Deconstructing athletes’sleep:A systematic review of the influence of age,sex,athletic expertise,sport type,and season on sleep characteristics

Purpose:This systematic review aimed to describe objective sleep parameters for athletes under different conditions and address potential sleep issues in this specific population.Methods:PubMed and Scopus were searched from inception to April 2019.Included studies measured sleep only via objective evaluation tools such as polysomnography or actigraphy.The modified version of the Newcastle-Ottawa Scale was used for the quality assessment of the studies.Results:Eighty-one studies were included,of which 56 were classified as medium quality,5 studies as low quality,and 20 studies as high quality.A total of 1830 athletes were monitored over 18,958 nights.Average values for sleep-related parameters were calculated for all athletes according to sex,age,athletic expertise level,training season,and type of sport.Athletes slept on average 7.2±1.1 h/night(mean±SD),with 86.3%±6.8%sleep efficiency(SE).In all datasets,the athletes’mean total sleep time was<8 h.SE was low for young athletes(80.3%±8.8%).Reduced SE was attributed to high wake after sleep onset rather than sleep onset latency.During heavy training periods,sleep duration and SE were on average 36 min and 0.8%less compared to pre-season and 42 min and 3.0%less compared to in-season training periods,respectively.Conclusion:Athletes’sleep duration was found to be short with low SE,in comparison to the general consensus for non-athlete healthy adults.Notable sleep issues were revealed in young athletes.Sleep quality and architecture tend to change across different training periods.

Epidemiology of injuries in male and female youth football players:A systematic review and meta-analysis

Background:To conduct a systematic review and meta-analysis of epidemiological data of injuries in male and female youth football players.Methods:Searches were performed in MEDLINE/PubMed,Web of Science,Cochrane Library,and SPORTDiscus databases.Studies were considered if they reported injury incidence rate in male and female youth(≤19 years old)football players.Two reviewers(FJRP and ALV)extracted data and assessed trial quality using the Strengthening the Reporting of Observational Studies in Epidemiology(STROBE)statement and the Newcastle Ottawa Scale.The Grading of Recommendations Assessment,Development,and Evaluation approach determined the quality of evidence.Studies were combined using a Poisson random effects regression model.Results:Forty-three studies were included.The overall incidence rate was 5.70 injuries/1000 h in males and 6.77 injuries/1000 h in females.Match injury incidence(14.43 injuries/1000 h in males and 14.97 injuries/1000 h in females)was significantly higher than training injury incidence(2.77 injuries/1000 h in males and 2.62 injuries/1000 h in females).The lower extremity had the highest incidence rate in both sexes.The most common type of injury was muscle/tendon for males and joint/ligament for females.Minimal injuries were the most common in both sexes.The incidence rate of injuries increased with advances in chronological age in males.Elite male players presented higher match injury incidence than sub-elite players.In females,there was a paucity of data for comparison across age groups and levels of play.Conclusion:The high injury incidence rates and sex differences identified for the most common location and type of injury reinforce the need for implementing different targeted injury-risk mitigation strategies in male and female youth football players.

Effects of combined physical and cognitive training on executive function of adolescent shooting athletes:A functional near-infrared spectroscopy study

Individual executive function improvement through physical and cognitive training is a research hotspot in physical education and cognitive science.However,few studies have evaluated whether combined physical and cognitive training(CPCT)has greater benefits for executive function performance and cerebral oxygenation in adolescent athletes than cognitive training alone.This study randomly assigned 33 adolescent shooting athletes to a CPCT(n=17)or computerized cognitive training(CCT,n=16)group and compared their executive function after six weeks of training.All subjects were assessed using the 2-back,task-switching,and Stroop tests before and after training.The prefrontal cortex oxygenated hemoglobin(Oxy-Hb)activation level was monitored while executing the three tasks using functional near-infrared spectroscopy.Our results showed that the CPCT and CCT groups similarly improved their updating function as indicated by the 2-back task accuracy.The CPCT group significantly improved the switching function in the task-switching test accuracy,while the CCT group did not.However,both groups did not improve in behavioral performance as indicated by the inhibition function in the Stroop task.Cerebral oxygenation,indicated by the oxy-Hb activation level in the frontal pole area of the prefrontal lobe,significantly improved in the CPCT group during the three cognitive tasks,whereas the CCT group showed no change.These findings indicated that CPCT endowed greater advantages in task-switching in the behavioral performance of the executive function than CCT.Moreover,CPCT was superior to CCT in increasing task-efficient cerebral oxygenation during the activation of the prefrontal cortex in adolescent shooting athletes.

体育教育领域中的体育素养——挑战与机遇（英文）

自2000年以来,以"体育素养"为主题的文章发表数量显著增加。本文运用归纳法对已发表的以"体育素养"为主题的经过同行评议文章的频次及重要主题进行探索性文献综述。在EBSCO数据库中以"体育素养"和"体育素养和实证"为关键词搜索相关文章。文章检索包括国际体育科学与体育教育理事会(ICSSPE)公告中的"体育素养"特刊。研究围绕3个关键主题:"体育素养"概念的假设前提及其教育作用;体育的发展与体育素养;体育素养的评估。未来研究需检验所提倡的以"体育素养"概念为基础的教学策略是否会导致重新设置有活力的学校课程。现在还有一些批判观点,如将"体育素养"作为理想的基本运动技能和运动员选材的中立化概念。体育素养如何得到社会认可、如何培养体育素养、体育素养与实践如何结合,高等教育在进一步完善这一科学体系中起到至关重要的作用。

Highlights of the 2nd International Symposium on Tribbles and Diseases: tribbles tremble in therapeutics for immunity, metabolism, fundamental cell biology and cancer

The Tribbles(TRIB) family of pseudokinase proteins has been shown to play key roles in cell cycle, metabolic diseases, chronic inflammatory disease, and cancer development. A better understanding of the mechanisms of TRIB pseudokinases could provide new insights for disease development and help promote TRIB proteins as novel therapeutic targets for drug discovery. At the 2 nd International Symposium on Tribbles and Diseases held on May 7–9, 2018 in Beijing, China, a group of leading Tribbles scientists reported their findings and ongoing studies about the effects of the different TRIB proteins in the areas of immunity, metabolism, fundamental cell biology and cancer. Here, we summarize important and insightful overviews from 4 keynote lectures, 13 plenary lectures and 8 short talks that took place during this meeting. These findings may offer new insights for the understanding of the roles of TRIB pseudokinases in the development of various diseases.

早餐、血糖指数和年轻人的健康(英文)

"早餐是一天中最重要的一餐"这句话经常被提及,但它似乎更像是传闻而缺乏事实性的证据,尤其是在涉及儿童和青少年(年轻人)时。然而,现在有大量证据表明,在多样化大样本量年轻人受试者当中,有规律地摄取早餐与营养性强、生活方式佳的健康结果相关,能防止体重增加及营养缺乏,能降低慢性病的风险因素。这一证据已经被评论过,但鲜有人关注早餐构成与健康的关系。越来越多的证据表明,对年轻人而言,某些特定的早餐对健康尤为有利,研究焦点是即食性谷物类早餐和早餐血糖指数。通过逐渐提高血糖控制和饱腹感,将高血糖指数早餐替换为低血糖指数早餐,对于超重的年轻人而言可能更为有利。因此,本文旨在拓展之前关于早餐摄取和健康的文献回顾,进一步研究早餐构成及早餐血糖指数。关于早餐的摄取通常是基于大型横断面研究:而关于早餐血糖指数则主要基于对照型实验研究,试验样本相对较小。有时,需要借鉴成人研究基础的文献来支撑以年轻人为对象的研究成果,或是强调在年轻人群中严重缺乏实际例证的领域。年轻人以及青少年儿童群体越来越不注重早餐,因此有必要制订策略推动年轻人有规律地摄取健康早餐。未来的研究应更加注重早餐构成,探讨控制早餐摄取与健康之间关系的机制,通过与高血糖指数早餐比较来论证规律性摄取低血糖指数早餐的益处。

The Effects of a Four-Week Neuromuscular Training Program on Landing Kinematics in Pre-and Post-Peak Height Velocity Male Athletes

Purpose Neuromuscular training aims to enhance motor skill competency and increase muscle strength.However,the effectiveness of short-duration interventions focused on addressing lower limb injury risk factors in male youth athletes at different stages of maturity remains unknown.Methods Forty-eight young male academy cricket players[pre-peak height velocity(PHV)(n=26)and post-PHV(n=22)]were subdivided into an experimental group(EXP)who completed a 4-week progressive neuromuscular training program and controls(CON)participating in sport training only.Changes in injury risk were examined using the Tuck Jump Assess-ment(TJA)and Landing Error Scoring System(LESS).Results Total LESS score was significantly lower in both EXP maturity groups compared to CON following the 4-week program(10 to 6 and 6 to 4(~20%to 40%))in the pre-and post-PHV EXP groups,respectively.Significant within-group reductions in total LESS score were shown for the pre-PHV EXP group only(P<0.05).Conversely,greater changes in TJA total score were shown in post-PHV(5 to 3;40%)versus pre-PHV EXP(6 to 4.5;26%).Pre-PHV players showed positive changes in individual LESS criteria indicative of frontal plane control but not in knee valgus during the TJA,whereas post-PHV players did improve this criterion.Conclusion This study indicates it is possible to reduce TJA and LESS scores in male youth athletes by performing a 4-week neuromuscular training program,improving landing mechanics and reducing injury risk irrespective of maturity,but their effects are somewhat influenced by stage of maturation and the task performed.

The Influence of Biological Maturity on Dynamic Force-Time Variables and Vaulting Performance in Young Female Gymnasts

Purpose This cross-sectional study investigated dynamic force-time variables and vaulting performance in young female gymnasts of different maturity status.Methods 120 gymnasts aged 5-14 years were sub-divided into maturity groupings using percent of predicted adult height(%PAH)attained.Participants performed three jumping protocols,the squat jump(SJ),countermovement jump(CMJ)and drop jump(DJ),before completing straight jump vaults that were recorded using two-dimensional video.Results Jumping performance improved with biological maturity evidenced by the most mature gymnasts’producing sig-nificantly more absolute force(P<0.05;all d>0.78),impulse(P<0.05;all d>0.75)and power(P<0.05;all d>0.91)than the least mature group,resulting in the greater jump heights(P<0.05;all d>0.70).While,no significant differences were observed in relative peak force across multiple tests,measures of relative peak power did significantly increase with maturity.Based upon regression analyses,maturation was found to influence vertical take-off velocity during vaulting,explaining 41%of the variance in each jumping protocol.Across all tests,the DJ was found to have the highest predictive ability of vaulting vertical take-off velocity,explaining 55%of the total variance.Conclusion Biological maturation impacts jump height and underpinning mechanical variables in young female gymnasts.Vaulting vertical take-off velocity appears to be influenced by maturation and various dynamic force-time variables,par-ticularly those during DJ,which had the highest explained total variance.

Utility of Kinetic and Kinematic Jumping and Landing Variables as Predictors of Injury Risk: A Systematic Review

Purpose Jump-landing assessments provide a means to quantify an individual’s ability to attenuate ground reaction forces,generate lower limb explosive power and maintain joint alignment.In order to identify risk factors that can be targeted through appropriate training interventions,it is necessary to establish which(scalar)objective kinetic,kinematic,and performance measures are most associated with lower-extremity injury.Methods Online searches of MEDLINE,SCOPUS,EBSCOHost,SPORTDiscus and PubMed databases were completed for all articles published before March 2020 in accordance with PRISMA guidelines.Results 40 articles investigating nine jump-landing assessments were included in this review.The 79%of studies using drop jump(n=14)observed an association with future injury,while only 8%of countermovement jump studies(n=13)observed an association with injury risk.The 57%of studies using unilateral assessments found associations with risk of injury(n=14).Studies using performance measures(jump height/distance)as outcome measure were only associated with injury risk in 30%of cases.However,those using kinetic and/or kinematic analyses(knee abduction moment,knee valgus angle,knee separation distance,peak ground reaction force)found associations with injury in 89%of studies.Conclusion The landing element of jump-landing assessments appears to be superior for identifying individuals at greater risk of injury;likely due to a closer representation of the injury mechanism.Consequently,jump-landing assessments that involve attenuation of impact forces such as the drop jump appear most suited for this purpose but should involve assessment of frontal plane knee motion and ground reaction forces.

Change of bio-electric interferential currents of acute fatigue and recovery in male sprinters

We studied the muscle fatigue and recovery of thirty male sprinters(aged 18–22 years)using the Frequency Analysis Method(FAM).The interferential currents(ICs)with different thresholds for sensory,motor and pain responses,the maximal voluntary contraction(MVC),and the amplitude of the surface EMG(aEMG,sEMG)were assessed prior to and immediately after an acute explosive fatigue training session,and during one-week recovery.We found that IC increased on average from 32.38.9 mA to 37.57.5 mA in sensory response at 10 Hz immediately post training(p=0.004)but decreased at 24-hr post training(p=0.008)and returned to pre-levels thereafter.Motor and pain response patterns at 10 Hz were similar(motor:p=0.033 and 0.040;pain:p=0.022 and 0.019,respectively).The change patterns of ICs were similar to but prior to the changes of sEMG.The agreement between IC assessment and amplitude of sEMG(aEMG)/MVC ratio was good(>95%).The present study suggested that the changes in ICs were prior to the changes in both the aEMG and force during fatigue.These changes may reflect the physiological sensory change due to peripheral fatigue.FAM may be useful as an effective early detection and simple tool for monitoring muscle fatigue during training and recovery in athletes.

儿童日常活动水平与心理健康间关系的研究

Aim: To explore the relationship between habitual physical activity and psychological well-being in children. Methods: Seventy children (35 boys, 35 girls), age 10.4 ±0.4 y, wore hip pedometers over a period of 7 d. Well-being was conceptualized as the presence of global self-esteem and the absence of anxiety and depression and assessed with the use of three questionnaires. Results: Correlation analyses revealed that habitual physical activity had a strong association with global self-esteem (r = 0.66), depression (r =-0.60) and anxiety (r =-0.48). However, using partial correlations, the significant relationships were removed for anxiety and depression, but remained for self-esteem (r = 0.36). When groups were created based upon activity level, children achieving > 12 000 stepsday had more positive psychological profiles than children achieving < 9200 stepsday. Conclusion: The results support the findings from previous studies that have explored the relationship between physical activity and well-being, but represent the first to use a mechanical measure of physical activity over a 7-d period to assess the relationships. The actual step counts associated with more positive psychological well-being can be shown to be in line with the recommended guidelines that children accumulate a minimum of 60 min of moderate-intensity activity per day.

The role of glycogen phosphorylase in glycogen biogenesis in skeletal muscle after exercise

Initially it was believed that phosphorylase was responsible for both glycogen breakdown and synthesis in the living cell.The discovery of glycogen synthase and McArdle's disease(lack of phosphorylase activity),together with the high Pi/glucose 1-P ratio in skeletal muscle,demonstrated that glycogen synthesis could not be attributed to reversal of the phosphorylase reaction.Rather,glycogen synthesis was attributable solely to the activity of glycogen synthase,subsequent to the transport of glucose into the cell.However,the well-established observation that phosphorylase was inactivated(i.e.,dephosphorylated)during the initial recovery period after prior exercise,when the rate of glycogen accumulation is highest and independent of insulin,suggested that phosphorylase could play an active role in glycogen accumulation.But the quantitative contribution of phosphorylase inactivation was not established until recently,when studying isolated murine muscle preparations during recovery from repeated contractions at temperatures ranging from 25 to 35C.Thus,in both slow-twitch,oxidative and fast-twitch,glycolytic muscles,inactivation of phosphorylase accounted for 45%–75%of glycogen accumulation during the initial hours of recovery following repeated contractions.Such data indicate that phosphorylase inactivation may be the most important mechanism for glycogen accumulation under defined conditions.These results support the initial belief that phosphorylase plays a quantitative role in glycogen formation in the living cell.However,the mechanism is not via activation of phosphorylase,but rather via inactivation of the enzyme.

Force Generation Profiles of Para-Nordic Sit-Skiers Representing Different Physical Impairments

Purpose To biomechanically profile force generation connected to the complex role of the trunk in double poling in a rep-resentative sample of Para-Nordic sit-skiers.Methods Twelve male World Cup Para-Nordic sit-skiers(sport classes:LW10-12)were skiing on flat snow terrain at submaximal speed of 4.5 m/s(~73% max imum speed).2D video(50 Hz)and pole force analyses(1000 Hz)were performed synchronously,examining angle,force and cycle characteristics to analyse the role of the trunk in generating propulsion.Results LW10-11.5 skiers lost between 21%and 4%propulsive force versus LW12 athletes only due to different geomet-rics of the trunk and pole angle at an equal axial pole force.While LW10-11 skiers indicated trunk extension or position maintenance during pole thrust,LW11.5-12 skiers showed strong trunk flexion combined with smaller pole angles to the ground.Hence,LW11.5-12 skiers could create larger propulsive forces and therefore greater cycle lengths at lower cycle rates at the same speed.Maximum speed increased from LW10 to LW12 and was significantly correlated to trunk flexion range of motion(r=0.63)and cycle length(r=0.59).Trunk flexion ROM showed a significant relationship to the impulse of propulsive force(r=0.63)and pole angle to the ground(r=−0.76)(all P<0.05).Conclusion The impact of impairment on the force production profiles and its physiological-biomechanical consequences need further investigation also in other terrains and at wider spectrums of skiing speeds.The evident problem of low numbers of LW10-11 skiers in World Cup needs creative future solutions for research.

Is it Possible to Protect the Adolescent Brain with Internal Mechanisms from Repetitive Head Impacts:Results from a PhaseⅡSingle Cohort,Longitudinal,Self-Control Study

Purpose To quantify the effects of an externally worn collar device for mitigating the influence of repetitive head impacts on alterations to diffusion tensor imaging(DTI)metrics of white matter.Methods Fifteen female high-school soccer athletes(age:14.00-16.98 yrs)completed pre-and post-season DTI over two consecutive years,including measures of diffusivity,changes in which may be associated with brain dysfunction.The collar was worn during year 1(Yr1)but not during year 2(Yr2).Athlete exposures(AEs)and head impact exposure were recorded over the competitive seasons.Results There were no significant differences in AEs or head impact exposures between Yr1 and Yr2(P>0.05).In Yr2,there was significant pre-to post-season mean diffusivity and/or axial diffusivity reduction in multiple WM regions(cor-rected P<0.05).Pre-to post-season mean diffusivity,axial diffusivity,and radial diffusivity decreases were 3.04%±2.53%,2.97%±2.19%,and 3.37%±3.34%,respectively,significantly greater than pre-to post-season changes in Yr1(mean dif-fusivity:-0.31%±1.78%,P=0.0014;axial diffusivity:-0.02%±2.25%,P=0.0014;radial diffusivity:-0.63%±2.10%,P=0.0030).Conclusions Mild bilateral compression to athletes'internal jugular vein through collar application may have increased intracranial blood volume and spatially redistributed head-impact-derived brain energy absorption.However,future research is needed to elucidate the potential clinical significance of WM changes of various degrees.Clinical trails registration NCT03014492.