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Providing individual- and population-level data on child physical fitness is a crucial public health and education priority, however, few national fitness monitoring, or surveillance systems are currently in practice globally. The FitBack network includes experts from diverse backgrounds with a common interest to improving the accessibility of physical fitness monitoring and surveillance amongst school-aged children. This paper details findings of the FitBack network; descriptions of eight national or regional European physical fitness monitoring and surveillance systems, and experience-based ten-step guidelines for establishing one’s own system. Fitness monitoring and surveillance systems can successfully be implemented within school-settings, designed to meet the specific needs of a given region, and inform public health policies to reduce future disease burden. Monitoring systems connect to school-settings by teaching and advocating for physical literacy - a key component to maintaining a lifelong active, healthy lifestyle.

BackgroundAn overall healthy lifestyle may mitigate the risk of all-cause and cardiovascular disease (CVD) mortality despite the inherited risk for CVD. We assessed if similar phenomenon is observed independently with physical activity (PA).MethodsIn a prospective older Finnish Twin Cohort, genetic liability for coronary heart disease, systolic and diastolic blood pressure was estimated with polygenic risk scores (PRSs) derived from the Pan UK Biobank (N≈400,000) and >1,000,000 genetic variants, and leisure-time PA longitudinally with validated and structured questionnaires three times during 1975–1990 among 4,897 participants aged 33–60-years (54.3% women). Interactions of PRSs and PA with mortality and the independent main effects of different PA metrics with mortality were evaluated with Cox proportional hazards models. A co-twin control design with 180 monozygotic twin pairs discordant for physical activity was used for causal inference.ResultsDuring the 17.4-y (mean) follow-up (85,136 person-years), 1,195 participants died with 389 CVD deaths. Although the favorable associations of an overall healthy lifestyle with mortality risk reduction replicated in the cohort, no interactions or significant independent main effects were observed with any of the assessed PA metrics. Adherence to World Health Organizations PA guidelines or vigorous PA during the 15-year observational period did not decrease mortality in more active twins compared to their less active identical twin brother or sister. The findings did not vary with genetic CVD risk.ConclusionsNo evidence was found that PA mitigates inherited CVD risk or is causally associated with mortality challenging some of our current understanding.

BackgroundPhysical activity (PA), aerobic fitness, and cardiometabolic diseases (CMD) are highly heritable multifactorial phenotypes. Shared genetic factors may underlie the associations between higher levels of PA and better aerobic fitness and a lower risk for cardiometabolic CMDs. Our aim was first to validate PA genotype against self-reported leisure-time PA (LTPA) and second to study how PA genotype associates with aerobic fitness and CMD risk factors. Finally, we investigated if PA genotype predicts CMD endpoints. We expected that these analyses would provide evidence for pleiotropic effects (same gene variants explaining both phenotypes) of PA and CMDs.Methods and findingsPolygenic risk score (PRS) for PA was constructed in the Trøndelag Health Study (N=47,148) using UK Biobank single nucleotide polymorphism-specific weights (N=400,124). The results showed that genotypes predisposing to higher PA were associated with greater self-reported PA (Beta [B]=0.282 MET-h·wk-1per SD of PRS for PA, 95% confidence interval [CI]=0.211, 0.354) but not with aerobic fitness. These genotypes were also associated with healthier profile in CMD risk factors (waist circumference [B=-0.003 cm, 95% CI=-0.004, -0.002], body mass index [B=-0.002 kg·(m2)-1, 95% CI=-0.004, -0.001], high-density lipoprotein cholesterol [B=0.004 mmol·L-1, 95% CI=0.002, 0.006]) and lower incidence of hypertensive diseases (HR=0.97, 95% CI=0.951, 0.990), stroke (HR=0.94, 95% CI=0.903, 0.978) and type 2 diabetes (HR=0.94, 95% CI=0.902, 0.970). When accounting for self-reported PA, the associations between PA genotypes and CMD risk factors remained statistically significant.ConclusionsGenotypes predisposing to higher PA were associated with higher amount of PA. However, in general the predictive value of the PRS for PA in predicting self-reported PA was low, possibly because of the acknowledged inconsistencies in assessing PA in cohort studies. Genotypes predisposing to higher PA were also associated with better cardiometabolic health and lower incidence of CMDs, and the observed associations were independent of self-reported PA. These results support earlier findings suggesting small pleiotropic effects between PA and CMDs and provide new evidence about associations with polygenic inheritance of PA and intermediate CMD risk factors. The observed association were however small, and results do not suggest clinical relevance in health promotion.

Purpose The purpose of this study was to examine whether physical activity, fitness and motor skills have indirect association with math performance via cognitive outcomes and if so, through which aspects of cognition? Methods This study comprised 311 6th–9th grade adolescents (12–17y [M age=14.0y], 59% girls) from seven schools throughout Finland in 2015. Math performance was measured via a teacher-rated math achievement and the Basic Arithmetic test. Cognitive functions were measured by broad cognitive test battery. Physical activity was assessed with a self-reported questionnaire and a hip-worn accelerometer. Aerobic fitness was estimated using a maximal 20-m shuttle run test, muscular fitness with curl-up and push-up tests, and motor skills with a 5-leaps test and a throwing-catching combination test. Structural equation modeling was applied to examine the associations. Results In both boys and girls, motor skills had a positive indirect association with math outcomes through visuospatial working memory. Among girls, muscular fitness had a positive indirect association with math outcomes through visuospatial working memory. Aerobic fitness was positively associated with math achievement, but the indirect path via cognition was not observed. Self-reported physical activity had a borderline indirect positive association with math outcomes through visuospatial working memory. Accelerometer-based physical activity did not correlate with math performance. Conclusion Motor skills and muscular fitness had indirect, positive associations with math performance, mediated by visuospatial working memory. The results give support to the viewpoints that the connections between motor skills, fitness and physical activity to academic skills are mediated via specific cognitive skills. peerReviewed

The decline in adolescents’ physical fitness (PF) in recent decades has raised concerns about current population’s possible future challenges with health and physical functional capacity. This study explored the associations between body composition, physical activity, maturation, and PF development in adolescents. Furthermore, PF development of adolescents with low initial PF was assessed. A 2‐year observational study was conducted between spring 2013 and 2015. Nine comprehensive schools and their 10‐ to 13‐year‐old students were invited to participate in the study (1778), and a total of 971 students (54.6%) agreed. Cardiorespiratory fitness (20‐metre shuttle run), muscular fitness (push‐ups), fundamental movement skills (5‐leaps test), body composition (bioelectrical impedance analysis), moderate‐to‐vigorous physical activity (accelerometer) and pubertal status (self‐assessment questionnaire) were measured at 1‐year intervals. Latent growth curve modeling (LGM) was used to study PF development over time. Change in fat mass had the strongest and most coherent associations with PF development during adolescence. Fat‐free mass, moderate‐to‐vigorous physical activity and pubertal status were associated with PF development, although not systematically. Subgroup analyses showed that PF development in the low fitness group followed a similar pattern as the whole population. However, their PF remained significantly lower throughout the 2‐year period. The findings suggest that fat accumulation is an essential detrimental factor for PF development during adolescence. Actions to prevent excessive fat accumulation might help to prevent future declines in functional capacity. Indications that low fitness levels sustain during adolescence highlight the relevance of detecting these individuals and providing interventions already before adolescence. peerReviewed

Objectives This study aimed to investigate cross-lagged associations of leaping skill and throwing–catching skills with objectively measured moderate-to-vigorous physical activity (MVPA) and sedentary time (ST) during school transition from upper primary (Grade 6) to lower secondary school (Grade 7). Design This study is a one-year prospective follow-up study within Finnish school settings. Students’ MVPA, ST, leaping skill and throwing–catching skills were measured at Grade 6 and subsequently at Grade 7. Methods A sample of 336 students (163 girls, 173 boys; M age = 12.0 years, SD = 0.4 at Grade 6 participated in the study. Students’ MVPA and ST were measured objectively by hip-worn accelerometers. Leaping skill was measured by 5-leaps test. Throwing and catching skills were measured by throwing–catching combination test. Cross-lagged structural equation modeling was conducted to evaluate the associations between MVPA, ST, leaping skill, and throwing–catching skills at Grade 6 and Grade 7. Results Results demonstrated three significant cross-lagged associations among girls: (1) leaping skill measured at Grade 6 was negatively associated with ST at Grade 7; (2) objectively measured MVPA at Grade 6 associated positively with leaping skill at Grade 7; and (3) throwing–catching skills measured at Grade 6 associated positively with leaping skill measured at Grade 7. There were no statistically significant cross-lagged associations between the study variables for the sample of boys. Conclusions The results of this study indicated that supporting opportunities for girls’ engagement in both MVPA and leaping skill development activities during their primary school education is strongly recommended.

Supplemental digital content is available in the text., Purpose This study aimed to examine both independent and dependent longitudinal associations of physical fitness (PF) components with academic achievement. Methods A total of 954 fourth to seventh graders (9–15 yr [Mage = 12.5 yr], 52% girls) from nine schools throughout Finland participated in a 2-yr follow-up study. Register-based academic achievement scores (grade point average [GPA]) and PF were assessed in the spring of 2013–2015. Aerobic fitness was measured with a maximal 20-m shuttle run test, muscular fitness with curl-up and push-up tests, and motor skills with a 5-leaps test and a throwing–catching combination test. Structural equation modeling was applied to examine the longitudinal associations adjusting for age, gender, pubertal stage, body fat percentage, learning difficulties, and mother’s education. Results The changes in aerobic and muscular fitness were positively associated with the changes in GPA (B = 0.27, 99% confidence interval [CI] = 0.06–0.48; B = 0.36, 99% CI = 0.11–0.63, respectively), whereas the changes in motor skills were not associated with the changes in GPA. Better motor skills in year 2 predicted better GPA a year later (B = 0.06, 99% CI = 0.00–0.11; B = 0.06, 99% CI = 0.01–0.11), whereas aerobic and muscular fitness did not predict GPA. GPA in year 1 predicted both aerobic (B = 0.08, 99% CI = 0.01–0.15) and muscular (B = 0.08, 99% CI = 0.02–0.15) fitness, and motor skills (B = 0.08, 99% CI = 0.02–0.15) a year later. Conclusion The changes in both aerobic and muscular fitness were positively associated with the changes in academic achievement during adolescence, whereas the changes in motor skills had only borderline significant association. However, better motor skills, although not systematically, independently predicted better academic achievement 1 yr later, whereas aerobic or muscular fitness did not. Better academic achievement predicted better motor skills, aerobic fitness, and muscular fitness. Developmental changes in adolescence may induce parallel and simultaneous changes in academic achievement and PF.

The aim of this study was to examine and quantify the cross-sectional associations of body composition (BC), physical activity (PA) and sedentary time (ST) with physical fitness (PF) in children and adolescents. A sample of 594 Finnish students (56% girls), aged 9-15 (12.4 ± 1.3 years) were selected for a study performed in 2013. The measurements of the Move! monitoring system for physical functional capacity were used to measure cardiorespiratory and musculoskeletal fitness and fundamental movement skills. Moderate-to-vigorous PA (MVPA) and ST were measured objectively with an accelerometer and BC by a bioelectrical impedance analysis. Fat mass index (FMI) and fat-free mass index (FFMI) were calculated to represent height-adjusted BC. Associations were explored with a linear regression model. In general, FMI had statistically significant negative associations, while FFMI and MVPA had positive associations with PF. No statistically significant associations were observed between ST and PF. In general, FMI had the strongest association with PF, although some variation occurred with sex and PF component. However, associations were practically relevant only in 20-m shuttle run, push-up, curl-up and 5-leaps test. For example, approximately 5 kg increase in fat mass in 155 cm tall children was estimated to correspond to 8 laps in 20-m shuttle run. Similar increase in fat-free mass corresponded to +4 and +6 laps, and 10 min increase in daily MVPA +3 and +2 laps in 20-m shuttle run, in boys and girls, respectively. Understanding these associations is necessary when interpreting children's PF and designing interventions.

Summary Small-scale turbulence is a key factor in increasing encounter rates but also dispersing prey patches of planktonic organisms and can thus contribute to their distribution. Our hypotheses were that turbulence can (i) disturb the vertical refuge use of fourth instar Chaoborus flavicans larvae and (ii) also disperse them horizontally. Both were tested experimentally, across a gradient of turbulence. The vertical experiments were conducted in 46-L cylinders, providing the larvae a vertical refuge by darkening the bottom layer. The horizontal experiments were conducted in a 200-L aquarium, providing them a horizontal refuge by darkening one end of the aquarium. With both set-ups, two light treatments were tested: uniform darkness as a control and the bottom layer of the cylinder or either end of the aquarium darkened to provide a refuge. In addition to non-turbulent treatment, five different root-mean-square (RMS) velocities were generated, ranging from 0.6 to 10.2 cm s−1 in the vertical and to 10.9 cm s−1 in the horizontal experiment. Increasing turbulence had a significant effect on the distribution of C. flavicans larvae in both vertical and horizontal directions and increased the proportion of larvae in the non-preferred illuminated environment. In the vertical direction, the proportion of larvae in the refuge decreased linearly with increasing turbulence, showing a decline from 84% under calm conditions to 61% at the highest RMS velocity (10.2 cm s−1). The effect of turbulence was more prominent in the horizontal direction; without turbulence, 86% of the larvae occupied the refuge, but the proportion declined to 32% at 5.4 cm s−1 RMS velocity. In experiments with uniform darkness, the distribution of chaoborids was not affected by turbulence either in the vertical or in the horizontal direction. Our results indicate that turbulence has substantial effects on refuge use and distribution of C. flavicans larvae. Increasing turbulence can greatly diminish the ability of prey species to use their vertical refuges. Once away from their vertical refuge, chaoborids are highly vulnerable to horizontal dispersion, thus upsetting their horizontal escape behaviour. Small-scale turbulence is therefore likely to have considerable effects on food-web dynamics in lakes.

Turbulence and turbidity are thought to independently affect the foraging success of fish, but little is known about their interactive effects on the feeding of fish larger than a few centimetres. We experimentally tested for this interaction on the feeding of planktivorous perch (Perca fluviatilis). There was an interactive effect of root mean square (RMS) velocity (0, 1.3, 2.7, 5.5, and 18.3 cm·s−1) and turbidity (0, 30, and 60 nephelometric turbidity units; NTU) on perch feeding on phantom midge larvae (Chaoborus flavicans). In the 0 and 60 NTU conditions, there was no significant change in the feeding efficiency of perch. However, at 30 NTU, increasing turbulence enhanced perch feeding by increasing encounter rates and disabling the prey escape response. The proportion of encountered Chaoborus larvae that were consumed showed a linear decline with increasing turbulence under clear and 30 NTU conditions and a dome-shaped response under 60 NTU. The results indicate that turbulence has a strong effect on the post-encounter stages of the foraging cycle.

The effects of the emergent macrophyte Phragmites australis on water turbulence, bottom shear velocity and water turbidity were experimentally studied with the stem densities 0 stems/m 2 -100 stems/m 2 and using organic-rich sediment. It is found that the maximum root-mean-square (rms) velocity and shear velocity decrease linearly with increasing stem density. By affecting the height of peak turbulence values, emergent plants can thus lower the frequency of sediment erosion events. Additionally, the slope of the rms turbulence increment decreases with increasing stem density. Thus, also the duration of strong turbulence is affected by the density of emergent macrophytes. The critical shear velocity for sediment resuspension is 0.0035 m/s-0.0055 m/s and not affected by the stem density. In the absence of macrophytes, water flow causes a 6.3-fold increment in turbidity, but with macrophytes turbidity values remain lower. The experiments suggest that even relatively low densities of Phragmites can have substantial effects on water turbulence and consequently on water quality.