The effects of warm weather on children's outdoor heat stress and physical activity in a preschool yard in Gothenburg, Sweden.

Hot weather conditions can have negative impacts on the thermal comfort and physical activity of vulnerable groups such as children. The aim of this study is to analyze the effects of warm weather on 5-year-old children's thermal comfort and physical activity in a preschool yard in Gothenburg, Sweden. In situ measurements were conducted for 1-1.5 h in the early afternoon on 8 days in May, June, and August of 2022. The thermal comfort and physical activity was estimated with GPS-tracks, heart rate monitors, and step counts and compared to observed weather conditions. Results show that physical activity decreases under warmer weather conditions, depicted by a decrease in distance moved, step counts, and highest registered pulse. Moreover, on warm days, the children avoid sunlit areas. For 50% or more of the time spent in sunlit areas, the children are exposed to cautious levels of heat. In shaded areas, on the other hand, the children are less exposed, with five out of 8 days having 50% or more of the time at neutral levels. The study demonstrates the importance of access to shaded areas in preschool yards where children can continue their active play while simultaneously maintaining a safe thermal status.

Time Trends in Physical Activity Using Wearable Devices: A Systematic Review and Meta-analysis of Studies from 1995 to 2017.

INTRODUCTION: Conflicting evidence exists on whether physical activity (PA) levels of humans have changed over the last quarter-century. The main objective of this study was to determine if there is evidence of time trends in PA, from cross-sectional studies that assessed PA at different time points using wearable devices (e.g., pedometers and accelerometers). A secondary objective was to quantify the rate of change in PA. METHODS: A systematic literature review was conducted of English-language studies indexed in PubMed, SPORTDiscus, and Web of Science (1960-2020) using search terms (time OR temporal OR secular) AND trends AND (steps per day OR pedometer OR accelerometer OR MVPA). Subsequently, a meta-analytic approach was used to aggregate data from multiple studies and to examine specific factors (i.e., sex, age-group, sex and age-group, and PA metric). RESULTS: Based on 16 peer-reviewed scientific studies conducted between 1995 and 2017, levels of ambulatory PA are trending downward in developed countries. Significant declines were seen in both males and females (P < 0.001) as well as in children (P = 0.020), adolescents (P < 0.001), and adults (P = 0.004). The average study duration was 9.4 yr (accelerometer studies, 5.3 yr; pedometer studies, 10.8 yr). For studies that assessed steps, the average change in PA was -1118 steps per day over the course of the study (P < 0.001), and adolescents had the greatest change in PA at -2278 steps per day (P < 0.001). Adolescents also had the steepest rate of change over time, expressed in steps per day per decade. CONCLUSIONS: Evidence from studies conducted in eight developed nations over a 22-yr period indicates that PA levels have declined overall, especially in adolescents. This study emphasizes the need for continued research tracking time trends in PA using wearable devices.

A 20-Year Follow-Up Study of Objectively Measured Physical Activity.

BACKGROUND: The objectives of this study were to explore the effect of time, long-term tracking, and the proportion of objectively measured physical activity (PA) from early adolescence to the mid-thirties. METHODS: PA was measured as mean steps per day (SPD) with pedometers during 2000 (T1), 2003 (T2), 2005 (T3), 2010 (T4), 2016 (T5) and 2020 (T6). Data from 64 participants (n = 32 males) were analysed from their early adolescence (T1) to their mid-thirties (T6). RESULTS: SPD decreased in the total sample and among males and females (all, p < 0.001). Males took more mean SPD than females during T1 (p = 0.002), whereas females took more mean SPD during T2 (p = 0.009) and T6 (p = 0.008). Males' mean SPD tracked between T1 and T2 (p = 0.021), T2 and T3 (p = 0.030), T3 and T4 (p = 0.015) and T4 and T5 (p = 0.003). Females' mean SPD tracked between T3 and T4 (p = 0.024) and T5 and T6 (p < 0.001). In the total sample, more mean SPD were found on weekdays compared to weekend days at T3 (p = 0.017) and T5 (p < 0.001). CONCLUSIONS: SPD decreased between T1 and T6. Mean SPD tracked low-to-moderate in the short time span. From late adolescence to the mid-thirties, more mean SPD was observed during weekdays compared to weekend days.

Comparing self-perceived global self-esteem and physical self-esteem among children and adolescents in Southeastern Sweden, investigated in 2000 and 2017.

OBJECTIVES: To compare self-perceived global self-esteem (GSE) and physical self-esteem (PSE) among children and adolescents aged 11 and 14 years in Southeastern Sweden, investigated in 2000 and 2017. METHODS: The present study consists of two independent cross-sectional study-cohorts from Southeastern Sweden, investigated in 2000 and 2017. The same protocol, procedures, and instruments were used in 2000 and 2017. In October 2000, data for self-perceived GSE and PSE, and anthropometry were collected from 11-years old children (Grade 5) (n=74) and 14-years old adolescents (Grade 8) (n=84). In October 2017, children (n=186) and adolescents (n=140) from the same grade-levels, schools and classrooms provided data for the same variables as in 2000. GSE and PSE were assessed with the Children and Youth Physical Self-Perception Profile (CY-PSPP). RESULTS: Self-perceived GSE was higher in 2017 as compared to 2000 among both 11-years old boys (p<0.001) and girls (p<0.001) and 14-years old boys (p=0.008) and girls (p<0.001). Similarly, self-perceived PSE was higher in 2017 as compared to 2000 among both 11-years old boys (p<0.001) and girls (p=0.023) and 14-years old boys (p=0.025) and girls (p=0.002). CONCLUSIONS: Self-perceived GSE and PSE among children and adolescents aged 11 and 14 years in Southeastern Sweden were higher in 2017 as compared to 2000. These results are not in agreement with the increased psychological ill-health as being reported among children and adolescents during the last decade in Sweden.

Pupils' use of school outdoor play settings across seasons and its relation to sun exposure and physical activity.

BACKGROUND: Long outdoor stay may cause hazardous exposure to ultraviolet radiation (UVR) from the sun even at high latitudes as in Sweden (Spring to Autumn). On the other hand, long outdoor stay is a strong predictor of primary school children´s free mobility involving moderate to vigorous physical activity (MVPA). UV-protective outdoor environments enable long outdoor stay. We investigated the concurrent impact of different school outdoor play settings upon pupils´ sun exposure and levels of physical activity across different ages, genders, and seasons. METHOD: During 1 week each in September, March, and May, UVR exposure and MVPA were measured in pupils aged 7-11 years. Erythemally effective UVR exposure was measured by polysulphone film dosimeters and MVPA by accelerometers. Schoolyard play was recorded on maps, and used areas defined as four play settings (fixed play equipment, paved surfaces, sport fields, and green settings), categorized by season and gender. RESULTS: During the academic year, sport fields yielded the highest UVR exposures and generated most time in MVPA. In March, time outdoors and minutes in MVPA dropped and UVR exposures were suberythemal at all play settings. In May, green settings and fixed play equipment close to greenery promoted MVPA and protected from solar overexposure during long outdoor stays. CONCLUSION: More outdoor activities in early spring are recommended. In May, greenery attractive for play could protect against overexposure to UVR and stimulate both girls and boys to vigorous play.

School-based study showed a correlation between physical activity and smartphone and tablet use by students aged eight, 11 and 14.

AIM: This study investigated correlations between objectively measured physical activity (PA) and smartphone and tablet usage by sex and age in subjects aged eight, 11 and 14. METHODS: We recruited 549 children and adolescents (264 boys) from six schools in three middle-class communities in south-eastern Sweden. Steps per day were objectively measured using sealed pedometers and a brief daily questionnaire about smartphone and tablet usage. Correlations between mean steps per day and mean daily minutes of smartphone and tablet usage, and differences between low and high users, were investigated. RESULTS: There was a moderately inverse correlation between steps per day and smartphone and tablet usage in the total sample (r = -.329, P < .001), but it was lower in boys (r = -.340, P < .001) than girls (r = -.401, P < .001). When stratified further by both sex and age, this correlation was only found among 14-year-old girls (r = -.385, P < .001) and this group only, differences between low and high users (P = .005) were seen. CONCLUSION: There was a moderately inverse correlation between steps per day and smartphone and tablet usage. When stratified by both sex and age groups, this correlation was only observed in 14-year-old girls. The results may have implications for future PA interventions that target adolescent girls.

Comparisons of pedometer-determined weekday physical activity among Swedish school children and adolescents in 2000 and 2017 showed the highest reductions in adolescents.

AIM: This study compared differences in weekday physical activity among school children and adolescents in middle-class communities in south-eastern Sweden in 2000 and 2017. METHODS: Data were drawn from two independent cross-sectional cohorts of children and adolescents aged 8, 11 and 14. The same six schools, protocols, procedures and instruments were used in both years, with 332 subjects in 2000 and 562 in 2017. Mean steps per day (SPD) were measured with a Yamax SW-200 pedometer. RESULTS: The mean weekday SPD was similar among eight-year-old girls in both years, but 8% (p = 0.040) higher among eight-year-old boys in 2017. However, among 11-year-old children, the mean SPD were 12% lower among both girls (p = 0.033) and boys (p = 0.001). The SPD among 14-year-old adolescents were 24% (p = 0.012) and 30% (p < 0.001) lower among girls and boys, respectively. CONCLUSION: This school-based study from south-eastern Sweden showed that weekday physical activity differed between age groups in 2000 and 2017. The highest reductions were seen among older children and adolescents, particularly 14-year-old girls and boys. The only group that increased was eight-year-old boys, with no significant change in eight-year-old girls. A possible explanation might be the dramatically increased use of the Internet on phones and tablets.

Effects of an Empowerment-Based Health-Promotion School Intervention on Physical Activity and Sedentary Time among Adolescents in a Multicultural Area.

Physical activity (PA) decreases with age, and interventions are needed to promote PA during adolescence, especially, among those in low-socioeconomic status (SES) areas. The aim of this study was to investigate whether a two-year, empowerment-based health-promotion school intervention had any effects on changes in (a) moderate-to-vigorous PA (MVPA), (b) sedentary time (SED), (c) exercise training (ET) frequency, and (d) ET duration, among adolescents. Participants (aged 12⁻13 years at baseline) from one intervention school and two control schools, were recruited from a multicultural area of Sweden, characterized by low-SES. During the course of the two-year intervention, a total of 135 participants (43% boys) were included in the study. The intervention was developed and implemented as a result of cooperation and shared decision-making among the researchers and the participants. MVPA and SED were measured with accelerometers, and ET frequency and duration was self-reported at the beginning of the seventh, eighth, and ninth grade, respectively. There were no significant effects of the two-year, empowerment-based health-promotion school intervention on changes in the accelerometer-measured MVPA and SED, or the self-reported ET frequency and duration, among the adolescents. Overall, the intervention was unsuccessful at promoting PA and reducing SED. Several possible explanations for the intervention's lack of effects are discussed.

Tracking of Pedometer-Determined Physical Activity: A 16-Year Follow-Up Study.

BACKGROUND: The aims of this study were to explore the effect of time and long-termed tracking on pedometer-determined physical activity (PA) from early adolescent to the 30s. METHODS: PA was measured with pedometers [Yamax™ (SW-200)] during 2000 (time 1), 2003 (time 2), 2005 (time 3), 2010 (time 4), and 2016 (time 5). Anthropometric data were collected during time 1. Data from 59 participants (n = 32 males) were analyzed from early adolescent (time 1) to the 30s (time 5). RESULTS: There was an effect of time for males (P = .005, η2 = .76) and females (P = .002, η2 = .50) where steps per day decreased. Males steps per day tracked between time 1 and time 2 (r = .41, P = .021), time 1 and time 3 (r = .38, P = .03), time 3 and time 4 (r = .42, P = .015), and time 4 and time 5 (r = .50, P = .003). Females steps per day tracked between time 4 and time 5 (r = .39, P = .04). Males took more steps per day than females during time 1 (P = .018), whereas females took more steps per day during time 2 (P = .043) and time 3 (P = .03). CONCLUSION: There was a significant effect of time, where steps per day decreased between the 5 times of measurement. Steps per day tracked low to moderate in the short time span, yet tracked nonsignificantly from early adolescent to the 30s.

Levels of physical activity during physical education lessons in Sweden.

AIM: The aim of this study was to measure the percentage of sedentary light and moderate-to-vigorous physical activity (%MVPA) provided by physical education (PE) lessons for Swedish second, fifth and eighth grade students, aged eight, 11 and 14. METHODS: We observed 39 PE lessons and divided them into seven lesson categories: ball play, ball games, dance, fitness, playing games, orienteering and gymnastics. Physical activity (PA) during PE was estimated using accelerometers and the height and weight of the children were measured. RESULTS: We studied 149 children: 63 in the second grade, 66 in the fifth grade and 19 in the eighth grade. On average, 25% of the PE lessons were spent in MVPA and the mean %MVPA varied with the lesson content, with fitness, orienteering and playing games being the most intense. The highest %MVPA was in the fitness category, providing 33% (8-62%) for girls and 37% (7-72%) for boys. With the exception of the second grade, no significant gender differences in %MVPA were seen. CONCLUSION: The content of Swedish PE lessons affected the %MVPA in all age groups. In some content, individuals reached two-thirds of their daily PA recommendations, highlighting the potential that PE contributes to public health goals.

Accelerometer-measured physical activity among adolescents in a multicultural area characterized by low socioeconomic status.

PURPOSE: The aim of this cross-sectional study was to describe and analyze accelerometer-measured sedentary time and physical activity (PA) among adolescents in a multicultural area characterized by low socioeconomic status (SES). METHOD: Seventh-graders (n=114 (girls n=66), mean age: 12.8±0.5 y) were recruited from three schools in a multicultural area of the city of Gothenburg, Sweden. Sedentary time and PA were measured with ActiGraph™ accelerometers. RESULT: Of total wear-time, 70 (±6)% was sedentary, with girls being more sedentary than boys. Girls had less light PA (LPA) and moderate-to-vigorous PA (MVPA) than boys. Similar patterns were shown during in-school and out-of-school hours. During wear-time, 53% had a mean of ≥60 min of MVPA per day, but only 6% of the girls and 24% of the boys were sufficiently physically active every day. Girls had more sedentary bouts of ≥10 min and fewer MVPA bouts of ≥5 min per day than boys. Those who participated in organized sports spent a mean of 15 more minutes of MVPA per day compared to those who did not. No association was observed between body mass index (BMI) and sedentary time and PA. CONCLUSION: Only a few adolescents from a Swedish multicultural area characterized by low SES met the PA recommendations every day, and girls were more sedentary and less physically active than boys. Adolescents involved in organized sports had more of MVPA per day than their non-involved peers. Sedentary time and PA were not related to BMI.

Compulsory School In- and Outdoors-Implications for School Children's Physical Activity and Health during One Academic Year.

Regulated school days entail less free-living physical activity (PA) and outdoor stay, which may jeopardize the opportunities for cohesive moderate-to-vigorous physical activity (MVPA) and, by extension, children's health. The role of outdoor stay during school time for pupils' free-living PA vs. physical education (PE) and indoor stay was studied during one academic year in 196 pupils aged 7-14 years at four schools in mid-southern Sweden during five consecutive days each in September, March, and May. Actigraph GT3X+ Activity monitors were used. Predictors for PA during school stay were expressed as mean daily accelerometer counts and were measured per season, day, grade, gender, weather, and time outdoors. Overall, free-living PA outdoors generated the highest mean accelerometer counts for moderate and vigorous PA. Outdoor PA and PE, representing 23.7% of the total school time contributed to 50.4% of total mean accelerometer counts, and were the greatest contributors to moderate and vigorous PA. Age and weather impacted PA, with less PA in inclement weather and among older pupils. More time outdoors, at all seasons, would favorably increase school children's chances of reaching recommended levels of PA.

Physical Activity, Blood Glucose and C-Peptide in Healthy School-Children, a Longitudinal Study.

AIM: To further elucidate the relationship between physical activity and several risk factors for development of diabetes (glucose, C-peptide and obesity) over time. METHODS: A prospective longitudinal study where physical activity was measured on 199 children from Kalmar and Linköping at age 8, and the same 107 children from Linköping again at age 12. Anthropometric data was collected and blood was analyzed for C-peptide and f-glucose. The children in the study were representative for the general Swedish child population, and on an average lean. RESULTS: High physical activity was related to lower C-peptide at age 8 and 12. This correlation was especially pronounced in boys, who also were more physically active than girls at both time points. The association seen at 8 years of age was similar at age 12 in most children. Children with higher BMI Z-Score had a higher fasting C-peptide (age 12) but linear regression showed that children with more steps per day were less likely to have a higher fasting C-peptide irrespective of BMI. Longitudinal follow-up showed that a decrease in physical activity increased insulin resistance and ß-cell load. CONCLUSIONS: Already in young children, physical activity improves insulin sensitivity and decreases the need of C-peptide over time. This seems to become even more pronounced with increasing age when children are followed longitudinally. Low physical activity increases the load on insulin producing ß-cells, might increase the risk for both type 1- and 2 diabetes.

[Correlation between sedentary behavior and illness varies with the method of measurement]. / Samband mellan stillasittande och ohälsa varierar med mätmetod - Vuxnas risk för insjuknande och död i hjärt-kärlsjukdomar och cancer samt dödlighet av alla orsaker vid inaktivitet.

The objective of this study was to overview high-qualitative systematic reviews to synthesize the evidence for associations between sedentary behavior and health outcomes in adults. There is evidence for a cross-sectional association between accelerometer measured sedentary time and poorer insulin sensitivity, and an association between sedentary breaks and BMI/waist circumference and triglycerides. Based on intervention studies (only randomized cross-over), there is evidence for an association between prolonged sitting and some markers for poorer cardiovascular health, but it is unclear whether this may be generalized to adults in general. There is also evidence to support an association between self-reported sedentary behavior (e.g., screen-time and total sitting time) and cardiovascular disease incidence and death, cancer incidence and death, and all-cause mortality. The inconsistent use of sedentary measures suggests, however, that caution is required when interpreting the results.

Physical self-esteem and personality traits in Swedish physically inactive female high school students: an intervention study.

BACKGROUND: Physical activity provides fundamental health benefits and plays a positive role in physical well-being. The aim of this present study was to investigate whether a 6-month physical activity program could influence physical self-esteem and frequency of physical activity in physically inactive female high school students in short- and long-term periods and whether personality traits were related to physical activity behaviour and compliance with the program. METHODS: The study was a cluster-randomised controlled intervention study including 104 physically inactive female high school students aged 16-19 years, 60 females in an intervention group and 44 females in a control group. The intervention group exercised at sport centres at least once per week during a 6-month period. Questionnaires were used for evaluation. RESULTS: At a 6-month follow up, the intervention group improved physical self-perception in all subdomains and significantly improved physical condition, physical self-worth and self-related health compared to the control group. At 1-year follow up, 25 females out of 53 females were still physically active, and all ratings remained almost the same as at the 6-month follow up. There were no particular personality traits that were dominant in the groups. CONCLUSION: A 6-month physical activity program can positively influence physical self-esteem and the frequency of physical activity, both from a short- and long-term perspective.

[Weak evidence concerning sedentary lifestyle and its association with cardio-metabolic illness among young people. "Junk food" and late evenings in front of the screen part of a complex connection]. / Klena bevis för att stilla-sittande ger kardiometabol ohälsa hos unga - ¼Skräpmat« och sena kvällar framför skärmen del i komplext samband.

During recent decades there has been a rapidly growing interest in youths' sedentary behaviour and its association with cardio-metabolic health. Currently there is little-to-no evidence for a cross-sectional and longitudinal association between volume and pattern (bouts and breaks) of objectively measured sedentary behavior and body weight in youth. Likewise, there is little-to-no evidence for a cross-sectional association between volume and pattern of objectively measured sedentary behavior and other markers for cardio-metabolic risk in youth. However, there is sufficient evidence for a cross-sectional and longitudinal association between screen-time and body weight and blood pressure and blood lipids. Furthermore, there is evidence for a cross-sectional association between youths' screen-time and clustered metabolic risk and insulin resistance. Overall, the level of evidence was low and, therefore, caution is required when interpreting the results.

Physical activity decreased by a quarter in the 11- to 12-year-old Swedish boys between 2000 and 2013 but was stable in girls: a smartphone effect?

AIM: This study explored physical activity, body mass index (BMI) and overweight and obesity from 2000 to 2013 using a convenience sample of second- and fifth-grade Swedish schoolchildren aged 8-9 years and 11-12 years, respectively. METHODS: We examined cross-sectional cohorts of 126 second-grade children in 2000, 84 in 2006 and 44 in 2013 and 105 fifth-grade children in 2000 and 38 in 2013. No fifth graders were available in 2006. Physical activity data were collected based on pedometer readings over four consecutive weekdays, and height and weight were measured. Identical instruments and procedures were used in all three years. RESULTS: There was an increase in physical activity in second-grade girls from 2000 to 2006 (p < 0.01), which then stabilised between 2006 and 2013, but second-grade boys and fifth-grade girls were stable throughout the study period. Fifth-grade boys decreased significantly (24%) from 16 670 to 12 704 steps per day (p < 0.01) from 2000 to 2013. Mean BMI scores remained stable over time. CONCLUSION: Time trends in physical activity differed between boys and girls. Second-grade boys and fifth-grade girls were stable throughout, whereas second-grade girls increased from 2000 to 2006 before stabilising. Fifth-grade boys showed a significant 24% reduction from 2000 to 2013. Changes in recess and leisure time habits, such as smartphone use, may have influenced the result.

Reduction in pedometer-determined physical activity in the adult Danish population from 2007 to 2012.

AIMS: To examine the development in pedometer-determined physical activity from 2007-2008 to 2011-2012 in the adult Danish population. METHODS: The study population comprised two random samples of 18-75-year-old individuals who took part in cross-sectional studies in 2007-2008 (n=224) and 2011-2012 (n=1515). Pedometer data (sealed Yamax SW 200) were obtained for seven consecutive days. Data for 1624 participants (48.2% men) were included in the analysis. An overall step-defined activity level was examined based on a graduated step index (sedentary, low active, somewhat active, active, highly active). The pedometer-determined outcomes were analysed using regression models. RESULTS: A borderline significant decline (p=0.077) from 8788 to 8341 steps/day (-446 (95% confidence intervals -50, 943)) was found between 2007-2008 and 2011-2012. Furthermore, a 23.7% (95% confidence intervals -41.7%, -0.1%) lower overall step-defined activity level was observed in 2011-2012 compared to 2007-2008. These changes were primarily due to a reduced level of activity among women. The proportion of individuals taking ⩾10,000 steps/day decreased non-significantly from 34.8% to 29.3%, whereas the proportion taking <5000 steps/day did not differ between survey periods. CONCLUSIONS: This nationally representative survey suggests an overall reduction in the physical activity level among Danish adults. The reduction was due to a shift in the population distribution from higher to lower levels of activity. If this shift is true, it is worrying from a public health perspective. Our study result needs, however, to be confirmed by other population studies.

Physical self-esteem--a ten-year follow-up study from early adolescence to early adulthood.

INTRODUCTION: One variable that has been consistently associated with adolescents' physical activity is perceived activity competence. Perceived physical (or sport) competence is considered a sub-domain to the physical self-esteem or self-worth (i.e., a person's valuation of what is good and worthy in their self-description). OBJECTIVE: This study aimed to describe levels of and inter-correlations among physical self-esteem, physical activity, and body mass index in a longitudinal design spanning adolescence to early adulthood. MATERIALS AND METHODS: At mean ages of 12.7, 15.7, 17.7 and 22.7 years, we measured perceived physical self-esteem in 39 (22 boys) Swedish adolescents. Physical activity (steps/day) for four consecutive schooldays, height, and weight were also measured. RESULTS: No significant difference between the four time points for any variable of perceived physical self-esteem was seen, neither in boys nor girls. In general, all physical self-variables revealed non-linear trajectories across time, where the general trend was an increase during the younger ages followed by a decrease during older ages. At ages 12 and 15 years in boys and girls physical condition and physical strength as well as body attractiveness and physical strength, respectively, had the strongest correlations to physical self-esteem. At age 17 and 22 years sports competence had the strongest correlation to self-esteem in girls, while body attractiveness and physical strength had the strongest correlation to self-esteem in boys. CONCLUSION: An overall stability in physical self-esteem was found. However the impact of a sub-domain upon physical self-esteem vary during adolescence and early adulthood. Such information may be useful when creating physical activity programs that support and develop physical self-esteem.

A repeated measurement study investigating the impact of school outdoor environment upon physical activity across ages and seasons in Swedish second, fifth and eighth graders.

BACKGROUND: School children are confined to and exposed to outdoor environment that happens to be at their disposal during compulsory school time. The health-promoting potential of outdoor environment, and the use of it, is therefore important. We have studied the impact of school outdoor environment in terms of playground features, space, topography and vegetation upon the patterns of moderate to vigorous physical activity (MVPA) across ages and seasons in Swedish pupils at compulsory school. METHODS: Four schools in the Middle and Southern parts of Sweden, with outdoor environments differing in playground features, space, topography and vegetation were analyzed during one school year. A sample of 196 children was drawn from eligible pupils in grades 2, 5 and 8, aged 7-14 years. PA was monitored with time-stamped Actigraph accelerometers GT3X+, measuring different intensity levels during outdoor time. Maps were used to mark places where the children stayed and what they did during outdoor time. RESULTS: Mean MVPA during outdoor stay was 39 minutes for the entire school year, time in MVPA correlated positively with outdoor time, as did MVPA with used outdoor play area (p < 0.001). Outdoor MVPA declined with age, boys accumulated more MVPA than girls at all ages (p < 0.001). Ball play areas increased MVPA in 5th graders in September and May (p < 0.001). Overall, ball play areas increased 5th graders' relative MVPA, and helped maintaining it with increasing age in boys but not in girls, whereas woodland stimulated and contributed to maintaining girls' MVPA with increasing age. Outdoor temperature significantly impacted (p < 0.01) MVPA throughout all seasons. CONCLUSION: We conclude that school outdoor environment design and outdoor play time impact physical activity on a daily basis and may contribute to increasing girls' physical activity and moderate the sharp decline in physical activity by age. The school outdoor environment may thus be a potential health promoter during school time.