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Due to an unhealthy lifestyle, individuals with schizophrenia are at higher risk of morbidity compared to the general population. Studies have shown that physical activity can have positive effects on physical and mental health in these patients. The aim of the study was to evaluate the effects of a physical activity intervention on symptoms of schizophrenia, as well as on a number of physical and mental health variables. The aim was also to gain more understanding of the participants´ experience of the intervention with interviews.Seventeen individuals between the ages of 21-31, diagnosed with schizophrenia participated in the study. They exercised under professional supervision for a minimum of two sessions per week for 20 weeks and attended weekly lectures on a healthy lifestyle. The participants answered standardized questionnaires (PANSS, DASS, Rosenberg, CORE-OM, BHS, QOLS), and physical measurements (weight, height, body mass index, resting blood pressure, waist circumference and resting heart rate) were taken before and after the intervention. Six participants were interviewed after the intervention and asked about their experience.Negative and general psychiatric symptoms, depression, anxiety and stress scores decreased significantly whereas well-being, quality of life and physical activity increased (p0.05). Apart from resting heart rate that decreased (p0.05), physical measurements remained unchanged at the end of the intervention.The participants´ physical activity increased, their mental well-being improved, and they did not gain weight during the intervention period. Regular exercise under supervision and education about a healthy lifestyle are a beneficial adjunct to the primary treatment of people with schizophrenia.

Cardiac rehabilitation is a well-established treatment for patients with coronary artery disease but limited information is available for Icelandic patients. The aim of this study was to investigate whether Phase II cardiac rehabilitation at the HL rehabilitation center was improving physical health and quality of life of patients.Patients that had undergone coronary artery intervention were invited to participate. There were 64 participants (of 65 invited) that started in the study and 48 that finished. On average participants attended 2.1 sessions pr. week, for 8.4 weeks. Measurements performed: endurance (W/kg), blood pressure and pulse responses from an exercise test and body mass index (kg/m2). To measure health related quality of life the SF-36v2 questionnaire was used.Endurance improved by 14.4% (p0,001) and a 6.1% increase was seen in peak pulse (p=0.001). The group was divided by age (32-64 years and 65-86 years) and both age groups improved their endurance number similarly (14.6% and 14.1%) but only the older age group improved peak pulse significantly or 7.2% (p=0.007). When the group was divided according to number of training sessions per week there was a 10.1% increase in endurance in the group that had fewer sessions but it was 19.8% in those that attended more sessions (p0.001). Participants assessed that their physical health, measured with a questionnaire, had improved at the end of training (p=0.003). When the group was divided into two groups according to how they measured their physical health at the beginning of the study there was a significant increase of 15.1% in physical health in those that estimated worse quality of life at the beginning of the study, but the other group had an increase of 1.2%.Cardiac rehabilitation improves endurance and physical wellbeing in patients. Training magnitude is essential for improvement.

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).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.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).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.

Background: Insufficient sleep is associated with an increased risk of a variety of negative health outcomes and has been shown to adversely affect academic and cognitive function. Despite strong evidence of the deleterious effects of short and disrupted sleep on health, studies that use objective methods to measure adolescent free-living sleep, in general, and its association with academic and cognitive performance, specifically, are scarce, particularly during the critical transition from compulsory to secondary education. Aim: The aim of this research was to use objective measures to quantify the free-living sleep of Icelandic adolescents at ages 15 and 17, as they transition from compulsory to secondary education, and to determine whether their sleep patterns are associated with academic and cognitive outcomes. Methods: The study sample came from six elementary schools in Reykjavík, Iceland. One week of free-living sleep measured with wrist actigraphy was collected at two time points. The first wave of data collection occurred in 2015, where 280 participants had valid sleep data (mean age 15.9±0.3 years). Two years later, 199 participants had valid sleep data (mean age of 17.7±0.3 years). In total, 145 participants had complete data at both data collection points. During the first wave of data collection, academic achievement was objectively quantified using the combined score from standardized national examinations administered to all 10th grade students in mathematics, English, and Icelandic. During the second wave of data collection, an n-back working memory task and Posner cue-target visual attention task were used to objectively assess cognitive function. Results: Over all measured nights at both time points, Icelandic adolescents averaged late bedtimes (00:43 at age 15, 01:12 at age 17), short total sleep time (6.6 ± 0.7 h/night at age 15 and 6.2 ± 0.7 h/night at age 17) and high variability in total sleep time (weekly standard deviations of 1.3 h and 1.4 h at ages 15 and 17, respectively). Thus, during the two year change from age 15 to age 17, students sleep duration decreased, night-to-night variability in sleep duration increased, and students went to bed 29 min/night later. Cross-sectional regression of the data collected at age 15 in those with standardized exam scores (n=253) demonstrated that both bedtime and night-to-night variability in total sleep time were negatively associated with the average score across all topics. Similarly, cross-sectional analysis of students who underwent cognitive function testing at age 17 (n=160) showed that time in bed the night before cognitive testing was negatively associated with response times during the most challenging memory task. However, sleep measures the night before did not correlate with performance on the attention task and weekly sleep parameters were not associated with either cognitive task. Conclusion: In general, Icelandic students go to bed late and have short and inconsistent sleep schedules at both age 15 and age 17. Cross-sectional results at age 15 indicate that those with earlier bedtimes and more consistent sleep schedules score higher on national exams. In addition, the cross-sectional results at age 17 demonstrated that shorter time in bed the night prior to the cognitive testing was associated with poorer performance on the most challenging short-term memory task. Despite the presence of several significant associations, the relationship between free-living sleep and academic and cognitive task performance in healthy adolescents is less clear than that identified in laboratory studies or with self-report, perhaps due to high night-to-night sleep variation. Future studies with longer observation periods and interventional components could further clarify the relationship between free-living sleep and academic and cognitive performance in adolescents., Bakgrunnur: Fyrri rannsóknir hafa sýnt fram á að nægur svefn á unglingsárum er lífsnauðsynlegur, og að stuttur og ófullnægjandi svefn getur haft áhrif á andlega og líkamlega heilsu. Enn fremur hefur verið sýnt fram á að stuttur svefn getur haft neikvæð áhrif á námsárangur og hugræna virkni. Þrátt fyrir sterkar vísbendingar um skaðleg áhrif ófullnægjandi svefns á heilsuna skortir rannsóknir sem mæla svefn hlutlægt (við frjálsar aðstæður). Einnig skortir rannsóknir sem nota hlutlægar mælingar til að kanna tengsl svefns á námsárangur og hugræna frammistöðu, sérstaklega á þessum mikilvæga tíma þegar ungmenni færa sig úr grunnskóla og yfir í framhaldsskóla. Markmið: Meginmarkmið þessarar doktorsritgerðar var að nota hlutlæga mælikvarða til að mæla svefn íslenskra ungmenna á aldrinum 15 til 17 ára, við skólaskiptin úr grunnskóla yfir í framhaldsskóla, og að skoða hvort svefnmynstur þeirra tengist námsárangri og hugrænum þáttum. Aðferðir: Rannsóknarúrtakið kom frá sex grunnskólum í Reykjavík. Gögnum var safnað vorið 2015, þar sem 280 þátttakendur höfðu gild gögn um svefn (meðalaldur 15,9 ± 0,3 ár). Tveimur árum síðar höfðu 199 þátttakendur gild svefngögn (meðalaldur 17,7 ± 0,3 ár). Hægt var að tengja gögn hjá 145 nemendum á báðum tímapunktum. Svefn var mældur í eina viku með actigraph hreyfimæli sem var staðsettur á úlnliði. Í fyrri gagnasöfnun árið 2015 var meðaleinkunn í samræmdum prófum í íslensku, stærðfræði og ensku notuð sem mælikvarði á námsárangur. Tveimur árum seinna var hugræn virkni mæld með n-back minnisprófi og Posner cue-target athyglisprófi. Við mat á gögnum var notast við ýmsar tölfræðilegar greiningar, keyrðar í R tölfræðiforritinu. Niðurstöður: Íslensk ungmenni fara að meðaltali seint í rúmið (00:43 við 15 ára aldur, 01:12 við 17 aldur) og heildar svefntími er stuttur (6,6 ± 0,7 klst /nótt 15 ára og 6,2 ± 0,7 klst./nótt 17 ára). Enn fremur er breytileiki í svefni hár á báðum tímapunktum (1,3 klst./nótt og 1,4 klst). Þegar heildarbreyting á svefni frá 15 til 17 ára aldurs er skoðuð, sést að svefnlengd nemanda minnkar, svefnbreytileiki á nóttu eykst og nemendur fara að meðtali að sofa 29 mínútum seinna. Við fyrri gagnasöfnun, árið 2015 (n=253) fundust neikvæð tengsl á milli svefnlengdar, háttatíma og einkunna á samræmdu prófi sem gefur til kynna að nemendur sem fara fyrr að sofa og eru með minni breytileika í svefni fá hærri meðaleinkunn á prófunum. Svipað fannst í seinni gagnasöfnun árið 2017 (n=160), en þar sást að styttri tími í rúminu nóttina fyrir hugræna prófið tengdist slakari árangri, en þó aðeins á mest krefjandi minnisprófinu. Hins vegar voru ekki tengsl á milli svefns kvöldið áður og frammistöðu á athyglisprófinu og engin tengsl fundust á milli heildarsvefns yfir vikuna og niðurstöðum á minnis- og athyglisprófinu. Samantekt: Almennt fara íslensk ungmenni seint að sofa og svefnbreytileiki er hár bæði við 15 og 17 ára aldur. Að sama skapi styttist svefnlengd á tveggja ára tímabili þegar nemendur útskrifast úr 10. bekk og skipta yfir í framhaldsskóla. Þversniðsniðurstöður við 15 ára aldur sýna að svefngæði og háttatími hafa áhrif á einkunnir, en þeir nemendur sem fara fyrr að sofa og eru með lítinn breytileika í svefni fá hærri einkunnir í samræmdum prófum. Að auki sýndu niðurstöður við 17 ára aldur að styttri tími í rúminu nóttina fyrir hugrænu prófin tengdist slakari frammistöðu á mest krefjandi minnisverkefninu. Svefn virðist því hafa áhrif á hugræna þætti hjá 17 ára unglingum. Þrátt fyrir að fyrri rannsóknir hafi sýnt mikilvæg tengsl milli svefns og hugrænnar frammistöðu hjá heilbrigðum unglingum, virðast tengslin sem mælast hlutlægt vera óljósari en þau sem koma fram á rannsóknarstofu eða sem mæld eru með huglægum mælitækjum eins og spurningalistum. Ein skýringin getur verið mikill breytileiki í svefni hjá úrtakinu en framtíðarrannsóknir með lengri athugunartímabilum og íhlutunum gætu skýrt sambandið milli svefns og náms- og hugræns árangurs hjá unglingum enn frekar., Háskólasjóður Eimskipafélags Íslands, Rannsóknamiðstöð Íslands (RANNÍS)

Background Sleep and physical activity are essential functions of human health. According to International recommendations, adolescents should sleep 8-10 hours each night and engage in moderate to vigorous physical activity for at least 60 minutes per day for overall wellbeing. Previous studies have shown that during adolescence, sleep patterns change and most sleep studies up to date are based on subjective data for sleep duration and quality. Technological advancement in measurement of sleep and physical activity with objective measures adds value to the literature. Aim The main aim of the dissertation was to measure free-living sleep and physical activity in Icelandic youth at baseline (15 years) and two years later (17 years), and explore associations between sleep (duration, quality and timing), physical activity, and body composition. In addition, to compare sensitivity and agreement between subjective and objective measurements of sleep among and between ages of 15 and 17 years old. Methods The study sample came from six elementary schools in Reykjavík. Data was collected during spring 2015 among 315 participants at age 15. In 2017, follow-up data was gathered from 168 repeating participants at age 17. Data from one week of free-living sleep and physical activity was collected with accelerometers. Participants filled out a sleep diary to support accelerometer data and filled out a comprehensive questionnaire on sports participation, physical activity, mental health and parental education, etc. All measurements took place at the research lab (2017) or at individual schools (2015). Body composition was assessed at The Icelandic Heart Association with dual energy X-ray absorptiometry (DXA). Results The majority of adolescents did not get the recommended 8-10 hours of sleep per night according to accelerometer data. This especially applied during the school week (7 hours/night in bed, 6.2 hours/night actual sleeping, about 11% met the recommendation). In comparison, subjective self-reports estimated bedtimes about 1 hour earlier and two-year changes in self-reported bedtimes did not correlate with changes measured by accelerometry. While there was no association between recommended levels of physical activity and sleep measures, higher physical activity and lower day-to-day sleep variability were associated with lower fat percentage. Conclusions The thesis highlights patterns of sleep and physical activity in Icelandic youth, as they transitioned from age fifteen to seventeen. These are two modifiable behaviors of great importance for health. Most adolescents did not get enough sleep during school nights. This, together with insufficient physical activity, could negatively impact their future health. This study provides the foundation for future follow-up studies and potential targets for intervention studies, while serving as a reference for public health specialists, educators, and parents to support good sleep and activity practices., Bakgrunnur Svefn og hreyfing eru grundvallarþættir í heilsu mannsins. Alþjóðlegar svefn ráðleggingar fyrir ungmenni gera ráð fyrir 8-10 klukkustunda nætursvefni og að minnsta kosti 60 mínútna daglegri hreyfingu af miðlungs- eða mikilli ákefð til að viðhalda góðri heilsu. Á unglingsárum verða miklar breytingar á svefnmynstri einstaklinga en fyrri rannsóknir á svefni ungmenna hafa flestar byggt á huglægu mati á svefnlengd og gæðum svefnsins. Hlutlægar mælingar á svefni og hreyfingu bæta við þekkingu en fáar rannsóknir hafa beitt hlutlægum mælingum til skoðunar á þessum þáttum samtímis. Markmið Aðalmarkmið rannsóknarinnar var að mæla svefn og hreyfingu íslenskra ungmenna, við 15 ára aldur og aftur tveimur árum síðar (17 ára), í sínu náttúrulega umhverfi með hreyfimælum og rannsaka tengsl svefns (lengdar, gæða og tímasetningar) og hreyfingar við holdafar og efnaskiptaþætti. Að auki var næmni huglægra og hlutlægra mælinga á breytingum á svefni milli 15 og 17 ára aldurs borin saman. Aðferðir Úrtak rannsóknarinnar kom úr sex grunnskólum í Reykjavík. Gögnum var safnað á vormánuðum 2015 meðal 315 þátttakenda sem þá voru 15 ára. Árið 2017 var framkvæmd framhaldsrannsókn og gögn fengust frá 168 þátttakendum, þá 17 ára gömlum. Gögnum um svefn og hreyfingu var safnað með hröðunarmælum í eina viku. Þátttakendur fylltu út svefndagbók til hliðsjónar svefnmælingum og svöruðu spurningalista um íþróttaiðkun, hreyfingu, líðan, félagslega stöðu o.fl. Mælingar fóru allar fram á rannsóknarstofu (2017) eða í skólum þátttakenda (2015). Líkamssamsetning, mæld með tvíorku röntgengeisla-gleypnimælingu (dual energy X-ray absorptiometry, DXA) fór fram í Hjartavernd. Niðurstöður Fæst ungmennanna náðu að uppfylla ráðleggingar um a.m.k. 8 klukkustunda nætursvefn þegar svefn var mældur með hröðunarmælum. Þetta átti sérstaklega við á skóladögum (7 klst/nótt liggjandi í rúmi, 6,2 klst/nótt svefn, um 11% ná ráðleggingum). Huglægar mælingar tímasetningu á háttatíma voru um klukkustund fyrr en tímasetning metin með hröðunarmælum. Ekki fundust tengsl á milli huglægra og hlutlægra mælinga á breytingum á háttatíma frá aldrinum 15-17 ára. Þeir sem uppfylltu ráðleggingar um daglega hreyfingu sváfu ekki mælanlega lengur. Aukin hreyfing og minni breytileiki á svefnlengd tengdust lægri fituprósentu og kviðfituprósentu. Samantekt Samspil hreyfingar, svefns og holdafars var skoðað í úrtaki íslenskra ungmenna 15 og 17 ára. Niðurstöður rannsóknarinnar benda til þess að lífsstíll ungmennanna virðist ekki endurspegla viðmið opinberra aðila um daglega hreyfingu og svefn. Skoða þarf þá þætti sem hafa áhrif á svefnvenjur og þátttöku í daglegri hreyfingu svo bæta megi heilsu íslenskra ungmenna, en niðurstöður rannsóknarinnar nýtast sem þekkingargrunnur á stöðu svefns meðal ungmenna og grunnur fyrir íhlutunarrannsóknir sem hafa það markmið að bæta svefn og auka hreyfingu.

Background: The academic performance of children has been correlated with their future educational attainment and health and has therefore been viewed as a public health concern. Physical activity and cardiorespiratory fitness are known to exert many beneficial effects on the physical and mental health of children, but the relationship with academic performance remains unclear. The relationship between adiposity and academic performance also remains inconclusive. Aim: The main aim of this dissertation was to examine the associations between cardiorespiratory fitness, physical activity, adiposity and academic performance using cross-sectional and longitudinal data. Methods: This dissertation builds on data from three different studies. The first was a cross-sectional study conducted in 2003 titled Lifestyles of 9- and 15-year-old Icelanders, n = 448 subjects. The second study was a two-year cluster randomized intervention trial conducted between 2006 and 2008 on 7-year-old school children titled Lifestyles of 7 – 9-year-old children: intervention towards better health, n = 267 subjects. The third study was a follow up of the second study titled Longitudinal study of physical health status in a young Icelandic cohort (born in 1999): Interrelations with sleep and educational attainment, n = 321 subjects. Physical activity was measured by accelerometers and by a self-report instrument. Cardiorespiratory fitness was assessed by a cycle ergometer, and adiposity was determined by calculating the body mass index (BMI) and body fat percentage via a Dual Energy X-ray Absorptiometry (DXA) scan. The results from standardized testing retrieved from the Directorate of Education were used to assess academic performance. Results: No cross-sectional or longitudinal associations were identified between physical activity, cardiorespiratory fitness, and academic performance. Self-reported physical activity (frequency of sport participation) was associated with higher math performance in 9-year-olds. A long-term increase in adiposity level was associated with deteriorating academic performance in math, independent of changes in physical activity. Conclusions: An increase in adiposity from the fourth to 10th grades was accompanied by worsening academic performance. Further studies are required to identify factors that may negatively affect both changes in academics and body composition in school-aged children., Bakgrunnur: Sýnt hefur verið fram á að regluleg hreyfing, og í framhaldi þrek, hefur góð áhrif á heilsufar ungs fólks. Tengsl milli hreyfingar og námsgetu hafa verið rannsökuð en niðurstaðan er óljós. Það sama gildir um tengsl milli líkamsfitu og námsárangurs. Markmið: Að skoða tengsl hreyfingar, þreks og líkamsfitu við námsárangur hjá íslenskum börnum og unglingum. Aðferð: Stuðst var við gagnasöfn frá þremur íslenskum rannsóknum á lífsstíl og heilsufari þátttakenda. Þverskurðartengsl sem og langtímatengsl voru rannsökuð. Hreyfing var mæld með hreyfimælum en einnig sögðu þátttakendur sjálfir frá hve mikið þeir hreyfðu sig. Þrek var mælt með stigvaxandi hámarksprófi á þrekhjóli og líkamsfita var metin með líkamsþyngdarstuðli og hlutfalli líkamsfitu af heildar þyngd (DXA mæling). Niðurstöður úr samræmdum prófum voru notaðar til að meta námsárangur. Niðurstöður: Hvorki hreyfing né þrek reyndust hafa tengsl við námsárangur, hvorki í þverskurðarsniðið né langtímasniði. Þeir nemendur sem voru í offituflokki reyndust hafa lægri einkunnir en aðrir nemendur og aukning á líkamsfitu umfram meðaltal frá 9 -15 ára aldri tengdist lakari námsgetu. Ályktun: Aukning á líkamsfitu er áhættuþáttur gagnvart námsgetu barna og unglinga. Erfitt er að segja til um orsakasamhengi en frekari rannsókna er þörf á þáttum sem geta tengst báðum þáttum. Heildarhreyfing, mæld með hreyfimælum virðist ekki vera tengd námsgetu en við frekari flokkun á hreyfingu geta komið fram tengsli s.b.r. fjöldi íþróttaæfinga í viku.