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The Danish Christmas Seal Homes offer a 10-week residential stay for socially vulnerable children. We aimed to examine the effects on body composition and cardiometabolic fitness variables of the standard program (SG) and whether substituting physical activity sessions with sessions from a football-based health education program is beneficial for the participants ("11 for Health"; SG+). Three hundred and nine children participated in SG (12.4 [1.6] y) and 305 in SG+ (12.4 [1.4] y). Fat percentage was lowered by 6% for females (from 37% to 31%) and 8% for males (from 36% to 28%), with no between-group differences. We observed improvements in systolic and diastolic blood pressure (3 and 5 mm Hg, respectively), resting heart rate (10 beats/min), aerobic fitness, jump performance, and relative muscle mass with no between-group differences. Furthermore, there were between-group differences in insulin levels for females (1.7 pmol/L; 95% CI, 0.3 to 3.0) and postural balance for males (1.0 s; 95% CI, 0.0 to 2.0), both in favor of SG+, and covered distance in the Andersen test for females (26 m; 95% CI, 3 to 49) in favor of SG. In conclusion, a 10-week stay at the Danish Christmas Seal Home resulted in clinically relevant improvement in fat percentage and cardiometabolic fitness in socially vulnerable children, regardless of the program type.

The Danish healthcare system is currently undergoing a transformation towards increased use of virtual healthcare services. In this review, we propose a structured risk-stratified model to delineate the differences between homecare, homemonitoring, and hospital-at-home, while discussing their current status and addressing barriers hindering the widespread adoption and scaling of home-based care incl. technological limitations, regulatory complexities, and cultural considerations. We advocate for establishing a national central support function to expedite the shift towards home-based care., (Published under Open Access CC-BY-NC-BD 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/.)

Background/objectives: The aim of this study was to evaluate the effects of lifelong team handball/football training on regional bone health and body composition in elderly women., Methods: Seventeen elderly women team handball/football players (65.9 ± 5.7 years) and twenty-one untrained age-matched women (controls) (67.7 ± 5.1 years) participated. Whole-body and regional dual-energy X-ray absorptiometry scans of arms, legs, and lower spine (L1-L4) were performed., Results: We observed 8% and 9% higher bone mineral density (BMD) and bone mineral content (BMC), respectively, at the whole-body level and in the legs and 11.5% higher BMC in the legs in team handball/football players compared to untrained age-matched controls ( p < 0.05). Higher total and leg lean body mass ( p < 0.05), along with lower total body fat percentage (p < 0.05) and higher T- and Z-scores, markers of fragility risk fracture (0.294 ± 1.461 vs. -0.538 ± 1.031; 1.447 ± 1.278 vs. 0.724 ± 0.823, respectively), were also found in team handball/football players compared to controls ( p < 0.05). No significant differences in nutritional habits were observed between groups., Conclusions: Our study suggest that the beneficial effects of lifetime handball/football practice on bone preservation in elderly women occur independently from nutritional intake, which emphasize the potential role of team sports in osteoporosis prevention. Future studies should focus on the cofounding factors and causative mechanisms mediated by team sport practice in osteoporosis prevention.

Introduction: The purpose of the present study was to investigate the impact of the FIT FIRST FOR ALL school-based physical activity program on health-related physical fitness in Faroese schoolchildren. The program aimed to add three weekly sessions of organized high-intensity physical activity to the standard weekly physical education sessions for all pupils across the entire school., Methods: A non-randomized controlled design was used to evaluate the effects of the program. Two schools participated, including one intervention school (INT; n  =179) and one control school (CON; n  =181), with pupils aged 7-16 years (grades 1-9). The FIT FIRST FOR ALL program consisted of three weekly 40-minute sessions of age-adjusted high-intensity physical activity over 10 weeks for the INT school, while the CON school continued their normal school program. Pre- and post-intervention assessments included cardiorespiratory fitness (Yo-Yo IR1C test), agility (Arrowhead Agility test), postural balance (Stork Stand), standing long jump performance, body composition, blood pressure, and resting heart rate., Results: A significant time × group effect ( p  < 0.001) was observed for cardiorespiratory fitness, which increased by 31% [23;39] in INT ( p  < 0.001) and remained unaltered in CON (7% [-2;16], p  = 0.13). In addition, a time × group effect ( p  < 0.001) was observed for agility, which improved by 2.1% [1.0;3.2] in INT ( p  < 0.001) and regressed by 3.3% [2.3;4.4] in CON ( p  < 0.001). No significant between-group effects were found for standing long jump and balance. A time × group effect ( p  < 0.001) was observed for changes in total muscle mass, which increased by 1.4 kg [1.2;1.5] in INT ( p  < 0.001) and by 0.4 kg [0.3;0.6] in CON ( p  < 0.05). Furthermore, a time × group effect ( p  < 0.001) was observed for total fat percentage, which decreased by -2.3% [-2.8;-1.9] in INT ( p  < 0.001) and remained unchanged in CON (-0.3% [-0.7;0.1], p  = 0.16). No significant time × group effects were found for blood pressure and resting heart rate., Discussion: The FIT FIRST FOR ALL program significantly improved cardiorespiratory fitness and agility, and it led to favorable changes in body composition in the intervention school. These findings suggest that the program is highly effective in enhancing physical fitness and health status across all investigated age groups when implemented at a school-wide level., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Olsen, Sjúrðarson, Danielsen, Krustrup, Larsen, Skoradal and Mohr.)

Greenhouse cultivation has been expanding rapidly in recent years, yet little knowledge exists on its global extent and expansion. Using commercial and freely available satellite data combined with artificial intelligence techniques, we present a global assessment of greenhouse cultivation coverage and map 1.3 million hectares of greenhouse infrastructures in 2019, a much larger extent than previously estimated. Our analysis includes both large (61%) and small-scale (39%) greenhouse infrastructures. Examining the temporal development of the 65 largest clusters (>1,500 ha), we show a recent upsurge in greenhouse cultivation in the Global South since the 2000s, including a dramatic increase in China, accounting for 60% of the global coverage. We emphasize the potential of greenhouse infrastructures to enhance food security but raise awareness of the uncertain environmental and social implications that may arise from this expansion. We further highlight the gap in spatio-temporal datasets for supporting future research agendas on this critical topic., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Background: The COVID-19 pandemic has posed unprecedented challenges to healthcare systems globally, necessitating innovative care models like hospital-at-home and virtual care programs. The Influenzer telemedicine program aims to deliver hospital-led monitoring and treatment to patients at home. Integrating telemedicine technology with domestic visits provides an alternative to traditional hospitalization, with the aim of easing the burden on healthcare facilities without compromising patient safety. To evaluate the effectiveness of the Influenzer program, a randomized controlled trial is proposed. This study aimed to assess the feasibility of the proposed clinical trial design., Methods: A non-randomized feasibility study was conducted at the Department of Pulmonary and Infectious Diseases at Nordsjaellands Hospital offering a telemedicine-supported early discharge program to patients with lower respiratory tract infections, including COVID-19. The feasibility of trial procedures, including recruitment, adherence, and retention, was analyzed. Also, participants' characteristics and trajectory during the intervention, including telemedicine and domestic services, were assessed., Results: Nineteen patients were enrolled from June 2022 to April 2023 and treated at home. Forty patients were not enrolled as 15 (25%) were non-eligible according to study protocol, 15 (25%) refused to participate and 10 (17%) had not been approached. Subjects treated at home had comparable clinical outcomes to those treated in the acute hospital, no major safety incidences occurred and patients were highly satisfied. Participants demonstrated 99% adherence to planned daily monitoring activities. In total, 63% completed all survey assessments at least partially including baseline, at discharge, and 3 months post-discharge, while 89% participated in a follow-up interview. No participants withdrew their consent., Conclusions: The feasibility study documented that the Influenzer home-hospital program was feasible and well accepted in a Scandinavian setting in terms of no withdrawals and excellent participant adherence to the planned daily monitoring activities. Challenges in the organizational structures including patient recruitment and data collection required resolution prior to our randomized clinical trial. Insights from this feasibility study have led to the improved design of the final Influenzer program evaluation trial., Trial Registration: ClinicalTrials.gov, NCT05087082. Registered on 18 August 2021., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The purpose of the present study was to evaluate the effects of the football-based health education program "11 for Health" on health knowledge and well-being in the setting of a 10-week residential stay in a Danish charity home for socially vulnerable children. Six hundred and fourteen children participated in the study, of which 305 took part in the standard program plus "11 for Health" (SG+: 12.4 ± 1.4 (mean ± SD) years) and 309 took part in the standard program (SG: 12.4 ± 1.6 years). We used a crossover design over two full years. The study examined changes in health knowledge and well-being through questionnaires. Overall health knowledge increased more in SG+ than SG over 10 weeks (6.6 vs. 3.4%, p < 0.05). The overall well-being scores were markedly improved (p < 0.05) by 4.54 ± 7.17 AU in SG+ and 4.51 ± 7.16 AU in SG, with no between-group differences. Specific improvements (p < 0.05) were seen in all well-being subcategories, raising the well-being scores to the national average. In conclusion, a 10-week stay at a Danish charity home, the Christmas Seal Home, markedly affected health knowledge and well-being of socially vulnerable children. When the football-based health education program-11 for Health-was added, there were additional positive effects on health knowledge., (© 2024 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

The effects of lifelong football training on bone health, body composition and physiological demands were evaluated. A total of 20 veteran football players (VPG; 73.4 ± 3.7 years) and 18 untrained age-matched men (CG; 75.6 ± 4.2 years) were enrolled. Whole-body and regional dual-energy X-ray absorptiometry scans of arms, legs, proximal femur and lower spine (L1-L4) were recorded in all participants. We observerd higher bone mineral density (BMD) in the whole-body, arms and femoral regions and higher bone mineral content (BMC) in the legs and lower spine compared to the CG ( p < 0.05), also higher total lean body mass ( p < 0.05) and lower total body fat percentage ( p < 0.05), were found. No differences in food habits were evidenced between the VPG and the CG, as evaluated using 3-day food records. Resting heart rate (RHR), blood pressure (BP) and activity profile during a football match were recorded using a global positioning system only in the VPG. The mean heart rate (HR)of theoretical maximal HR (ThHRmax), and peak of ThHRmax were 83.9 ± 8.6% and 98.6 ± 10.2%, respectively; the mean of total distance covered was 3666 ± 721 m, and the means of accelerations and decelerations were 419 ± 61 and 428 ± 65, respectively. Lifelong participation in football training improves regional BMD and BMC in legs, femur and lumbar spine compared to the CG. A high number of intense actions in term of HR and accelerations and decelerations suggests an elevated energy expenditure that in turn correlates to the healthier body composition observed in the VPG compared to the CG.

Background: The left ventricular assist device (LVAD) is a mechanical circulatory support device for patients with severe heart failure. Microbubbles caused by cavitation in the LVAD can potentially lead to physiological and pump-related complications. The aim of this study is to characterize the vibrational patterns in the LVAD during cavitation., Methods: The LVAD was integrated into an in vitro circuit and mounted with a high-frequency accelerometer. Accelerometry signals were acquired with different relative pump inlet pressures ranging from baseline (+20 mmHg) to -600 mmHg in order to induce cavitation. Microbubbles were monitored with dedicated sensors at the pump inlet and outlet to quantify the degree of cavitation. Acceleration signals were analyzed in the frequency domain to identify changes in the frequency patterns when cavitation occurred., Results: Significant cavitation occurred at the low inlet pressure (-600 mmHg) and was detected in the frequency range between 1800 and 9000 Hz. Minor degrees of cavitation at higher inlet pressures (-300 to -500 mmHg) were detected in the frequency range between 500-700, 1600-1700 Hz, and around 12 000 Hz. The signal power of the dominating frequency ranges was statistically significantly different from baseline signals., Conclusion: Vibrational measurements in the LVAD can be used to detect cavitation. A significant degree of cavitation could be detected in a wide frequency range, while minor cavitation activity could only be detected in more narrow frequency ranges. Continuous vibrational LVAD monitoring can potentially be used to detect cavitation and minimize the damaging effect associated with cavitation., (© 2023 The Authors. Artificial Organs published by International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

Rivers and estuaries are regarded as major pathways of microplastic (MP) transport from terrestrial areas to marine ecosystems. Despite this knowledge on the transport dynamics and fate of MP in freshwater riverine and brackish estuarine waters is limited. Via ex situ settling experiments emulating the Msimbazi River and Estuary in Dar es-Salaam, Tanzania, we demonstrate that flocculation and subsequent settling of positively buoyant MP and fine-grained suspended sediment in riverine and estuarine waters are important for the environmental fate of the plastic particles. Our results show that settling velocities of MP and fine-grained sediment in estuarine water were between five and 21 times larger than in freshwater, explained by the increase in ionic strength that occurs when particles enter saline water. This confirms the concept of increased flocculation and settling of fine-grained particles as they are transported from freshwater to estuarine and marine waters. The implication is that land-based sources of small positively buoyant high-density polyethylene (HDPE) MP transported by rivers will tend to settle and accumulate in estuarine environments and thereby lead to a decrease in the overall load of MPs delivered to the wider marine environment. Thereby our results support the notion of estuaries as MP traps and that flocculation explains the trapping of large quantities of MP debris. Based on these findings we recommend that the interaction of MP with fine-grained sediment should be taken into account when transport models of this pollutant are established., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

This article explores how human development is constrained by collective and personal meaning-making processes. The empirical work of the study is grounded in interviews with children and educational staff at a Danish youth club and concerns children's selection, personalization, and (re)construction of various "TikTok-trends" through the digital media, TikTok. With empirical examples from both the children and the educational staff, the analytical work is anchored in James Mark Baldwin's theoretical conceptualization of persistent imitation. It will be argued that children's persistent imitation is guided by and may diverge from historical and cultural meanings with a twofold attention to the "TikTok-community" and the educational staff. Here, the notion of "inappropriate" imitation, or development, will be unfolded as a resistant meaning construction in the tension field between what is being promoted by the collective and what is imitated by the child. Following this, it will be argued that the social guidance creates developmental ruptures and stability during ontogeny., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: We aimed to investigate the popularity of the "11 for Health program for Europe" for 10-12-year-old Faroese children and the effects on well-being and health knowledge., Methods: We applied a cluster-randomized controlled trial, including a total of 19 school clusters, randomized into intervention schools (IG, n = 12) and control schools (CG, n = 7). A total of 261 children (137 boys and 124 girls) participated. IG completed the 11-week program, consisting of 2 × 45 min weekly sessions with football drills, small-sided games, and health education. CG continued their regular education. Pre- and post-intervention, the participants completed a shortened version of the multidimensional well-being questionnaire KIDSCREEN-27 and a 34-item multiple-choice health knowledge questionnaire., Results: Between-group differences (p < 0.05) were observed in change scores for physical well-being and overall peers and social support in favor of IG compared with CG, as well as for physical well-being in IG girls compared with CG girls. Between-group differences in change score for overall health knowledge (11.8%, p < 0.001, ES: 0.82) were observed in favor of IG, as well as for playing football (8.9%, p = 0.039, ES: 0.24), be active (8.1%, p = 0.017, ES: 0.32), control your weight (18.5%, p < 0.001, ES: 0.52), wash your hands (19.5%, p < 0.001, ES: 0.59), eat a balanced diet (19.3%, p < 0.001, ES: 0.64), get fit (12.1%, p = 0.007, ES: 0.34), and think positive (5.5%, p = 0.039, ES: 0.22). The program was reported as enjoyable with equal moderate-to-high scores for girls (3.68 ± 1.23; ±SD) and boys (3.84 ± 1.17) on a 1-5 Likert Scale., Conclusion: The "11 for Health program for Europe" improved physical well-being, peers, and social support and broad-spectrum health knowledge in 10-12-year-old Faroese schoolchildren and was rated popular., (© 2023 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Purpose: To investigate the effects of the "11 for Health" programme on musculoskeletal fitness., Methods: A total of 108 Danish children aged 10-12 years participated in the study, with 61 children in the intervention group (IG, 25 girls and 36 boys) and 47 children in the control group (CG, 21 girls and 26 boys). Measurements were conducted before and after an 11-week intervention consisting of twice-weekly 45-min football training sessions for IG or continuation of normal Physical Education program for CG. Whole-body dual X-ray absorptiometry was conducted for evaluation of leg and total bone mineral density as well as bone, muscle and fat mass. Standing Long Jump and Stork balance tests were employed to assess musculoskeletal fitness and postural balance., Results: During the 11-week study period, leg bone mineral density as well as leg lean body mass increased more ( p  < 0.05) in the intervention group (IG) compared to the control group (CG) (0.021 ± 0.019 vs 0.014 ± 0.018 g/cm 2 and 0.51 ± 0.46 vs 0.32 ± 0.35 kg, respectively). Moreover, body fat percentage decreased more in IG than in CG (-0.6 ± 0.1 vs 0.1 ± 0.1 %-points, p  < 0.05). No significant between-group differences were found in bone mineral content. Stork balance test performance increased more in IG than in CG (0.5 ± 2.6 vs -1.5 ± 4.4 s, p < 0.05), whereas no between-group differences were found in jump performance., Conclusions: The school-based football programme, 11 for Health, with twice-weekly 45-min training sessions over 11 weeks improves various, but not all evaluated parameters related to musculoskeletal fitness in 10-12-yr-old Danish school children., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors. Published by Elsevier Inc.)

The "11 for Health in Denmark" in-school educational football program has shown to have numerous positive physiological and psychological effects in 10- to 12-year-old schoolchildren. A key part of the successful application of the program, however, has not yet been examined, namely the motivational processes underlying participation and behavioral changes. This study examined such motivational processes (i.e., autonomous motivation, beliefs, and intentions) using the trans-contextual model (TCM) and investigated if the 11 for Health in Denmark program increased intentions to participate in physical activity (PA) outside of school in 10- to 12-year-old schoolchildren. Using a web-based questionnaire, Danish-speaking schoolchildren (N = 276 [boys, 50.4%]; M age  = 10.44, SD = 0.35) from three schools and seven classes completed TCM-based questionnaires at three time-points (weeks 0, 1, and 5) while participating in the 11 for Health in Denmark program. Single-indicator structural equation modeling was performed to examine goodness-of-fit and parameter estimates. A path analysis using maximum likelihood estimation was used to test the direct and indirect effects of the TCM model. The results partly supported a mediation sequence, as we found significant direct effects in eight of 13 motivational variables (β = -0.25-0.83, p < 0.05), indirect effects in one of nine variables (β = 0.15, p < 0.01), but no effects with regard to PA behavior. Findings provide evidence for a motivational link between Danish-speaking schoolchildren's autonomous and controlled motivation from in school to out of school, and may inform future interventions promoting motivation and participation in out of school PA., (© 2022 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Viet Nam is challenged by extensive marine plastic pollution, however, remediation efforts are hampered by undefined sources to the coastal environment. This study surveyed the abundance, type, and source of beached plastic litter at seven beaches along the coast of Nha Trang, Viet Nam. A total of 4754 beached plastic litter items (>2 cm) yielded a mean abundance of 19.8 ± 19.5 items m -2 corresponding to 116 ± 226 g DW m -2 . Our results demonstrate that plastic litter related to fishing and aquaculture constituted at least 62 % of the total by weight and 38 % by number, showing that these two sectors are responsible for a significant part of the plastic pollution along the coast. Hence, we argue that improved management of the fishing and aquaculture sectors could substantially reduce marine plastic pollution along Viet Nam's coast., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Abstract: Madsen, M, Larsen, MN, Cyril, R, Møller, TK, Madsen, EE, Ørntoft, C, Lind, RR, Ryom, K, Christiansen, SR, Wikman, J, Elbe, AM, and Krustrup, P. Well-being, physical fitness, and health profile of 2,203 Danish girls aged 10-12 in relation to leisure-time sports club activity-with special emphasis on the five most popular sports. J Strength Cond Res 36(8): 2283-2290, 2022-This study investigated the relationship between leisure-time sports club activities and well-being as well as physical health parameters in 10-12-year-old Danish girls. Two thousand two hundred three girls took part in the study, which included questionnaires on participation in leisure-time sports clubs, well-being, Yo-Yo intermittent recovery level 1 children's test, long jump, balance tests, body composition, blood pressure (BP), and resting heart rate (RHR). Data were analyzed according to whether the girls participated in leisure-time sport and according to the 5 most frequently reported sports. Girls enrolled in leisure-time sports had higher physical well-being (49.3 ± 8.6 vs. 45.2 ± 8.3), psychological well-being (50.4 ± 9.0 vs. 49.4 ± 9.8), experienced more peer and social support (50.2 ± 10.0 vs. 48.9 ± 10.7), and perceived a more positive school environment (52.5 ± 8.0 vs. 50.5 ± 9.3), as well as showing higher Yo-Yo (+39%), long jump (+10%), and balance performance (+15%) than girls not involved in sport clubs. The girls active in sports clubs had higher relative muscle mass (+5%), lower fat percentage (-11%), body mass index (-5%), RHR (-3.4 b·min -1 ), and diastolic BP (-1.4 mm Hg) compared with girls not involved in sport ( p < 0.05). Girls who played soccer showed higher aerobic fitness compared with inactive girls (+67%), dancers (+39%), swimmers (+38%), and gymnasts (+16%). Gymnasts had a lower fat percentage than inactive girls (-19%), team handballers (-10%), swimmers (-12%), and soccer players (-4%). Girls participating in club-based leisure-time sports showed higher well-being and better fitness and health profiles than girls not involved in any sports club activities. Girls involved in soccer had better aerobic fitness and gymnasts a lower fat percentage., (Copyright © 2020 National Strength and Conditioning Association.)

In this descriptive pilot study, we aim to establish a porcine Staphylococcus aureus skin infection model by subcutaneous injection (s.c.) of the porcine S54F9 S. aureus strain in the groin area. Six pigs were used in the study: Five pigs were injected with S. aureus, inocula ranging from 7 × 10 3 to 5 × 10 7 colony-forming units per kg bodyweight; one pig was injected with saline exclusively. Lesions were recorded up to 6 days postinoculation using clinical evaluation, ultrasound evaluation, microbiology, flow cytometry, and pathology. Inoculation gave rise to lesions ranging from localized skin infection, that is, minute histological changes, intracellular infection, and macroscopic abscess formation with sequestration of soft tissue, to generalized infection and development of disseminated intravascular coagulation necessitating euthanasia only 10 h after inoculation. Ultrasound assessment of maximum width and characteristics was not able to disclose the progress of the local infection. Flow cytometry and immunohistochemistry revealed the participation of γδT cells in the immune response. In conclusion, we did see a graded inflammatory response associated with the dose of s.c. inoculated bacteria, which may be useful for studying, in particular, the interaction of bacteria and inflammatory mononuclear cell populations. It needs to be investigated if the model is discriminatory and robust., (© 2020 Scandinavian Societies for Medical Microbiology and Pathology.)

The present study investigated the position-specific match demands and heart rate response of female elite footballers, with special focus on the full-game, end-game, and peak-intensity periods. In total, 217 match observations were performed in 94 players from all eight teams of the best Danish Women's League, that is, goalkeepers (GK, n = 10), central defenders (CD, n = 23), full-backs (FB, n = 18), central midfielders (CM, n = 28), external midfielders (EM, n = 18), and forwards (FW, n = 11). Positional data (GPS; 10 Hz Polar Team Pro) and HR responses were collected. HR mean and HR peak were 87%-89% and 98%-99% of HR max , for outfield players, with no positional differences. CM, EM, and FB covered 8%-14% greater (P < .001) match distances than CD. EM, FW, FB, and CM performed 40%-64% more (P < .05) high-speed running and 41%-95% more (P < .01) very-high-speed running (VHSR) than CD. From the first to the last 15-minute period, total distance, except for FW, number of VHSR, except FB, peak speed and sum of accelerations and sum of decelerations decreased (P < .05) for all outfield positions. In the most intense 5-minute period, EM, FB, and CM performed 25%-34% more (P < .01) HSR than CD, whereas EM, FW, and FB performed 36%-49% more (P < .01) VHSR than CD. In conclusion, competitive elite female matches impose high physical demands on all outfield playing positions, with high aerobic loading throughout matches and marked declines in high-speed running and intense accelerations and decelerations toward the end of games. Overall physical match demands are much lower for central defenders than for the other outfield playing positions, albeit this difference is minimized in peak-intensity periods., (© 2020 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

We determined player-to-player distance, body-to-ball contact, and exercise intensity during three training modalities in various football populations. 213 participants were recruited, ranging from 9-year-old boys to young men and 11-year-old girls to middle-aged women. All groups were analysed with video-filming and GPS-based Polar Pro monitors during three types of football training for 20 min, i.e., COVID-19-modified training (CMT) with >2-metre player-to-player distance, small-sided games (SSG), and simulated match-play with normal rules (SMP), in randomised order. Time spent in a danger zone (1.5 m) per-percent-infected-player (DZ PPIP) ranged from 0.015 to 0.279% of playing time. DZ PPIP for SSG was higher ( P < 0.05) than CMT and SMP. The average number of contacts (within 1.5 m) with a potentially infected player ranged from 12 to 73 contacts/hour. SSG had more ( P < 0.05) contacts than CMT and SMP, with SMP having a higher ( P < 0.05) number of contacts than CMT. Time/contact ranged from 0.87 to 3.00 seconds for the groups. No player-to-player and body-to-ball touches were registered for CMT. Total player-to-player contacts were 264% higher ( P < 0.05) in SSG than SMP, ranging from 80 to 170 and 25 to 56 touches, respectively. In all groups, a greater total distance was covered during SMP compared to CMT (38-114%; P < 0.05). All groups performed more high-intensity running (33-54%; P < 0.05) and had higher heart rates during SMP compared to CMT. Different types of football training all appear to exert a minor COVID-19 infection risk; however, COVID-19-modified training may be safer than small-sided game training, but also match-play. In contrast, exercise intensity is lower during COVID-19-modified training than match-play., Competing Interests: The authors declare that there is no conflict of interests regarding the publication of this paper., (Copyright © 2022 Magni Mohr et al.)

Determination of the surface temperature of different materials based on thermographic imaging is a difficult task as the thermal emission spectrum is both temperature and emissivity dependent. Without prior knowledge of the emissivity of the object under investigation, it makes up a temperature-emissivity underdetermined system. This work demonstrates the possibility of recognizing specific materials from hyperspectral thermal images (HSTI) in the wavelength range from 8-14 µm. The hyperspectral images were acquired using a microbolometer sensor array in combination with a scanning 1 st order Fabry-Pérot interferometer acting as a bandpass filter. A logistic regression model was used to successfully differentiate between polyimide tape, sapphire, borosilicate glass, fused silica, and alumina ceramic at temperatures as low as 34.0 ± 0.05 °C. Each material was recognized with true positive rates above 94% calculated from individual pixel spectra. The surface temperature of the samples was subsequently predicted using pre-fitted partial least squares (PLS) models, which predicted all surface temperature values with a common root mean square error (RMSE) of 1.10 °C and thereby outperforming conventional thermography. This approach paves the way for a practical solution to the underdetermined temperature-emissivity system.

The "11 for Health in Denmark" concept aims to enhance 10-12-year-old schoolchildren's physical activity levels and health knowledge through an 11-week football intervention and has been shown to induce positive effects in numerous areas. However, little is known about the implementation facilitation of this concept in schools. This case study therefore aims to gain a deeper understanding of the implementation facilitation of "11 for Health" in a Danish 5 th grade class comprising 22 schoolchildren (12 boys and 10 girls, M age 11.86±) and one teacher. Data were derived from multiple school situations using photographs and videos, observations, and informal interviews. Five themes were identified: (1) environmental and organizational factors impacting on the implementation; (2) familiarization with the concept for the teacher and schoolchildren; (3) previous clique formation; (4) the central role of the teacher; and (5) the importance of how praise partners are allocated. We found high adherence to the "11 for Health" concept, in which the teacher played a key role by applying an autonomy-supportive style of teaching and using the praise partner concept in a suitable manner. A clique of football-playing boys was a resource, as their praising of classmates encouraged adherence. However, familiarization with the "11 for Health" concept was a challenge and the clique's competitive nature occasionally built barriers to other schoolchildren without football experience, potentially leading to a more controlled form of motivation. Based on the results, we encourage teachers to apply autonomy-supportive teaching when applying the "11 for Health" concept., (© 2021 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Objectives: This study investigated the effects of the health promotion intervention "11 for Health in Denmark" program on 10- to 12-year-old ethnic minority schoolchildren's enjoyment, health knowledge, well-being, and fitness., Methods: 1122 Danish 5th grade schoolchildren with ethnic minority background from 154 schools were randomized (5:1) to an intervention group (IG, n = 944) or a control group (CG, n = 178). The IG and CG were also divided into subgroups of children active in a sports club (IGPA: n = 644; CGPA: n = 122) and not active in a sports club (IGPI: n = 300, CGPI: n = 56). IG participated in the "11 for Health in Denmark" 11-week program, consisting of 2 × 45 min per week of football drills, small-sided games, and health education, whereas CG continued their regular activities. Pre-post physical testing and questionnaires were applied (short version of the multidimensional well-being questionnaire KIDSCREEN-27, and a 34-item health knowledge questionnaire)., Results: The "11 for Health in Denmark" program was rated moderate-to-high on a 1-5 scale for enjoyment by girls (3.57) and boys (3.65). The intervention had positive between-group effect on health knowledge in relation to hygiene (IG vs GC: 10.6% points (CI95%: 6.9:14.3), p < 0.05), nutrition (9.6% point (CI95%: 7.4:11.8), p < 0.01) and physical activity 4.4% points (CI95%: 2.2:6.6) as well as overall health knowledge (5.7% points, (CI95%: 4.3;7.1), p < 0.05), with similar effects for girls and boys. The IGPI subgroup showed a positive effect on well-being (p = 0.04, school and learning) and also fitness effects on performance and VO 2  max (p = 0.02: p = 0.01). The IGPA subgroup showed a positive effect on fitness scores (p = 0.02, BMI)., Conclusion: The intervention program was enjoyable and had a positive impact on health knowledge of ethnic minority background schoolchildren. In addition, the intervention program had the strongest positive effects on well-being and fitness scores for the non-sports club-active children., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objectives: This study investigated the correlation between sports club activities and well-being and physical health parameters in 10-12 years old boys., Design: Cross sectional., Setting: Danish schools., Participants: 2293 boys took part in the study., Primary and Secondary Outcome Measures: Questionnaires on participation in sports clubs and well-being and testing of physical health profile through measurement of body composition, resting heart rate (RHR), blood pressure and postural balance, jump and Yo-Yo IR1C performance. Data were analysed by participation in sport and according to the five most frequently reported sports., Results: Boys enrolled in sports clubs had higher physical well-being (51.7±9.7 vs 45.9±8.7) and psychological well-being (53.3±9.6 vs 51.4±10.0), experienced more peers and social support (50.9±9.9 vs 48.0±11.6), and had a more positive perception of the school environment (48.6±7.5 vs 45.9±8.1) than boys not involved in sports clubs. In addition, they showed better Yo-Yo IR1C (+46%), long jump (9%) and balance test performance (+20%). The boys active in sports clubs had higher relative muscle mass (+6%) and lower fat percentage (-3%), body mass index (-6%) and RHR (-5%) compared with boys not involved in sports clubs (p<0.05). Boys enrolled in football clubs had higher aerobic fitness compared with boys not active in clubs (+11%), handball players (+5%), swimmers (+8%) and badminton players (+7%). Moreover, the boys enrolled in football clubs had lower fat percentage (-17%) and higher relative muscle mass (+4%) than swimmers., Conclusion: Boys participating in club-based sports showed markedly higher levels of well-being and better physical health profiles than boys not involved in sports club activities. Footballers had superior aerobic fitness and body composition compared with those active in other sports. Results suggest that sports club activities seem to be beneficial for young boys' well-being, fitness and physical health profile, with the greatest benefits achieved by boys involved in football., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

ObjectivesOur large-scale cluster randomised controlled trial aimed to investigate the effects on health knowledge and enjoyment of an 11 week 'health education through football' programme for children aged 10-12 years old. Methods 3127 Danish school children (49% girls) aged 10-12 years from a total of 154 schools located in 63% of the Danish municipalities (69 of 98) took part in the analysis. A 5:1 cluster randomisation was performed at school level for the intervention group (IG) or the control group (CG). The twice-weekly 45 min intervention was the '11 for Health in Denmark' programme, which includes health education, football drills and small-sided games. The health education element focused on hygiene, nutrition, physical activity and well-being. Outcomes: The participants completed a 34-item multiple-choice computer-based health knowledge questionnaire preintervention and postintervention. IG also evaluated whether the programme was enjoyable. Results Between-group differences (p<0.05) were observed in overall health knowledge in favour of IG (+7.2% points, 95% CI 6.1% to 8.4%, effect size, ES:0.59), with similar effects for girls (+7.4% points, 95% CI 5.9% to 9.0%, ES:0.57) and for boys (+7.0% points, 95% CI 5.3% to 8.7%, p<0.05, ES:0.51). Marked between-group differences were observed in favour of IG, for health knowledge related to hygiene (IG vs CG:+13.9% points, 95% CI 11.1% to 16.7%, ES:0.53), nutrition (+10.3% points, 95% CI 8.5% to 12.1%, ES:0.53), physical activity (+5.9% points, 95% CI 4.1% to 7.7%, ES:0.36) and well-being (+4.4% points, 95% CI 2.7% to 6.1%, ES:0.28). Both girls and boys gave the programme moderate to high scores for enjoyment (3.6±1.0 and 3.7±1.1, respectively). Conclusion Health education through sport, using the '11 for Health' model, was enjoyable for girls and boys aged 10-12 years old, and improved health knowledge related to hygiene, nutrition, physical activity and well-being., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

The purpose of this study was to quantify the exercise intensity and technical involvement of U9 boys' and girls' team handball during different game formats, and the differences between genders. Locomotor activity (total distance, distance in speed zones, accelerations, and decelerations), heart rate (HR), and technical involvement (shots, goals, and duels) metrics were collected during various 15 min game formats from a total of 57 Danish U9 players (37 boys and 20 girls). Game formats were a small size pitch (20 × 13 m) with 3 vs. 3 players and offensive goalkeepers (S3 + 1) and 4 vs. 4 players (S4), a medium size pitch (25.8 × 20 m) with 4 vs. 4 (M4) and 5 vs. 5 (M5) players, and a large size pitch (40 × 20 m) with 5 vs. 5 (L5) players. Boys and girls covered a higher total distance (TD) of high-speed running (HSR) and sprinting during L5 games compared to all other game formats ( p < 0.05; ES = (-0.9 to -2.1), (-1.4 to -2.8), and (-0.9 to -1.3) respectively). Players covered the highest amount of sprinting distance in L5 games compared to all other game formats ( p < 0.01; ES = 0.8 to 1.4). In all the game formats, players spent from 3.04 to 5.96 min in 180-200 bpm and 0.03 min to 0.85 min in >200 bpm of the total 15 min. In addition, both genders had more shots in S3 + 1 than M5 ( p < 0.01; ES = 1.0 (0.4; 1.7)) and L5 ( p < 0.01; ES = 1.1 (0.6; 2.2)). Team handball matches have high heart rates, total distances covered, and high-intensity running distances for U9 boys and girls irrespective of the game format. Locomotor demands appeared to be even higher when playing on larger pitches, whereas the smaller pitch size and fewer players led to elevated technical involvement.

The aim of this study was at examining the validity and reliability of a marketed bioimpedance (BIA) scale for body composition assessment, in children engaged in an educational football project (FIFA 11 for Health). One-hundred and twenty-seven children (70 boys and 57 girls; age 10.7±0.5 years, body mass 41.2±9.0 kg, Body mass index 18.5±3.3 kg·m-2 and stature 149±7 cm) were evaluated for total body mass, lean body mass, muscle mass, using BIA (InBody 270, Biospace, California, USA) and dual-energy X-ray absorptiometry (DEXA, Lunar Prodigy, GE Medical Systems, Madison, Wisconsin, USA), at baseline conditions. Data analyses were carried out separately for girls and boys. Nearly perfect associations (r = 0.97-0.99) and excellent absolute (TEM = 0.04-1.9%) and relative (ICC = 0.98-1.00) inter-device reliability were found between DEXA and BIA variables. Fat and lean body mass bias (p < .0001) were practically relevant both for the boys (2.56 and 11.22 kg, respectively) and the girls (2.33 and 10.49 kg, respectively). Muscle mass and body fat were underestimated and overestimated, respectively, for the boys and girls. InBody 270 is a valid BIA system for estimating body composition with an excellent inter-device relative and absolute reliability. However, the remarkable measurements bias of BIA fat and muscle mass values discourage its use for clinical prescription. The BIA body composition biases were sex dependent., Competing Interests: No competing interest.

Purpose: This study aimed to compare performance on sand and a firm surface and to describe the physical capacity of male and female beach soccer players. Methods: Sixty-six male and 29 female competitive beach soccer players voluntarily participated in this study. Firstly, within-subjects test scores were compared to scores on a firm surface (criterion validity; n = 15 men) and reconducted on a second occasion (reliability; n = 51 men). Secondly, the best score on sand was retained to compare test performance between ages (classified as below 20, 20-30, and above 30 years) and sexes. Performance assessments included sprint time over 5 and 15 m (once on a firm surface and twice on sand), standing long jump (SLJ, once on a firm surface and twice on sand) and Yo-Yo intermittent recovery level 1 (Yo-Yo IR1, once on a firm surface and once on sand; only data for men were available). Results: Five-m sprint and Yo-Yo IR1 performance on sand were not correlated to performance on a firm surface ( P > 0.05). Test-retest reliability was acceptable for the 15-m sprint and SLJ tests (ICC > 0.90; CV < 5%). Performance in 15-m sprint and maximal sprinting speed were moderately lower in male players aged above 30 years. compared to players aged below 30 years ( d = 0.35-0.42; P < 0.05). Irrespective of the age group, weight-bearing power-based performance mass was moderately to very largely higher in male players than in female players ( d = 0.42-0.88; P < 0.05). Conclusions: The lack of a consistent relationship between performance on sand and on a firm surface might indicate the need to develop specific test batteries for sand-based athletes. Age-related differences in physical performance were evident only in sprint capacity. Further studies are warranted to elucidate our preliminary findings and to develop the sand specific tests., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Larsen, Ermidis, Brito, Ørner, Martins, Lemos, Krustrup and Rago.)

During the COVID-19 pandemic, physical inactivity has increased, and a wide range of sporting activities locked down, with possible long-term implications for public health. Football is the most popular sport worldwide, and recreational football training leads to broad-spectrum health effects. Football is, however, deemed a contact sport with frequent close contact important to consider during COVID-19 pandemic., Objectives: This study investigated time spent with close contact (danger zone (DZ) within 1.5 m), number of contacts and time per contact, and compared game formats in recreational small-sided football games for young and adult male football players., Methods: Movement analyses were performed on 10 Hz Global Positioning System (GPS) data collected during various small-sided football games prior to the COVID-19 outbreak., Results: Time spent in the DZ was 4.3-7.9 s/h per per cent infected players, corresponding to 34.3-114.8 s/h if one player was infected. Number of contacts with one infected player was 23.5-87.7 per hour, with an average contact time of 1.1-1.4 s, and a total number of contacts of 311-691 per hour with all players. 53%-65% of all contacts were shorter than 1 s and 77%-85% shorter than 2 s. Trivial to small effects were found for number of participants and area per player, whereas standard of play and playing with/without boards had no effect., Conclusion: This study demonstrated that during small-sided football limited time is spent within DZ and that player contacts are brief. Recreational football may therefore more appropriately be deemed as sporting activity with brief, sporadic contact., Competing Interests: Competing interests: PK is employed by the Danish Football Association as fitness coach for the women’s national team. MM is fitness coach for the Faroese men's national football team., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The present study examined cardiovascular adaptations in 8-10-year-old schoolchildren after a full school year (10 months) of 5 × 12 min/wk. of intense physical training, including small-sided ball games (soccer, basketball and floorball) or interval running. The study involved 8-10-year-old healthy Danish schoolchildren (n = 232), who were cluster-randomized to a small-sided games group (SSG, n = 60), an interval running group (IR, n = 57) or a control group (CON, n = 115). Comprehensive transthoracic echocardiography, resting heart rate and blood pressure measurements were performed at baseline and post intervention. For interval running, analysis of baseline-to-10-months changes showed significant (P < 0.05) between-group differences in delta scores for diastolic blood pressure (BP) and mean arterial BP (IR -3.2 ± 5.7 and - 2.2 ± 6.5 mmHg vs. CON 0.2 ± 5.3 and 0.4 ± 6.4 mmHg, respectively). Delta scores also showed a trend for reduction of mean arterial BP in SSG compared to CON (-2.1 ± 6.0 vs. 0.2 ± 5.3 mmHg, P = 0.067). Moreover, there were between-group differences in delta scores (P < 0.05) for selected echocardiographic parameters, i.e. in SSG vs. CON for interventricular septum thickness and peak transmitral flow velocity in early diastole, and in IR vs. CON for left ventricular systolic diameter. In conclusion, 10 months of 5 × 12 min/wk. of IR in 8-10-year-old children decreased diastolic BP, while both IR and SSG elicited cardiac adaptations. The results suggest that frequent low volume, intense physical training can have effects on the cardiovascular health profile in healthy children., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Motor skill acquisition depends on central nervous plasticity. However, behavioural determinants leading to long lasting corticospinal plasticity and motor expertise remain unexplored. Here we investigate behavioural and electrophysiological effects of individually tailored progressive practice during long-term motor skill training. Two groups of participants practiced a visuomotor task requiring precise control of the right digiti minimi for 6 weeks. One group trained with constant task difficulty, while the other group trained with progressively increasing task difficulty, i.e. continuously adjusted to their individual skill level. Compared to constant practice, progressive practice resulted in a two-fold greater performance at an advanced task level and associated increases in corticospinal excitability. Differences were maintained 8 days later, whereas both groups demonstrated equal retention 14 months later. We demonstrate that progressive practice enhances motor skill learning and promotes corticospinal plasticity. These findings underline the importance of continuously challenging patients and athletes to promote neural plasticity, skilled performance, and recovery.

Background: The present study investigates the well-being effects for 10- to 12-year-old children  who participated in the school-based intervention "11 for Health in Denmark," which comprises physical activity (PA) and health education. Subgroup analyses were carried out for boys and girls., Method: Three thousand sixty-one children were randomly assigned to an intervention group (IG) or a control group (CG) by 5:1 cluster randomization by school. 2533 children (mean age 11.5 ± 0.4; 49.7% boys) were assigned to IG and 528 children (mean age 11.4 ± 0.5; 50.8% boys) were assigned to CG. IG participated in the "11 for Health in Denmark" 11-week program, consisting of 2 × 45 min per week of football drills, small-sided games, and health education. CG did not participate in any intervention and continued with their regular education. Before and after the intervention period, both groups answered a shortened version of the multidimensional well-being questionnaire KIDSCREEN-27., Results: The "11 for Health in Denmark" intervention program had a positive effect on physical well-being in girls (IG: 48.6 ± 8.5 to 50.2 ± 9.3), whereas the improvement was not significant in boys. The program also had a positive impact on well-being scores for peers and social support (IG: 50.2 ± 10.2 to 50.8 ± 10.1), though when analyzed separately in the subgroups of boys and girls the changes were not significant. No between-group differences were found for psychological well-being or school environment., Conclusion: The intervention program had a positive between-group effect on physical well-being in girls, whereas the change was not significant in boys. The overall scores for peers and social support improved during the intervention period, but no subgroup differences were found., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

To assess the real-life magnitude of the heading incidence in children's and youth' football in eight European countries with different "football cultures," a cross-sectional observational design, in which one match per team in 480 different teams from eight European countries (2017/18-2018/19), was recorded by video. One training session was recorded in 312 teams. Clubs with Under-10, Under-12 (female/male/mixed), and Under-16 female and male teams were eligible to participate. Heading frequencies and types were analyzed. Results are presented as headers per match/training and per team. Incidence rates (IR) per 1000 match/training hours were calculated. Under-10 teams carried out the lowest average number of headers per match (8.8), followed by Under-16 female (17.7), Under-12 (18.4), and Under-16 male (35.5). Total number of headers per match and team varied between countries. 80% of the total number of headers were single intentional headers, 12% heading duels, 3% unintentional headers by getting hit, and 5% others (trends apparent in all age groups). Three head injuries occurred during match play corresponding to an IR of 0.70 (95% CI, 0.23-2.16). The lowest number of headers per training and team was found in Under-10 (21.3), followed by Under-16 females (34.1), Under-12 (35.8), and Under-16 males (45.0). In conclusion, this large-scale study presents novel data about the number and type of headers in youth' football throughout Europe. A more precise understanding of the heading incidence, specifically in young players, is mandatory for the debate of restrictions on heading in youth football., (© 2020 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

The aim of the study was to compare the activity pattern, heart rate (HR), technical involvement, and subjective perceptions in U13 boys and girls playing team handball in five game formats. Activity pattern, heart rate (HR), technical involvement, perceived fun, and exertion were recorded from four girls teams (n = 24) and four boys teams (n = 24) played during a 1-day tournament consisting of five different game formats of 15-min duration: Medium court size, 4v4 (M4v4), 5v5 (M5v5), and 6v6 (M6v6), and large court size, 5v5 (L5v5) and 6v6 (L6v6). Girls covered more total distance (TD) and high-speed running (HSR, 13-17.9 km·h -1 ) on the large court compared to the medium court ( p < 0.05; ES = 2.1-3.1 and 1.2-2.5, respectively). Boys covered more distance as HSR and sprinting on the large court compared to the medium court, but only more TD on the large court compared to the medium court with the same number of players, ( p < 0.05; ES = 1.0-1.8, 1.0-1.8, and 1.1-1.8, respectively). Team handball for U13 boys and girls is a high-intensity activity irrespective of court size. Increasing the court size with a fixed number of players increased the total distance and HSR, whereas manipulating the number of players on a fixed court size appears to influence technical involvement.

This study investigated whether the physical fitness and body composition of 10-12-year-old Danish children are related to participation in leisure-time club-based sporting activities. The study involved 544 Danish 10-12-year-old 5th-grade municipal schoolchildren (269 boys and 275 girls, 11.1 ± 0.4 years). After answering a questionnaire about leisure-time sporting activities, the children were divided into four groups: football club participation (FC; n=141), other ball games (OBG; n=42), other sports (OS; n=194), and no sports-club participation (NSC; n=167). The children completed a battery of health and fitness tests, including a 20 m sprint test, a standing long-jump test, the Yo-Yo IR1 children's test (YYIR1C), and body composition, blood pressure, resting heart rate (HR rest ), and the flamingo balance test. The children engaged in club-based ball games (FC and OBG) had higher (p<0.05) lean body mass than NSC (FC: 17.5 ± 2.9; OBG: 18.4 ± 2.6; OS: 16.7 ± 2.9; NSC: 16.4 ± 2.8 kg), performed better (p<0.05) in the YYIR1C test (FC: 1083 ± 527; OBG: 968 ± 448; OS: 776 ± 398; NSC: 687 ± 378 m), and had lower (p<0.05) %HR max after 1, 2, and 3 min of YYIR1C. Moreover, HR rest was lower (p<0.05) for FC than for OS and NSC (FC: 68 ± 9 vs OS: 72 ± 10 and NSC: 75 ± 10 bpm), and lower (p<0.05) for OBG than for NSC (OBG: 70 ± 10 vs NSC: 75 ± 10 bpm). This study found that 10-12-year-old Danish children engaged in club-based football and other ball games had better exercise capacity, lower resting heart rate, and higher muscle mass than children not engaged in leisure-time sports. Thus, participation in club-based leisure-time ball-game activities seems to be of importance for the fitness and health profile of prepubertal children.

Purpose: To examine the reliability of age-adapted submaximal Yo-Yo (Yo-Yo submax ) intermittent tests in untrained schoolchildren aged 9-16 years (n = 139; 72 boys and 67 girls) and within children with high and low percentage of body fat (%BF)., Methods: Yo-Yo intermittent recovery level 1 children's (YYIR1C), Yo-Yo intermittent endurance level 1 (YYIE1), and Yo-Yo intermittent endurance level 2 (YYIE2) tests were performed 7 days apart by 9- to 11-, 12- to 13-, and 14- to 16-year-old children, respectively. Reliability was tested for Yo-Yo submax heart rate (HR submax ), peak HR, and maximal distance., Results: HR submax typical errors of measurement (TEM) in YYIR1C, YYIE1, and YYIE2 were 2.2% (1.7%-2.9%), 2.4% (1.9%-3.3%), 1.9% (1.6%-2.5%) and 2.4% (1.9%-3.3%), 2.4% (1.9%-3.2%), 1.9% (1.5%-2.4%) for girls and boys, respectively. HR submax intraclass correlation coefficient values were good to excellent (.62-.87) in all age groups and in schoolchildren of different %BF. TEM for HR submax ranged from 2.1% to 2.3% in high and low %BF groups. Maximal distance intraclass correlation coefficients were excellent and TEM values ranged from 11% to 12% in both %BF groups. HR submax was moderately to largely associated (r = -.46 to -.64; P < .002) with Yo-Yo maximal distance across the age groups., Conclusion: Yo-Yo submax tests are a reliable tool providing useful and sustainable aerobic performance testing in physical education, irrespective of individual %BF., (2018 Human Kinetics, Inc.)

This study examines heart rate (HR) and perceived experience during same- versus mixed-gender soccer played as small- (SSG) and large-sided (LSG) games. HR, rating of perceived exertion (RPE), and fun scores were determined in 134 pupils (50 girls, 84 boys) randomly assigned to same- and mixed-genders formats playing 2x15-min of SSG (2v2, 4v4) and LSG (12v12) in a random order (~50 m 2 /player). HR was lower ( p ≤0.03) for girls when playing together with boys than when playing alone (71±10 versus 77±7%HRmax), while being similar for boys playing mixed- or same-gender games (74±7 versus 77±4%HRmax). Boys perceived less fun when playing together with girls than when playing alone (4.4±2.3 versus 6.3±2.3, p <0.001). Irrespective of gender, higher ( p <0.001) HRmean, %time>80%HRmax, and RPE were observed during 2v2 (78±9%HRmax, 43±33%, 5.5±2.5) and 4v4 (76±9%HRmax, 39±32%, 5.5±2.7) than during 12v12 (70±10%HRmax, 23±27%, 3.8±2.9). Cardiovascular strain was lower for girls when playing together with boys than when playing alone in LSG. SSG were more intense than LSG when girls played mixed-gender games and when boys played mixed- and same-gender games. When boys played mixed-gender games, SSG were considered more fun than LSG. Physical education teachers and coaches should consider gender and game format differences when using soccer.

We evaluated effects of the school-based intervention "FIFA 11 for Health" for Europe on health and fitness profile in 10- to 12-year-old Faroese schoolchildren. 392 fifth-grade children were randomized into a control group (CG: n = 100, 11.1 ± 0.3 years, 149.0 ± 6.7 cm, 42.4 ± 10.2 kg) and an intervention group (IG: n = 292, 11.1 ± 0.3 years, 150.6 ± 6.9 cm, 44.2 ± 9.4 kg). IG underwent an 11-week intervention in which 2 weekly sessions of 45 minutes were included in the school curriculum focusing on health aspects, football skills, and 3v3 small-sided games. CG continued with their regular activities. Body composition, blood pressure, and resting heart rate, as well as Yo-Yo intermittent recovery children's test (YYIR1C) performance, horizontal jumping ability and postural balance were assessed pre and post intervention. Systolic blood pressure decreased more (-2.8 ± 9.9 vs 2.9 ± 8.4 mm Hg, P < .05) in IG than in CG. Lean body mass (1.0 ± 1.7 vs 0.7 ± 1.6 kg), postural balance (0.3 ± 3.9 vs -1.2 ± 5.9 seconds) and horizontal jump performance (5 ± 9 vs -5 ± 10 cm) increased more (P < .05) in IG than in CG. YYIR1C performance improved in CG (17%, 625 ± 423 to 730 ± 565 m) and IG (18%, 689 ± 412 vs 813 ± 391 m), but without between-group differences. A within-group decrease from 23.1 ± 8.4 to 22.5 ± 8.3% (P < .05) was observed in body fat percentage in IG only. In conclusion, the "FIFA 11 for Health" for Europe program had beneficial effects on SBP, body composition, jump performance and postural balance in 10- to 12-year-old Faroese schoolchildren, supporting the notion that school-based football interventions can facilitate health of children in a small-scale society and serve as an early step in the prevention of non-communicable diseases., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

This study examined cardiovascular adaptations in 8- to 10-year-old schoolchildren after 10 months (a full school year) of 3 × 40 minute per week of small-sided ball games (SSG, including football, basketball, and/or floorball) or circuit strength training (CST). The study involved 291 Danish schoolchildren, 8-10 years old, cluster-randomized to SSG (n = 93, 4 schools, 5 classes), CST (n = 83, 4 schools, 4 classes), or a control group (CON, n = 115, 2 schools, 5 classes). Before and after the 10-month intervention, resting heart rate and blood pressure measurements were performed as well as comprehensive transthoracic echocardiography and peripheral arterial tonometry (PAT). Analysis of baseline-to-10-months changes showed between-group differences (P < 0.05) after both training interventions in diastolic blood pressure (delta scores: SSG -2.1 ± 6.0 mm Hg; CST -3.0 ± 7.1 mm Hg; CON 0.2 ± 5.3 mm Hg). Moreover, there were between-group differences in delta scores (P < 0.05) in interventricular septum thickness (SSG 0.17 ± 0.87 mm; CST 0.30 ± 0.94 mm; CON -0.15 ± 0.68 mm), left-atrial volume index (SSG 0.32 ± 5.13 mL/m 2 ; CON 2.60 ± 5.94 mL/m 2 ), and tricuspid annular plane systolic excursion (SSG -0.4 ± 3.3 mm; CON: 0.1 ± 3.6 mm). No significant between-group differences were observed for the PAT-derived reactive hyperemia index. In conclusion, 10 months of 3 × 40 minutes per week of SSG and CST in 8- to 10-year-old children decreased diastolic blood pressure and elicited discrete cardiac adaptations, suggesting that intense physical exercise in school classes can have effects on cardiovascular health in children., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: Recent studies have shown promising effects of physical activity on cognitive function, but there is a need to investigate this link in real-life settings such as schools. Hence, the objective of the present pilot study was to investigate whether the school-based physical activity programme "FIFA 11 for Health" for Europe could improve cognitive performance in preadolescent Danish children., Methods: The pilot study used an 11-week cluster-randomised intervention study design. School classes were randomly assigned to either a control group (CG) (n = 93 children, age = 11.8, s = 0.2 years), which performed the obligatory daily school-based physical activity (5 × 45 minutes per week); or an intervention group (IG) (n = 838 children, age = 11.9, s = 0.4 years), which substituted 2 × 45 minutes per week of the daily school physical activity with the "FIFA 11 for Health" for Europe programme. The programme combines small-sided football games, drills and health education. Cognitive performance was evaluated at baseline and follow-up., Results: The IG improved their cognitive performance compared to the CG for psychomotor function (56, s x -  = 22 ms, p < .001), attention (39, s x -  = 17 ms, p = .012) and working memory (79, s x -  = 35 ms, p = .020)., Conclusion: This pilot study provides evidence that the school-based physical activity programme "FIFA 11 for Health" for Europe can improve cognitive performance in preadolescent Danish schoolchildren. Future studies should attempt to disentangle the effects of "FIFA 11 for Health" for Europe on cognitive performance by investigating the characteristics of the programme's physical activity.

Objectives: We investigated whether musculoskeletal fitness of school children aged 8-10 years was affected by frequent intense PE sessions., Design and Participants: 295 Danish school children aged 8-10 years were cluster randomised to a small-sided ball game group (SSG) (n=96, four schools, five classes), a circuit strength training group (CST) (n=83, four schools, four classes) or a control group (CON, n=116, two schools, five classes)., Intervention: SSG or CST was performed 3×40 min/week over 10 months. Whole-body dual-energy X-ray absorptiometry (DXA) scans were used to determine areal bone mineral density (aBMD), bone mineral content (BMC) and lean body mass (LBM). Flamingo balance, standing long jump and 20-m sprint tests were used to determine muscular fitness., Results: Analysis of baseline-to-10 months change scores showed between-group differences in favour of the interventions in whole-body aBMD (SSG vs CON: 8 mg/cm 2 , 95% CI 3 to 13; CST vs CON: 7 mg/cm 2 , 95% CI 2 to 13, p<0.05) and leg BMC (SSG vs CON: 11 g, 95% CI 4 to 18; CST vs CON: 11 g, 95% CI 3 to 18, p<0.05). SSG had higher change scores in leg aBMD compared with CON and CST (SSG vs CON: 19 mg/cm 2 , 95% CI 11 to 39, p<0.05; SSG vs CST: 12 mg/cm 2 , 95% CI 3 to 21, p<0.05), and CST had higher change scores in whole-body BMC compared with CON (CST vs CON: 25 g, 95% CI 10 to 39, p<0.05). Both training types resulted in higher change scores in postural balance (SSG vs CON: 2.4 fewer falls/min, 95% CI 0.3 to 4.5, CST vs CON: 3.6 fewer falls/min, 95% CI 1.3 to 5.9, p<0.05) and jump length (SSG vs CON: 10%, 95% CI 5 to 16%; CST vs CON: 9%, 95% CI 3 to 15%, p<0.05). No between-group differences were observed for sprint performance or LBM (p>0.05)., Conclusions: In conclusion, 3×40 min/week with SSG or CST over a full school year improves bone mineralisation and several aspects of muscular fitness of children aged 8-10 years, suggesting that well-organised intense physical education classes can contribute positively to develop musculoskeletal health in young children., Trial Registration Number: NCT02000492, post results., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Larsen, MN, Nielsen, CM, Ørntoft, CØ, Randers, M, Manniche, V, Hansen, L, Hansen, PR, Bangsbo, J, and Krustrup, P. Physical fitness and body composition in 8-10-year-old Danish children are associated with sports club participation. J Strength Cond Res 31(12): 3425-3434, 2017-We investigated whether physical fitness and body composition in 8-10-year-old Danish children are associated with sports club participation. The study included 423 schoolchildren, comprising 209 girls and 214 boys, of whom 67 and 74%, respectively, were active in sports clubs. Yo-Yo intermittent recovery level 1 for children (YYIR1C), balance, jump and coordination tests, together with dual-energy X-ray absorptiometry, were used to determine exercise capacity and body composition. Children active in sports clubs had better (p < 0.05) YYIR1C (33%, 767 ± 26 vs. 575 ± 29 m), 20-m sprint (3%, 4.33 ± 0.03 vs. 4.48 ± 0.04 seconds), coordination (6%, 68 ± 1 vs. 72 ± 1 second), and balance test performances (9%, 19.3 ± 0.5 vs. 21.2 ± 0.7 falls·min) and lower fat mass index (16%, 3.8 ± 0.1 vs. 4.5 ± 0.2 kg[fat]·m) than children not active in sports clubs. Ball game players had better (p < 0.05) YYIR1C (38%, 925 ± 39 vs. 671 ± 28 m), 20-m sprint (4%, 4.25 ± 0.03 vs. 4.42 ± 0.04 seconds), and coordination test performances (5%, 65 ± 1 vs. 69 ± 1 second), along with higher (p < 0.05) lean body mass (5%, 24.00 ± 0.22 vs. 22.83 ± 0.25 kg) and whole-body BMD (2%, 0.90 ± < 0.01 vs. 0.88 ± <0.01 g·cm) compared with children active in other sports. The study showed that 8[FIGURE DASH]10-year-old Danish children engaged in sports-club activity, especially ball game players, have better exercise capacity and superior body composition compared with children not active in sports clubs.

Aim: To modify the 'FIFA 11 for Health' programme to the European situation, and to assess its effects on health knowledge and well-being in Danish school children., Method: A two-cohort study with seven intervention and two control schools. Of the 546 Danish children (boys 269; girls 277) of mean age 11.1 (±0.4) years from five city and four country-side schools, 402 undertook the 'FIFA 11 for Health' programme and 144 acted as controls. As part of each school's PE curriculum, seven intervention schools received a 45 min Play Football period (football skills and 3 vs 3 games) and a 45 min Play Fair period (health issues and football drills) on a weekly-basis for 11 weeks. Control participants continued with their regular school PE activities. Participants completed preintervention and postintervention health knowledge and well-being questionnaires., Results: Overall, health knowledge increase was significantly (p<0.05) greater for the intervention group (11.9%) than the control group (2.6%). Significant (p<0.05) between-group differences were obtained for 8 of 10 health topics (6.1-20.2%) related to physical activity, nutrition, hygiene and well-being. The social dimension of the well-being questionnaire was significantly (p<0.05) improved in the intervention group compared to the control group, but there were no significant between-group effects for the physical, emotional and school dimensions. Positive reporting about the programme was given by 72.4% of the children and only 4.8% reported negatively., Conclusions: The 'FIFA 11 for Health' programme modified for Europe demonstrated positive effects on children's health knowledge and social dimension of well-being, thereby providing evidence that the football-based health education programme can be used effectively within a European school's curriculum to increase physical activity, well-being and health knowledge., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

It is well established that unilateral motor practice can lead to increased performance in the opposite non-trained hand. Here, we test the hypothesis that progressively increasing task difficulty during long-term skill training with the dominant right hand increase performance and corticomotor excitability of the left non-trained hand. Subjects practiced a visuomotor tracking task engaging right digit V for 6 weeks with either progressively increasing task difficulty (PT) or no progression (NPT). Corticospinal excitability (CSE) was evaluated from the resting motor threshold (rMT) and recruitment curve parameters following application of transcranial magnetic stimulation (TMS) to the ipsilateral primary motor cortex (iM1) hotspot of the left abductor digiti minimi muscle (ADM). PT led to significant improvements in left-hand motor performance immediately after 6 weeks of training (63 ± 18%, P < 0.001) and 8 days later (76 ± 14%, P < 0.001). In addition, PT led to better task performance compared to NPT (19 ± 15%, P = 0.024 and 27 ± 15%, P = 0.016). Following the initial training session, CSE increased across all subjects. After 6 weeks of training and 8 days later, only PT was accompanied by increased CSE demonstrated by a left and upwards shift in the recruitment curves, e.g. indicated by increased MEP max (P = 0.012). Eight days after training similar effects were observed, but 14 months later motor performance and CSE were similar between groups. We suggest that progressively adjusting demands for timing and accuracy to individual proficiency promotes motor skill learning and drives the iM1-CSE resulting in enhanced performance of the non-trained hand. The results underline the importance of increasing task difficulty progressively and individually in skill learning and rehabilitation training., (© 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

This study investigates the enjoyment and cohesion of school children participating in a school-based high-intensity physical activity (PA) intervention. Both enjoyment and cohesion have been found to be important factors for adherence to regular physical and sport activity, an important outcome of PA interventions. The sample consisted of 300 pupils (mean age: 9.3 years; 52.7% female) assigned to a team sport intervention, an individual sport intervention, or a control group for 10 months. The Physical Activity Enjoyment Scale and Youth Sport Environment Questionnaire were used to measure enjoyment and cohesion. The Yo-Yo IR1C test determined fitness improvements. Results showed that enjoyment and cohesion (social) measured at the beginning of the intervention significantly predict fitness improvements achieved after 10 months. No differing developmental effects over time could be found in the intervention groups with regard to cohesion and enjoyment when comparing them to the control group. However, enjoyment and cohesion (social) significantly decreased in the groups that performed individual sports. Team sports seem to be more advantageous for the development of enjoyment and cohesion, which are both factors that positively impact the health outcomes of the intervention.

We investigated the exercise intensity and fitness effects of frequent school-based low-volume high-intensity training for 10 months in 8-10-year-old children. 239 Danish 3rd-grade school children from four schools were cluster-randomised into a control group (CON, n = 116) or two training groups performing either 5 × 12 min/wk small-sided football plus other ball games (SSG, n = 62) or interval running (IR, n = 61). Whole-body DXA scans, flamingo balance, standing long-jump, 20 m sprint, and Yo-Yo IR1 children's tests (YYIR1C) were performed before and after the intervention. Mean running velocity was higher ( p < 0.05) in SSG than in IR (0.88 ± 0.14 versus 0.63 ± 0.20 m/s), while more time ( p < 0.05) was spent in the highest player load zone (>2; 5.6 ± 3.4 versus 3.7 ± 3.4%) and highest HR zone (>90% HR max ; 12.4 ± 8.9 versus 8.4 ± 8.0%) in IR compared to SSG. After 10 months, no significant between-group differences were observed for YYIR1C performance and HR after 2 min of YYIR1C (HR submax ), but median-split analyses showed that HR submax was reduced ( p < 0.05) in both training groups compared to CON for those with the lowest aerobic fitness (SSG versus CON: 3.2%  HR max [95% CI: 0.8-5.5]; IR versus CON: 2.6%  HR max [95% CI: 1.1-5.2]). After 10 months, IR had improved ( p < 0.05) 20 m sprint performance (IR versus CON: 154 ms [95% CI: 61-241]). No between-group differences ( p > 0.05) were observed for whole-body or leg aBMD, lean mass, postural balance, or jump length. In conclusion, frequent low-volume ball games and interval running can be conducted over a full school year with high intensity rate but has limited positive fitness effects in 8-10-year-old children., Competing Interests: The authors declare that there are no competing interests.

Ørntoft, C, Larsen, MN, Andersen, TB, Rasmussen, LS, Póvoas, SCA, Randers, MB, and Krustrup, P. Technical actions, heart rate, and locomotor activity in 7v7 and 8v8 games for female youth soccer players. J Strength Cond Res 30(12): 3298-3303, 2016-The purpose of this study was to evaluate technical performance, heart rate (HR), and activity profile in 7v7 and 8v8 soccer games for 9- to 10-year-old girls (U11). A total of 24 female youth players participated in the study, all playing 20-minute 7v7 and 8v8 games with 160 and 223 m per player, respectively. Technical actions, HR, and activity profile were measured during the games using video filming, HR monitors, and 5-Hz Global positioning system (GPS) units. The number of technical actions was higher in 7v7 than in 8v8 games (34 ± 19 vs. 28 ± 14; p = 0.03; d = 0.37), as was the number of successful actions (25 ± 16 vs. 20 ± 12; p = 0.01; d = 0.35), with no difference in success rate for technical actions (70 ± 13 vs. 69 ± 14%; p = 0.63; d = 0.07). No differences were found between 7v7 and 8v8 in total distance covered (1,574 ± 251 and 1,622 ± 281 m; p = 0.66; d = 0.18), peak speed (19.5 ± 2.6 and 20.7 ± 1.5 km·h; p = 0.16; d = 0.56), mean HR values (85 ± 5 and 86 ± 6%HRpeak; p = 0.85; d = 0.18), and time of >90% HRpeak (37 ± 16 and 35 ± 14% of playing time; p = 0.70; d = 0.13). Distance covered at the highest running speeds of >16 km·h was lower in 7v7 than in 8v8 games (34 ± 24 vs. 63 ± 34 m; p = 0.018; d = 0.98), as was the number of entries into this speed zone (8 ± 5 vs. 13 ± 7; p = 0.006; d = 0.82). In conclusion, more technical actions and successful actions were observed in 7v7 than in 8v8 games, but players covered more ground with high-speed running in 8v8 games. This study also revealed that HR values were high in both game formats for U11 adolescent female players, with no difference between formats.

Objectives: To evaluate whether a modified 'FIFA 11 for Health' programme for non-communicable diseases had effects on body composition, blood pressure and physical fitness of Danish schoolchildren aged 10-12 years., Design: A cluster-randomised controlled study with 7 intervention and 2 control schools., Participants: 546 Danish 5th grade municipal schoolchildren allocated to an intervention group (IG; n=402: 11.1±0.4 (±SD) years, 150.1±7.0 cm, 41.3±8.4 kg) and a control group (CG; n=144: 11.0±0.5 years, 151.2±7.8 cm, 41.3±9.0 kg)., Intervention: As part of the physical education (PE) curriculum, IG carried out 2 weekly 45 min 'FIFA 11 for Health' sessions focusing on health issues, football skills and 3v3 games. CG continued regular school PE activities. Measurements of body composition, blood pressure at rest, Yo-Yo intermittent recovery level 1 children's test (YYIR1C), balance, jump and sprint performance were performed before and after the 11-week study period., Results: During the 11-week study period, systolic blood pressure (-3.5 vs 0.9 mm Hg), mean arterial blood pressure (-1.9 vs 0.4 mm Hg), body mass index (-0.02 vs 0.13 kg/m 2 ) and body fat percentage (-0.83% vs -0.04%) decreased more (p<0.05) in IG than in CG. Within-group improvements (p<0.05) were observed in IG for 20 m sprint (4.09±0.29 to 4.06±0.28 s) and YYIR1C performance (852±464 to 896±517 m), but these changes were not significantly different from CG, and balance or jump performance remained unchanged in both groups., Conclusions: The modified 'FIFA 11 for Health' programme has beneficial effects on body composition and blood pressure for Danish schoolchildren aged 10-12 years, thereby providing evidence that this football-based health education programme can directly impact participants' cardiovascular health profile., Competing Interests: Conflicts of Interest: None declared., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Objective: To investigate associations between motor skills, exercise capacity and cognitive functions, and evaluate how they correlate to academic performance in mathematics and reading comprehension using standardised, objective tests., Methods: This cross-sectional study included 423 Danish children (age: 9.29±0.35 years, 209 girls). Fine and gross motor skills were evaluated in a visuomotor accuracy-tracking task, and a whole-body coordination task, respectively. Exercise capacity was estimated from the Yo-Yo intermittent recovery level 1 children's test (YYIR1C). Selected tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) were used to assess different domains of cognitive functions, including sustained attention, spatial working memory, episodic and semantic memory, and processing speed. Linear mixed-effects models were used to investigate associations between these measures and the relationship with standard tests of academic performance in mathematics and reading comprehension., Results: Both fine and gross motor skills were associated with better performance in all five tested cognitive domains (all P<0.001), whereas exercise capacity was only associated with better sustained attention (P<0.046) and spatial working memory (P<0.038). Fine and gross motor skills (all P<0.001), exercise capacity and cognitive functions such as working memory, episodic memory, sustained attention and processing speed were all associated with better performance in mathematics and reading comprehension., Conclusions: The data demonstrate that fine and gross motor skills are positively correlated with several aspects of cognitive functions and with academic performance in both mathematics and reading comprehension. Moreover, exercise capacity was associated with academic performance and performance in some cognitive domains. Future interventions should investigate associations between changes in motor skills, exercise capacity, cognitive functions, and academic performance to elucidate the causality of these associations., Competing Interests: The research grants received from the FIFA Medical Assessment and Research Centre (F-MARC) and the Danish Football Association (DBU) does not alter our adherence to PLOS ONE policies on sharing data and materials.