The adolescents at the control school (n = 59) received no extra physical activity. At the beginning (baseline) and end (follow-up) of the school year, the participants performed tests of executive function (working memory, inhibition and cognitive flexibility) and performed tests of physical fitness and health.

Results:

There was no change in executive functioning at follow-up when comparing the schools. However, only 46% complied with the intervention. When non-compliers were excluded from the analyses, the results remained the same, except for a small but significant increase in working memory for the active school as compared to the control school.

Conclusion:

These results indicate that compliance with the intervention was low and that aerobic exercise with low cognitive load does not produce improvements in executive functioning.

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.

Longitudinal study exploring factors associated with neck/shoulder pain at 52 years of age

OBJECTIVES

To investigate the ability of work-related measurements, body composition, physical activity, and fitness levels to predict neck/shoulder pain (upper body pain, UBP) at the age of 52 years. Another aim was to investigate the cross-sectional relationships between UBP, work-related factors, and individual factors at the age of 52 years.

METHODS

We followed a randomly selected cohort of 429 adolescents that was recruited in 1974 (baseline), when they were 16 years old. The participants completed physical fitness tests, questions about sociodemographic and lifestyle factors at 16, 34, and 52 years of age, and questions about work-related factors and pain in the follow-ups. Logistic regression analyses were used to examine the associations between UBP and the other variables.

RESULTS

Univariate logistic regression analyses showed that high body mass index and the work-related factors, low control, and low social support at the age of 34 years were related to UBP at the age of 52 years. For social support, there was an interaction between men and women where the relationship between low social support and the experience of pain was more evident for women. Among women, body mass index and social support remained significantly related in the multivariate analyses. For men, social support remained significantly related. Cross-sectional relationships at the age of 52 differed from the longitudinal in the sense that measures of joint flexibility and work posture were also significantly associated with UBP.

CONCLUSION

The fact that the cross-sectional differed from the longitudinal relationships strengthens the importance of performing longitudinal studies when studying factors that might influence the initiation of pain. UBP preventative measures might need to include both lifestyle (such as dietary habits and physical activity to ensure that the individuals are not becoming overweight) and work-related factors such as social support.

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.

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.

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.