Organized leisure-time sport participation and academic achievement in preadolescents.

AIMS: The aims of this study were to study the correlation between lifestyle-related factors, such as organized leisure-time sport participation (OLSP), cardiorespiratory fitness, and adiposity, and academic achievement among preadolescents. METHODS: A cross-sectional study involving 248 nine-year-old school children was carried out. OLSP was self-reported with parental assistance, categorized as ≤ 1× a week, 2-3× a week, and ≥ 4× times a week or more. Academic achievement was estimated with results from standardized test scores in Icelandic and math. Cardiorespiratory fitness was estimated using a maximal cycle ergometer test. The sum of four skinfolds was used to estimate adiposity. RESULTS: Tests of between-subjects effect indicated that OLSP significantly correlated with achievement in math only (F(2,235) = 3.81, p = 0.024). Further analysis showed that the two less active groups had significantly lower scores in math compared to the most active group with OLSP ≥ 4× times a week or more (2-3× times a week, unstandardized coefficient (b) = -4.08, 95% confidence interval (CI) [-7.09, -1.07]; ≤ 1× a week, b = -3.84, 95% CI [-7.59, -0.08]), independent of sex, age, maturity level (age to/from peak height velocity), family structure, and parental education. Neither cardiorespiratory fitness nor adiposity significantly correlated with academic achievements. CONCLUSIONS: The study's result indicates that frequent (four times per week or more often) sport participation is not harmful but may be beneficial to learning. However, further intervention-based study of this topic is needed to determine if this relationship is causal.

Physical activity during school and after school among youth with and without intellectual disability.

BACKGROUND: Little is known about physical activity (PA) among children with intellectual disability (ID) or their reasons to take part in PA and sport. AIMS: To investigate PA and PA patterns during school and after school among Icelandic children with mild-to-severe ID. METHODS AND PROCEDURES: Ninety-one children with ID and a matched group of 93 typically developed individuals (TDI) took part. PA was assessed with accelerometers and a questionnaire was used to collect data on PA behavior. RESULTS AND OUTCOMES: TDI children were more active and less sedentary than children with ID (p<0.001). Both sexes with ID were more active and less sedentary during school than after school (p<0.003) but no difference was found among TDI children. Children with ID (60%) were more likely to name weight loss as a reason to participate in PA than TDI children (34%, p=0.002) but a higher proportion (96%) of TDI children than children with ID (50%) participated in PA to improve skills (p<0.001). CONCLUSION AND IMPLICATIONS: Children with ID depend more on schools to accumulate their PA and their reasons for PA participation differ from TDI children. This needs to be considered when designing and implementing PA promotion campaigns for children with ID.

The relation between physical activity, fitness, and fatness in adolescents: A mediation analysis.

OBJECTIVES: To investigate the total, direct and mediated (by fatness) association of physical activity (PA) with fitness. METHODS: Body fat percentage (%Fat), maximal oxygen uptake (VO2max ) and PA were measured directly in 18-year-olds (n=202) and their association analyzed with a linear regression-based mediation analysis after controlling for sex. RESULTS: The total association between PA and VO2max was significant (c=0.66, P<0.001) and was significantly mediated by %Fat (ab=0.25, 95% CI: 0.04-0.49). The direct association was also significant (c=0.41, P<0.001). CONCLUSION: Physical activity is associated with VO2max in 18-year-old adolescents but a little over a third of that association is mediated by %Fat. Regardless of fatness, PA is important for fitness in this age group. Am. J. Hum. Biol. 28:584-586, 2016. © 2015 Wiley Periodicals, Inc.

The association of cardiorespiratory fitness to health independent of adiposity depends upon its expression.

BACKGROUND: The strong relation between cardiorespiratory fitness (CRF) and adiposity renders their independent associations to metabolic risk factors difficult to ascertain. AIM: To determine the associations of CRF and CRF relative to fat-free mass (CRFFFM) to total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, glucose, insulin and homeostasis model assessment (HOMA) and distinguish these relations from the association to adiposity. SUBJECTS AND METHODS: Anthropometrics, body fat percentage (%Fat) and fat-free mass (from dual energy X-ray absorptiometry) were measured in 127 (66 females) 17 and 23 year-olds. CRF from a maximal workload on a graded bicycle test and fasting blood samples were obtained. RESULTS: CRF was significantly related to total cholesterol, triglycerides, insulin and HOMA (r = -0.24 to -0.49, p < 0.03), as were all adiposity measures (r = 0.21-0.53, p < 0.05). Correcting CRF for %Fat rendered the relation to metabolic risk factors non-significant (p = 0.09-0.21); however, CRFFFM was significantly related to the metabolic risk factors (r = -0.25 to -0.32, p < 0.02). CONCLUSIONS: CRFFFM, where adiposity has been removed, is associated with metabolic risk factors, whereas CRF, which is related to adiposity, is not after adjustment for fatness. Previously, independent effects of CRF on health may have been underestimated by using an expression of CRF strongly related to the adiposity measures.

[Prevalence of sport injuries, sport participation and drop out due to injury in young adults]. / Algengi íþróttameiðsla, íþróttaþátttaka og brottfall vegna meiðsla hjá 17 og 23 ára ungmennum.

INTRODUCTION: Sport participation has increased during the past few decades, with accompanying rise in sport injuries. The purpose of this study was to assess the prevalence of sport injuries, and drop-out due to them along with possible risk factors (hours of sports participation, sex, age, aerobic fitness and body composition). MATERIAL AND METHODS: A retrospective, cross-sectional design was used and the 457 participants were 17 and 23 years old. Height, weight, body fat, lean soft tissue, bone mass, and aerobic fitness (W/kg) were measured. Participation in sports and physical training, and the prevalence of sport injuries and drop-out were estimated using questionnaires. RESULTS: Four hundred and forty participants (96%) had at some time point participated in organized sports, but 277 (63%) were no longer practicing, more commonly (p=0.058) among girls (67.6%) than boys (58.8%). Thirty-seven (8.4%) dropped-out due to sport injuries. Of those participating in organized sports for the past 12 months, 51% required medical assistance at least once because of sport injuries. Multiple regression analysis revealed 5-fold increased risk for requiring medical assistance among those practicing more than 6 hours per week compared to those who practiced 6 hours or less (OR=5.30, 95% CI: 3.00 to 9.42). CONCLUSION: Youth sport injuries are a significant problem that can cause drop-out from participation in sport. More research is needed to better understand the impact of risk factors in order to promote prevention and ensure evidence-based training.

Fatness but Not Fitness Relative to the Fat-Free Mass Is Related to C-Reactive Protein in 18 Year-Old Adolescents.

INTRODUCTION: The interaction between fatness, fitness, and C-reactive protein (CRP) in adolescents is not well characterized but may be important to prevent low grade inflammation. The purpose of this study was to assess the relationship between adiposity, different expressions of fitness, and CRP in late adolescence using direct measures of fitness and fatness. METHODS: Anthropometric measurements were taken on 245 eighteen-year-old participants (116 girls). Fasting CRP, glucose, and insulin were measured and homeostatic model assessment (HOMA) calculated. Body composition was estimated via dual energy X-ray absorptiometry. Fitness was assessed with maximal oxygen uptake (VO2max) during a treadmill test and also expressed relative to the fat-free mass (VO2maxFFM). RESULTS: Prevalence of overweight/obesity based on body mass index (BMI) was 20.7% and 25.6% among girls and boys, respectively (p = 0.407), but 42.5% and 58.1% when based on body fat percentage (%fat, p = 0.015). Higher proportion of boys (81.3%) than girls (54.5%) were highly fit (p<0.001), but the percentage of girls with high levels of CRP was greater (12.1% vs 6.2%, p = 0.028). Adiposity, indicated with BMI, waist circumference, fat mass, android fat mass (aFM), or %fat, was positively associated with CRP independent of VO2max (r = 0.13-0.18, p<0.05) and VO2maxFFM (r = 0.24-0.32, p<0.001). VO2max, was negatively associated with CRP independent only of BMI and waist circumference (r = -0.21, p = 0.001), but not %fat, fat mass or aFM (r = -0.08 to -0.12, p>0.05). VO2maxFFM was unrelated to CRP with (r = -0.07 to -0.11, p>0.05) or without (r = -0.10, p = 0.142) adjustment for adiposity. Additional adjustment for HOMA did not change any of the relationships, although the coefficients were attenuated. CONCLUSIONS: Fatness has a greater association with CRP than fitness in late adolescence. However, VO2maxFFM, which is truly independent of adiposity, is unrelated to CRP, indicating that the effects of fitness might be mediated via the fatness component embedded in fitness expressed relative to body mass.

[Physical activity and physical condition of Icelandic primary and secondary school children with intellectual disability]. / Hreyfing og líkamlegt ástand íslenskra grunnskólabarna med proskahömlun.

INTRODUCTION: Little is known about physical activity, body composition and metabolic risk factors among children with intellectual disability (ID). The purpose of this study was to investigate their physical condition. MATERIAL AND METHODS: Children with ID (n=91) and a randomly selected age-and-gender matched group of 93 typically developed individuals (TDI) participated and the groups were compared on physical activity, fitness, body composition, blood pressure, blood lipids, and glycemic control. RESULTS: Children with ID were shorter (-8.6 cm, p<0.001), had greater skinfolds (p<0.001), diastolic blood pressure (22.7 mm, p=0,006), and body fat percentage (4.0 percentage points, p=0.008) than TDI children. Boys with ID had larger waist circumference than TDI boys (6.3 cm, p=0.009) but no difference was found among the girls. Higher proportion (41%) of children with ID than TDI children (19%) were categorized as obese (p=0.006) based on body fat percentage. No children with ID reached the recommended daily 60 minutes of moderate- to vigorous physical activity compared to 40% of the TDI children. Only 25% of children with ID achieved the recommended levels for fitness, whereas the same proportion was 75% among TDI children. Over 20% of the children with ID had elevated waist circumference, 34% elevated blood pressure, 13-21% elevated metabolic risk factors in the blood, and 7% were diagnosed with metabolic syndrome. These prevalences were lower among the TDI children. CONCLUSION: Physical condition of children with ID is poor and inferior to their TDI peers. Further studies are needed to investigate the reasons underlying the poor physical health among children with ID and how it can most effectively be enhanced.

[Physical activity and its relation to metabolic and cardiovascular risk factors among three professions]. / Hreyfing þriggja starfsstétta og tengsl hennar við ahættuthætti efnaskiptasjúkdóma og hjarta- og æðasjúkdóma.

INTRODUCTION: The relation between objectively measured physical activity (PA) and metabolic and cardiovascular risk factors has not been studied in Iceland. This study aimed to investigate PA and metabolic and cardiovascular risk factors among three professions: manual laborers, office workers, and farmers. MATERIAL AND METHODS: The participants (73 males, 89 females) underwent anthropometric measurements. Total PA and time spent in moderate-to-vigorous PA (MVPA) was assessed with activity monitors. Blood pressure was measured and fasting blood samples analyzed for total cholesterol, low- and high-density lipoprotein cholesterol, triglycerides, glucose, insulin and homeostatic model assessment. RESULTS: Male manual laborers and farmers were more physically active than office workers (p<0.01), but no difference was found among females. Nevertheless, female farmers spent less time in MVPA than other professions (p%lt;0.05). Low proportion (18.4%) of all participants and none of the male office workers met the guidelines of the Directorate of Health for daily PA. Farmers had lower levels of triglycerides (p=0.01) and glucose (p<0.01), and greater fat-free mass (p<0.03) than other professions. They also had the highest levels of high-density lipoprotein cholesterol, followed by manual laborers, and then office workers (p<0.02). Total PA was significantly related to a greater number of metabolic risk factors than time spent in MVPA. CONCLUSION: Farmers have the most favorable metabolic and cardiovascular risk factors in the blood and their PA and fat-free mass are a likely explanation. Regardless, their PA is low, and only one-fifth of all participants meet the guidelines for daily PA. Total PA appears more important for the metabolic and cardiovascular risk factors than time spent in MVPA.

Gender differences in development of mental well-being from adolescence to young adulthood: an eight-year follow-up study.

BACKGROUND: The transition from adolescence to young adulthood is marked by many changes. Mental well-being plays an important role in how individuals deal with these changes and how they develop their lifestyle. The goal of this study was to examine gender differences in the long-term development of self-esteem and other mental well-being variables from the age of 15 to the age of 23. METHODS: A baseline measurement was performed in a nationwide sample of 385 Icelandic adolescents aged 15, and a follow-up measurement was conducted eight years later, when participants had reached the age of 23. Standardized questionnaires were used to measure self-reports of self-esteem, life satisfaction, body image, anxiety, depression and somatic complaints. RESULTS: Women improved their self-esteem significantly more than men from the age of 15 to 23 (p=0.004). Women were more satisfied with their life than men at the age of 23 (p=0.009). Men had a better body image, less anxiety, less depression and fewer somatic complaints than women, independent of age. Across gender, anxiety declined and somatic complaints became fewer (p<0.05). CONCLUSIONS These findings suggest that gender differences in mental well-being factors, favouring men, found in adolescents, are not as long-lasting as previously thought. Women improve their mental well-being from adolescence to young adulthood while men's mental well-being does not change.

Differences in physical activity among youth with and without intellectual disability.

INTRODUCTION: Very little is known about physical activity (PA) and PA patterns measured with objective methods among children with intellectual disability (ID). PURPOSE: This study aimed to investigate PA and PA patterns among Icelandic school children with mild-to-severe ID. METHODS: A sample of 91 children with ID and a randomly selected age- and sex-matched group of 93 typically developed individuals (TDI) took part in the study. Basic anthropometric measurements were attained, and PA was assessed with ActiGraph accelerometers for 7-10 consecutive days. A questionnaire was used to collect data on PA behavior. RESULTS: Although children with ID were 40% less physically active and spent 9% more time sedentary than their TDI peers, there was interaction between group and sex (P < 0.05). TDI boys were more active and less sedentary than TDI girls (P < 0.05), but no sex differences were found among children with ID on any PA variable. In addition, there was no difference between workday PA and weekend PA among children with ID. Only 16% of children with ID walked or biked to school, whereas the proportion was 74% among TDI children (P < 0.001). Similarly, a lower fraction (33%) of children with ID took part in 2 h·wk or more in sports compared with TDI children (76%, P < 0.001). No children with ID met the recommendation of 60 min of daily moderate-to-vigorous PA, whereas 40% of the TDI children met the recommendation. CONCLUSIONS: PA of children with ID is considerably lower than that among their TDI peers, and there seem to be no sex differences in PA and PA patterns among children with ID. The fact that no children with ID met the recommended daily MVPA calls for special PA measures in this group.

[The effects of 6 months' multimodal training on functional performance, strength, endurance, and body mass index of older individuals. Are the benefits of training similar among women and men?]. / Áhrif 6 mánaða fjölþættrar þjálfunar á hreyfigetu, vöðvakraft, þol og líkamsþyngdar stuðul eldri einstaklinga. Eru áhrif þjálfunar sambærileg hjá konum og körlum?

INTRODUCTION: Good functional performance in elderly people greatly improves their changes of independence and well-being. Conversely, bad functional performance can impair their capability of managing the activities of daily life.. The main goal of this study was to investigate the effects of a 6-months' multimodal training intervention on the physical performance of males and females, possible gender differences and the outcome 6 and 12 months after its completion. MATERIAL AND METHODS: This study examined 71-90 year old healthy seniors (n=117) participating in the AGES Reykjavik Study. It was a randomized and controlled cross-over trial, conducted in three 6-months' phases (time-points). After enrollment and baseline assessments, the study group was divided in two. Group 1 received 6-months' training while group 2 served as a control. In the second 6 months' phase, group 1 received no formal training while group 2 did. In the third phase, neither group received training. The groups' physical conditions were assessed after each phase. RESULTS: After 6-months' training, 32% improvement was seen in physical activity among males (p<0.001) and 39% among females (p<0.001). In physical performance, 5% improvement was seen for males (p<0.01) and 7% for females (p<0.001). Strength increased by 8% for males (p<0.001) and 13% for females (p<0.001). For both sexes, about 10% increase was seen in dynamic balance in the 8-foot up-and-go test (p<0.001) and 5-6% in walking distance for both sexes in the six minutes walking test (p<0.001). For both sexes, body mass index decreased by about 2% (p<0.001). No difference was seen between the sexes.in the training results. Both sexes retained long-term effects of the training on physical performance and dynamic balance for at least 12 months. CONCLUSIONS: Multimodal training intervention has positive effects on physical performance in older individuals, the sexes respond similarly to the training and retain achieved improvement for at least 12 months. The research indicates that moderate and systemic training for this age group could be a part of conventional health service for this age group.

[Physical activity of 9 and 15 year old Icelandic children - Public health objectives and relations of physical activity to gender, age, anthropometry and area of living]. / Líkamshreyfing 9 og 15 ára íslenskra barna í ljósi lýðheilsumarkmiða.

OBJECTIVE: The main objective of the study was to assess to what degree nine and fifteen year old Icelandic children followed the national physical activity (PA) guidelines for children set forth by the Icelandic Public Health Institute, which recommend no less than 60 minutes of moderate-to-vigorous physical activity a day (MVPA). MATERIAL AND METHODS: The study was conducted between September 2003 and January 2004 at eighteen randomly selected schools in the capital area of Reykjavik and towns and rural areas in the northeast. All nine years old (N=662) and fifteen years old (N=661) students were offered to participate. Half of the children were randomly chosen to partake in the PA part of the study where 176 nine-year-old and 162 fifteen-year-old children yielded usable data. We measured participants' height, weight and skinfold thickness and their PA by ActiGraph™ with respect to moderate-to-vigorous intensity (defined as counts >3400 cpm) and average volume. RESULTS: Only 5% of 9-year-old and 9% of 15 year-old students followed the recommended PA guidelines of at least 60 minutes a day of MVPA. MVPA was positively associated with sex (being a boy) and age, but negatively associated with skinfold thickness. Those living in the capital area of Reykjavik rather than in smaller towns and rural areas were likelier to accrue more minutes of MVPA per day. CONCLUSION: The results highlight the importance of developing PA interventions targeting children of school age. It is important to research and evaluate different ways as to how these interventions should best be conducted. Key words: physical activity, children, body composition, accelerometers.

Peak oxygen uptake in children: evaluation of an older prediction method and development of a new one.

The purpose of this study was to validate an equation that has been used to predict peak oxygen uptake (VO2peak) and, if invalid, to develop a new equation predicting VO2peak from performance on a cycle ergometer test. Forty-five 9- and 15-year-old children underwent a VO2peak test and were randomized into developmental (DEV) and cross-validation (C-V) groups. The equation under validation, which requires knowledge of resting energy expenditure (REE), underestimated VO2peak (p < .05), but once adjusted with a new parameter calculated in DEV, it cross-validated well (rYY' = .98, SE = .18 L . min-1). The accuracy of a new prediction equation built in DEV, not using REE, was confirmed in C-V (rYY' = .98, SE = .17 L . min-1) and the slope and intercept were not different from the line of identity (p < .05). VO2peak in schoolchildren can be predicted with good accuracy from an equation based on the whole sample [VO2peak = -1.5986 + 0.0115 . (maximal power output) + 0.0109 . (mass) + 0.1313 . (gender) + 0.0085 . (maximal heart rate)].