Papers by Thorarinn Sveinsson
Journal of Orthopaedic and Sports Physical Therapy, May 1, 2011
Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, Jan 24, 2014
The purpose of this study was to assess activation patterns of medial (MH) versus lateral (LH) ha... more The purpose of this study was to assess activation patterns of medial (MH) versus lateral (LH) hamstrings in female athletes who had undergone ACL reconstruction (ACLR) using a hamstrings-graft during single-limb functional testing. Eighteen athletes (1-6 years since ACLR) and 18 healthy controls were recruited from the Icelandic women's top divisions in football, handball, and basketball. Activation of the MH and LH was monitored bilaterally using surface electromyography. Peak activation of the normalized signal was identified for two phases of the single-limb crossover (SLC) hop test and performance (distance jumped) registered. Self-reported knee symptoms and function were evaluated with the Knee injury and Osteoarthritis Outcome Score (KOOS). A repeated measures general linear model was used for main statistical data analyses, comparing variables of interests between limbs (within-subjects factor) and between groups. ACLR athletes had worse KOOS-symptoms scores (p < 0.05...
Journal of Orthopaedic & Sports Physical Therapy, 2011
Medicine and science in sports and exercise, 2016
International Journal for Equity in Health, 2015
Education and health constitute two interlinked assets that are highly important to individuals. ... more Education and health constitute two interlinked assets that are highly important to individuals. In Iceland, prevalence of dropout from secondary education poses a considerable problem. This 8-year prospective study assesses to what extent poor physical health and negative health-behaviors of Icelandic adolescents predict increased odds of dropout from secondary education. The sample included n = 201 Icelandic children who participated at age 15 (baseline) and again at age 23 (follow-up). Data included objective measurements of physical health and questionnaires assessing health-behaviors, education status, parental education, neighborhood characteristics, self-esteem, and depression. Independent t-tests and chi-square were used to assess differences in physical health and health-behaviors at follow-up stratified by education status. Ordinal regression models were conducted to assess whether physical health and health-behaviors at age 15 predicted increased odds of dropout from secondary education at age 23, independent of gender, parental education and psychological factors. At age 23, 78 % of girls and 71 % of boys had completed a secondary education. Completion of a secondary education was associated with significant health benefits, especially among women. Women without a secondary education had lower fitness, more somatic complaints, higher diastolic blood pressure, less sports participation, and poorer sleep, whilst men without a secondary education watched more television. In logistic regression models somatic complaints during adolescence were associated with 1.09 (95 % CI: 1.02-1.18) higher odds of dropout from secondary education in young adulthood, independent of covariates. Health-behaviors associated with higher dropout odds included smoking (3.67, 95 % CI: 1.50-9.00), alcohol drinking (2.57, 95 % CI: 1.15-5.75), and time spent watching television (1.27, 95 % CI:1.03-1.56), which were independent of most covariates. Finally, mother&amp;amp;amp;amp;#39;s higher education was strongly associated with significantly lower dropout odds (OR 0.54, 95 % CI: 0.34-0.88) independent of father&amp;amp;amp;amp;#39;s education and psychological factors, whilst high self-esteem was independently associated with lower dropout odds (OR 0.91, 95 % CI: 0.85-0.98). Completion of a secondary education yields substantial physical health benefits for young women, but not for men. Importantly, somatic complaints and negative health-behaviors among adolescent boys and girls adversely impact their educational outcomes later in life, and may have widespread consequences for their future prospects.
Mental Health and Physical Activity, 2015
Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, Jan 14, 2015
To identify cross-sectional and seasonal patterns of sleep and physical activity (PA) in communit... more To identify cross-sectional and seasonal patterns of sleep and physical activity (PA) in community-dwelling, older Icelandic adults using accelerometers. Seven-day free-living protocol as part of a larger population-based longitudinal observational-cohort study. Greater Reykjavik area of Iceland. 244 (110 female), older Icelandic adults (mean age 79.7±4.9 years). A subpopulation (n = 72) repeated the 7-day measurement during seasonal periods with greater (13.4±1.4 h) and lesser (7.7±1.8 h) daylight. None. Cross-sectional analyses using multiple linear regression models revealed that day length was a significant independent predictor of sleep duration, mid-sleep, and rise time (all p<0.05). However, the actual within-individual differences in sleep patterns of the repeaters were rather subtle between periods of longer and shorter day-lengths. Compared to women, men had a shorter sleep duration (462±80 vs. 487±68 minutes, p = 0.008), earlier rise time, and a greater number of awake...
Behavioural Brain Research, 2016
Many studies have examined the hypothesis that greater participation in physical activity (PA) is... more Many studies have examined the hypothesis that greater participation in physical activity (PA) is associated with less brain atrophy. Here we examine, in a sub-sample (n=352, mean age 79.1 years) of the Age, Gene/Environment Susceptibility-Reykjavik Study cohort, the association of the baseline and 5-year change in magnetic resonance imaging (MRI)-derived volumes of gray matter (GM) and white matter (WM) to active and sedentary behavior (SB) measured at the end of the 5-year period by a hip-worn accelerometer for seven consecutive days. More GM (β=0.11; p=0.044) and WM (β=0.11; p=0.030) at baseline was associated with more total physical activity (TPA). Also, when adjusting for baseline values, the 5-year change in GM (β=0.14; p=0.0037) and WM (β=0.11; p=0.030) was associated with TPA. The 5-year change in WM was associated with SB (β=-0.11; p=0.0007). These data suggest that objectively measured PA and SB late in life are associated with current and prior cross-sectional measures of brain atrophy, and that change over time is associated with PA and SB in expected directions.
International journal of obesity (2005), 2006
To investigate the prevalence and tracking of overweight and obesity in childhood cohorts born 19... more To investigate the prevalence and tracking of overweight and obesity in childhood cohorts born 1988 and 1994 in a population of high birth weight. Icelandic cohorts born in 1988 and 1994. Out of 1328, 9- and 15-year-old children from 18 randomly selected schools all over Iceland, 934 participated (71%). Height and mass were measured by the investigators. Also, height and mass at birth, and at age 2.5, 6, 9, and 12 years, were collected from maternity wards and school health registers. The prevalence of overweight children ranged from 10.1% for 2.5-year-olds to 18.7% for 9-year-olds. No difference was observed between the two cohorts or sex. The prevalence of obesity in the 1994 cohort (4.3%) was significantly higher (P = 0.01) at age 6 years, compared to the 1988 cohort (1.1%). The children who were overweight at age 2.5 years were more likely to be overweight at age 6 (OR=12.2) and 9 years (OR=4.9), but not significantly at age 12 or 15 years, compared with normal weight 2.5-year-o...
Scandinavian Journal of Public Health, 2015
International Journal of Pediatric Obesity, 2008
Introduction. In recent years, the prevalence of overweight and obese children has increased in I... more Introduction. In recent years, the prevalence of overweight and obese children has increased in Iceland, as in most Westernized countries. The main objectives of this study were to assess predictors of fitness and fatness of 9-year-old school children in Iceland. Methods. In total, 488 subjects (73.3% participation rate) from 18 randomly selected primary schools participated in this cross-sectional study. Height, weight, sum of four skinfolds and other anthropometric measures were performed on all children. Fitness was assessed via a maximal cycle ergometer test in 229 children and of those, 177 wore Actigraph accelerometers to measure physical activity over five consecutive days. Questionnaires regarding family background and lifestyle were completed by 361 mothers and 332 fathers. Results. The main findings from our study showed fatness, area of living and sex, as well as background variables, such as fathers' smoking and income, and number of sport practices attended per week were important predictors of fitness (best-fit model: R-sq 00.48, p B0.0001). In addition, parental body mass index (BMI), mothers' smoking and physical activity and children's objective measure of physical activity were found to be important predictors of children's fatness (best-fit model: R-sq 00.23, p B0.0001). Conclusion. These results provide information about predictors of fitness and fatness of 9-year-old children and emphasize the inverse association between the two. Further, our results suggest that mothers have a stronger influence on children's weight than fathers but the opposite may be true for fitness.
Medicine & Science in Sports & Exercise, 2014
Background: Sedentary behavior is associated with adverse health effects. Insights into associate... more Background: Sedentary behavior is associated with adverse health effects. Insights into associated determinants are essential to prevent sedentary behavior and limit health risks. Sedentary behavior should be viewed as a distinct health behavior; therefore, its determinants should be independently identified. Purpose: This study examines the prospective associations between a wide range of midlife determinants and objectively measured sedentary time in old age. Methods: Data from 565 participants (age 73-92 yr) of the AGESII-Reykjavik Study were used. Participants wore an accelerometer (ActiGraph GT3X) on the right hip for seven consecutive days. On average, 31 yr earlier (during midlife), demographic, socioeconomic, lifestyle, and biomedical factors were collected. Linear regression models were used to examine prospective associations between midlife determinants and sedentary time (G100 counts per minute) in old age. Results: After adjustment for sex, age, follow-up time, minutes of moderate to vigorous physical activity, body mass index, health status, mobility limitation, and joint pain in old age, the midlife determinants not being married, primary education, living in a duplex or living in an apartment (vs villa), being obese, and having a heart disease were associated with, on average, 15.3, 12.4, 13.5, 13.3, 21.8, and 38.9 sedentary minutes more per day in old age, respectively. Conclusions: This study shows that demographic, socioeconomic, and biomedical determinants in midlife were associated with considerably more sedentary time per day in old age. These results can indicate the possibility of predicting sedentariness in old age, which could be used to identify target groups for prevention programs reducing sedentary time in older adults. could be used to identify target groups for prevention programs aimed at reducing sedentary time and decreasing the risk of sedentary-related adverse health effects.
Medicine & Science in Sports & Exercise, 2007
Medicine & Science in Sports & Exercise, 2008
To explore the relationship between varying aerobic fitness (fitness), fatness, and fasting insul... more To explore the relationship between varying aerobic fitness (fitness), fatness, and fasting insulin levels in healthy children. A population-based sample of 9-yr-old (9YO, 47 boys, 56 girls) and 15-yr-old (15YO, 53 boys, 51 girls) Icelandic children. Body fatness was evaluated via body mass index, waist circumference adjusted for height (waist adj), and sum of four skinfolds. Fitness was assessed with a graded maximal cycle ergometer test. Fasting insulin was measured using an ECLIA. Fasting insulin correlated to all fatness measures (9YO, r = 0.43-0.46, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001; 15YO, r = 0.30-0.37, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.003) and fitness (9YO, r = -0.29, P = 0.003; 15YO, r = -0.32, P = 0.001). Adjustment for fitness did not affect the relations between fatness and fasting insulin in 9YO (r = 0.33-0.37, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001); however, only waist adj remained significantly related to fasting insulin (r = 0.24, P = 0.016) in 15YO. Children in the upper half of fitness and fatness split on the median did not differ in fasting insulin from children in the upper half of fitness but lower half of fatness. Fatness was related to fasting insulin in 9YO (r = 0.51-0.54, P = 0.001) and 15YO (r = 0.31-0.35, P = 0.011-0.028) in the lower half of fitness, but no association was observed in the upper half of fitness in either group. Fatness has a greater association with fasting insulin than fitness, especially among 9YO; however, fitness attenuates the adverse relation of fatness to fasting insulin in 15YO but does not change it in 9YO. In both age groups, being fitter and fatter does not result in greater fasting insulin than being fitter and leaner, and fatness is primarily associated with fasting insulin in lower-fit children.
Journal of Physical Activity and Health, 2014
Accelerometers have emerged as a useful tool for measuring free-living physical activity in epide... more Accelerometers have emerged as a useful tool for measuring free-living physical activity in epidemiological studies. Validity of activity estimates depends on the assumption that measurements are equivalent for males and females while performing activities of the same intensity. The primary purpose of this study was to compare accelerometer count values in males and females undergoing a standardized 6-minute walk test. The study population was older adults (78.6 ± 4.1 years) from the AGES-Reykjavik Study (N = 319). Participants performed a 6-minute walk test at a self-selected fast pace while wearing an ActiGraph GT3X at the hip. Vertical axis counts · s(-1) was the primary outcome. Covariates included walking speed, height, weight, BMI, waist circumference, femur length, and step length. On average, males walked 7.2% faster than females (1.31 vs. 1.22 m · s(-1), P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001) and had 32.3% greater vertical axis counts · s(-1) (54.6 vs. 39.4 counts · s(-1), P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001). Accounting for walking speed reduced the sex difference to 19.2% and accounting for step length further reduced the difference to 13.4% (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001). Vertical axis counts · s(-1) were disproportionally greater in males even after adjustment for walking speed. This difference could confound free-living activity estimates.
Journal of Fish Biology, 1995
ABSTRACT An experiment was conducted to test whether handling, anaesthesia or repeated formalin b... more ABSTRACT An experiment was conducted to test whether handling, anaesthesia or repeated formalin bathing had any effect on the growth rate in first feeding Arctic charr held in separate containers. The results show that these treatments had no effect on the growth rate.
International Journal of Behavioral Nutrition and Physical Activity, 2011
Background: Physical activity (PA) in children has declined in recent decades, highlighting the n... more Background: Physical activity (PA) in children has declined in recent decades, highlighting the need for effective intervention programs for school-aged children. The main objective of this study was to assess to what extent PA during and after school hours changed among children who received a progressive two-year long intervention vs. that of children who only received general curriculum-based PA.
Health Education Research, 2012
The aim of this study was to assess the effects of a 2-year cluster-randomized physical activity ... more The aim of this study was to assess the effects of a 2-year cluster-randomized physical activity and dietary intervention program among 7-year-old (at baseline) elementary school participants on body composition and objectively measured cardiorespiratory fitness. Three pairs of schools were selected and matched, then randomly selected as either an intervention (n 5 151) or control school (n 5 170). None of the effect sizes of body composition were statistically significant. Children in the intervention group increased their fitness by an average of 0.37 z score units more than the controls (95% CI:20.27 to 1.01, P 5 0.18), representing an improvement of 0.286 W/kg. Boys had higher fitness (mean diff 5 0.35 z scores, 95% CI: 0.13-0.58, P 5 0.001) than girls, independent of study group, fitness z score at baseline and body mass index. Post hoc analysis showed that the intervention school with the highest fitness z score change was significantly different from two of the lowest control schools (mean diff 5 0.83 z scores, 95% CI: 0.44-1.21, P < 0.0001 and mean diff 5 0.70 z scores, 95% CI: 0.29-1.10, P 5 0.01), but it was also significantly different from the lowest intervention school (mean diff 5 0.59 z scores, 95% CI: 0.19-0.99, P 5 0.05). The results of this intervention are inconclusive as regards to the effects on fitness, but the inter-vention did not have any statistically significant effect on body composition.
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Papers by Thorarinn Sveinsson