The effect of a secondary cognitive task on landing mechanics and jump performance

Anterior cruciate ligament (ACL) injuries commonly occur during jump-landing tasks when individuals’ attention is simultaneously allocated to other objects and tasks. The purpose of the current study was to investigate the effect of allocation of attention imposed by a secondary cognitive task on landing mechanics and jump performance. Thirty-eight recreational athletes performed a jump-landing task in three conditions: no counting, counting backward by 1 s from a randomly given number, and counting backward by 7 s from a randomly given number. Three-dimensional kinematics and ground reaction forces were collected and analysed. Participants demonstrated decreased knee flexion angles at initial contact (p = 0.001) for the counting by 1 s condition compared with the no counting condition. Participants also showed increased peak posterior and vertical ground reaction forces during the first 100 ms of landing (p ≤ 0.023) and decreased jump height (p < 0.001) for the counting by 1 s and counting by 7 s conditions compared with the no counting condition. Imposition of a simultaneous cognitive challenge resulted in landing mechanics associated with increased ACL loading and decreased jump performance. ACL injury risk screening protocols and injury prevention programmes may incorporate cognitive tasks into jump-landing tasks to better simulate sports environments.     

高校开设街舞课程可行性分析

街舞是西方现代社会文化的产物，舞者洒脱宽松的衣着，利落多变的动作，强烈的音乐节奏，营造出震撼的动感，充分展示了现代青少年无拘无束、勇于创新的精神特质。将街舞列入高校体育教学课程有其现实意义。     

基于Haddon模型的高校运动伤害事故预防研究

运用文献资料法、逻辑分析法,结合Haddon模型研究高校运动伤害事故的预防。结果显示:高校运动伤害事故的预防具有较高的可能性和必要性,此类事故的致因可依照Haddon模型从"3阶段、3因素"两个维度进行归纳总结。结合致因分析结果,从"3阶段"出发,提出了相应的预防策略,以期为高校运动伤害事故的预防提供参考。     

Impact of physical activity domains on subsequent physical activity in youth: a 5-year longitudinal study

This study evaluates how domains of physical activity (PA) in youth predict later PA and assesses factors influencing changes in sports participation. Young people from the Children’s Sport Participation and Physical Activity study (n = 873; baseline age 10–18 years; 30.4% male) completed self-report surveys in 2009 and 2014. In a multiple linear regression analysis, participation frequency in club sport (β = 0.18) and extracurricular sport (β = 0.13) significantly predicted PA 5 years later, adjusted for age, sex and urban/rural classification (P < 0.01). Overall, rates of regular (at least once per week) youth sports participation were high (males 79.3–85.5%; females 74.8–83.2%). Uptake and dropout of specific sports varied widely. Despite high levels of migration into and out of Gaelic games, they remained popular at follow-up. Weight training was the only sport that increased in both sexes (P < 0.05). Fitness, friends and enjoyment were top motivations for taking up a new sport. Other commitments, a lack of interest and time were important factors leading to sports dropout. PA promotion strategies should include youth sport, take into consideration what sports are attractive to young people and address reasons for uptake and dropout.     

Effect of a congested match schedule on immune-endocrine responses,technical performance and session-RPE in elite youth soccer players

ABSTRACT

This study investigated the effects of a congested match schedule (7 matches played in 7 days) on steroid hormone concentrations, mucosal immunity, session rating of perceived exertion (S-RPE) and technical performance in 16 elite youth soccer players (14.8 ± 0.4 years; 170.6 ± 9.4 cm; 64.9 ± 7 kg). No change was observed for salivary cortisol concentration across match time points (P = 0.33; effect size [ES] = 0.13–0.48). In contrast, there was a decrease in salivary testosterone and salivary IgA (SIgA) concentrations from the 1st compared with the last time point (P = 0.01 and 0.001, ES = 0.42 and 0.67, respectively). The SIgA concentration varied across time points (P < 0.001) with the highest value observed at the 3rd time point (rest day) (3rd vs all time point; ES = 0.47–0.73). No changes were observed for S-RPE across time points (P > 0.05). A higher number of tackles and interceptions were observed during the 4th match vs 1st and 7th matches (P < 0.001; ES = 2.25 and 1.90, respectively). The present data demonstrate that accumulated fatigue related to participation in a congested match schedule might induce a decrease in testosterone concentration in youth players and negatively affect their mucosal immunity and capacity to perform certain technical actions.     

The Impact of Previous Athleticism on Exercise Habits,Physical Fitness,and Coronary Heart Disease Risk Factors in Middle-Aged Men

Abstract

A longitudinal study was performed to determine differences in physiologic variables, health behaviors, risk factors, or clinical status between former athletes (FA) (N = 345) and nonathletes (NA) (N = 75). The subjects, 420 self-referred white males aged 25-60 years old, were examined for prior athleticism and health. Athleticism was determined through self-reported high school or college athletic history. Baseline physiologic and health behavior characteristics were not different between the two groups. Of those study participants (N = 203 FA, 48 NA) who were sedentary at baseline, 208 (N = 167 FA, 41 NA) voluntarily began an exercise program during the followup period (average followup = 56 months). These numbers correspond to exercise adoption rates of 82 and 85 % for FA and NA respectively, and were not statistically different (95% CI FA = 0.76, 0.88, NA = 0.73, 0.97). Repeated measures analysis of covariance was performed to determine if physiologic responses to adoption were different between FA and NA. No statistically significant difference was found between the two groups, time effects were similar in the two, and no significant interaction of time by group was observed. We conclude that prior athleticism has little apparent impact on health and health behaviors, thus suggesting that contemporaneous exercise has more impact on clinical variables.     

Long-term effects of the 11+ warm-up injury prevention programme on physical performance in adolescent male football players: a cluster-randomised controlled trial

This study examined the long-term effects of the 11+ on physical performance in adolescent male football (soccer) players. Eighty-two 14- to 16-year-old male football players (11+ = 42 players, control = 40 players) participated. Teams were randomised to control (CON) and intervention (INT) groups. INT applied the 11+ injury prevention programme for 30 weeks at least twice a week as a warm-up. CON performed their standard warm-up. Motor performance tests were conducted 1 week prior and 1 week after the competition season. We used magnitude-based inferences and linear mixed-effects models to analyse performance test results. INT showed superior results compared to CON in the vertical jump height 7.5% (95%-CI 4.4%, 10.7%), the Bosco 15-s-jump test 7.2% (95%-CI 2.2%, 12.4%), and the Illinois agility test ?2.6% (95%-CI ?4.1%, ?1.1%). Possibly beneficial effects in favour of INT were found in the 9.1 m sprint test ?3.1% (95%-CI ?6.1%, 0.1%). Possibly harmful effects (i.e. in favour of CON) were observed in the dribbling test 2.8% (95%-CI ?0.8%, 6.4%). The 11+ warm-up programme can improve different performance measures in football players. Coaches might implement additional dribbling drills next to the 11+ to achieve improvements observed in dribbling ability when using a regular warm-up programme.     

The Influence of Feedback on Competence,Motivation, Vitality,and Performance in a Throwing Task

Purpose: The purpose of this work is focused on the study of the effect that feedback has on competence valuation, perceived competence, autonomous motivation, vitality, and performance in a throwing task. Method: Thirty-five college students (26 men and 9 women), without previous experience in the task, participated in this study. The students were randomly assigned to three experimental conditions (positive, negative, and lack of feedback). Results: The results of this study point out that only those who received positive feedback before the handball throwing task, in contrast to those who received negative feedback or did not receive any feedback, showed increased levels of competence valuation (p < .05, Cliff’s delta effect size = ?.30), perceived competence (p < .001, Cliff’s delta effect size = ?.77), and autonomous motivation (p < .05, Cliff’s delta effect size = ?.48). This group also presented higher levels of perceived competence (p < .001, Cliff’s delta effect size = ?.84) and subjective vitality (p < .001, Cliff’s delta effect size = ?.80) than the group who received negative feedback after the throwing task. Those who received positive feedback also showed a higher throwing speed at the end of task than those who received negative feedback (p < 0.001, Cliff’s delta effect size = ?.71) or than those who did not receive any feedback (p < .05, Cliff’s delta effect size = ?.56). Conclusions: Competence valuation, perceived competence, autonomous motivation, subjective vitality, and throwing speed were favorably influenced by positive feedback. These results have important implications for the training style applied by coaches.     

对武术馆校武术套路运动员运动损伤的调查研究

为了解我国青少年武术运动员运动损伤的现状及原因,从武术馆校选取青少年运动员进行问卷调查及访谈,并做统计和分析。结果显示:损伤部位分布在踝、膝、髋等关节,大腿、小腿及腰部肌群等部位。损伤类型以肌肉拉伤和关节损伤的比重较大。损伤原因主要与运动员的身体状况、训练内容、运动负荷、比赛及训练安排有关,并提出了针对性的预防措施。     

Effect of a Marathon Run on Serum Lipoproteins,Creatine Kinase,and Lactate Dehydrogenase in Recreational Runners

Abstract

The objective of this study was to determine the effect of a marathon run on serum lipid and lipoprotein concentrations and serum muscle enzyme activities and follow their recovery after the run. These blood concentrations were measured before, immediately after, and serially after a marathon run in 15 male recreational runners. The triglyceride level was significantly elevated postrace, then fell 30% below baseline 1 day after the run, and returned to baseline after 1 week. Total cholesterol responded less dramatically but with a similar pattern. High-density lipoprotein cholesterol remained significantly elevated and low-density lipoprotein cholesterol was transiently reduced for 3 days after the run. The total cholesterol/high-density cholesterol ratio was significantly lowered for 3 days. Serum lactate dehydrogenase activity significantly doubled postrace and then declined but remained elevated for 2 weeks. Serum creatine kinase activity peaked 24 hr after the run, with a 15-fold rise, and returned to baseline after 1 week. The rise of these enzymes reflects mechanically damaged muscle cells leaking contents into the interstitial fluid. It is concluded that a prolonged strenuous exercise bout in recreational runners, such as a marathon, produces beneficial changes in lipid blood profiles that are significant for only 3 days. However, muscle damage is also evident for 1 week or more from the dramatic and longlasting effect on enzyme levels. Laboratory values for these runners were outside normal ranges for some days after the race.     

Effects of age,maturity and body dimensions on match running performance in highly trained under-15 soccer players

Abstract

The aim of the present study was to compare, in 36 highly trained under-15 soccer players, the respective effects of age, maturity and body dimensions on match running performance. Maximal sprinting (MSS) and aerobic speeds were estimated. Match running performance was analysed with GPS (GPSport, 1 Hz) during 19 international friendly games (n = 115 player-files). Total distance and distance covered >16 km h^–1 (D > 16 km h^?1) were collected. Players advanced in age and/or maturation, or having larger body dimensions presented greater locomotor (Cohen’s d for MSS: 0.5–1.0, likely to almost certain) and match running performances (D > 16 km h^?1: 0.2–0.5, possibly to likely) than their younger, less mature and/or smaller teammates. These age-, maturation- and body size-related differences were of larger magnitude for field test measures versus match running performance. Compared with age and body size (unclear to likely), maturation (likely to almost certainly for all match variables) had the greatest impact on match running performance. The magnitude of the relationships between age, maturation and body dimensions and match running performance were position-dependent. Within a single age-group in the present player sample, maturation had a substantial impact on match running performance, especially in attacking players. Coaches may need to consider players’ maturity status when assessing their on-field playing performance.     

Social physique anxiety experiences in physical activity: a comprehensive synthesis of research studies focused on measurement,theory, and predictors and outcomes

Physical activity (PA) settings such as sport, exercise, and physical education are inherently social and evaluative in nature, with much attention directed at how the body looks and performs. As such, these settings foster a host of positive and negative emotional experiences. Social physique anxiety (SPA) is a commonly studied emotion that emanates from, or motivates, PA behaviors. In this synthesis of the 126 identified research papers focused on SPA and related experiences in sport, exercise, and physical education, we summarize the theoretical roots and measurement of SPA, present research evidence on predictors and outcomes of SPA experiences, explore links between SPA and PA behaviors, and offer insight on the future directions of SPA research. Specifically, researchers in sport and exercise psychology are encouraged to broaden the study of SPA to conduct longitudinal and experimental studies, develop quality intervention strategies aimed at reducing SPA experiences, and expand on the theoretical and operational understandings of SPA experiences across the lifespan.     

功能性力量训练对初中生与高中生功能动作和身体素质影响的对比研究

目的：通过12周的渐进式功能性力量训练干预实验,对初中生与高中生在功能动作和身体素质影响进行对比研究。方法：对266名普通中学生进行了两组四时点的随机对照实验。采用数据分析软件SPSS 24.0比较实验差异。结果：（1）实验组与对照组组间差异显示,实验干预对功能动作质量与身体素质具有显著促进作用,且显著降低了初、高中生多项运动损伤敏感指标;（2）组内差异显示,初中组比高中组总分提升较快、效果较好;初中组的各单项提升相对均衡,高中组则出现肩部灵活性与躯干稳定性改善的局限性;两组在身体素质基础水平与促进程度上有显著差异。结论：功能性力量训练是提高初、高中生功能动作质量并提高身体素质的有效方法,在实施训练时应注意把握其不同特征。     

Effects of a cooling collar on affect,ratings of perceived exertion,and running performance in the heat

Abstract

During prolonged exercise, ratings of perceived exertion (RPE) and affect (pleasure; activation) play an important role in performance, especially in hot conditions. Although various mechanisms have been tried to manage the effects of heat (e.g. cooling jackets), the purpose of the current research was to assess the effect of a cooling collar on RPE, affect, thermal sensation, and running performance in the heat. Participants (n =8) wore a cold collar, uncooled collar or no collar as they completed three 90-min preloaded treadmill time-trials in the heat (30.5±0.1°C), which included 75 min at ～60% [Vdot]O_2max followed by a 15-min time-trial. Affect, RPE, and thermal sensation were measured throughout. Performance during the time-trial was significantly improved in the cold collar compared with the uncooled collar and no-collar trials; however, pleasure and activation ratings were highest for the no-collar trial. Findings suggest that a cooling collar may improve performance, but not necessarily “feel good”. Practically, it seems necessary to ensure sufficient education about the benefits, on balance, of the cold collar, while the performance improvements outweighed the reported discomfort of athletes in this study. In addition, the cold collar may prove quite beneficial for individuals who work in hot climates and or conditions, as it may be effective in minimizing discomfort associated with heat for other groups as well.     

Acute effects of a cluster-set protocol on hormonal,metabolic and performance measures in resistance-trained males

Abstract

Limited research exists on rest-pause or cluster-set (CS) protocols. Acute effects of a traditional set (TS) and CS protocols of resistance exercise on serum growth hormone (GH), cortisol (C), blood lactate (BL), countermovement vertical jump (CMVJ) and standing long jump (SLJ) were compared. Eleven resistance-trained males (22.9±2.6 year; 176.9±10.6 cm; 78.5±1.6 kg; 12.9±3.1% BF) completed one repetition maximum tests for clean pull (CP), back squat (BS) and bench press (BP). Subjects were then randomly assigned to TS or CS protocols for sessions 2 and 3, and performed CP and BS lifts followed by two circuits of three sets of three exercises. GH, C, BL, CMVJ and SLJ were measured pre-exercise (Pre), mid-exercise following completion of CS or TS protocol (Mid), immediately (IP), 15 (15P) and 30 (30P) minutes post-exercise. Repeated measures ANOVAs examined differences in GH, C, BL, CMVJ and SLJ. No differences (p>0.05) existed between protocols for GH and C. GH levels 15P were elevated (p<0.05) above 30P (15.78 + 4.66 vs. 12.10 + 4.66 µg^.L^?1). C levels 30P were elevated (p<0.05) above Pre (716.85 + 102.56 vs. 524.79 + 75.79 nmol^.L^?1). Interaction (p <0.05) existed between protocol and time for BL; mid-BL was lower for CS than TS (7.69±3.73 vs. 12.78±1.90 mmol^.L^?1). Pooled data for CMVJ and SLJ were greater (p <0.05) across the CS protocol. The less metabolically taxing CS protocol resulted in better sustainability of jump measures.     

道次、场地条件和运动水平对速度滑冰女子1000m速度节奏的影响研究

为了探索道次、场地条件和运动水平对速度滑冰女子1000m速度节奏的影响。采用文献资料、访谈和数理统计等研究方法,分析了2012—2013赛季哈尔滨站速度滑冰世界杯和关国速度滑冰世界锦标赛女子1000m前后两次比赛均参加的运动员分段数据,结果认为：（1）速度滑冰女子1000m道次不同造成运动员速度节奏的明显差异,外道速度波动比内道更大;（2）速度滑冰女子l000m场地条件不同,速度节奏存在显著性差异,条件越差的比赛场地,其启动阶段加速节奏越快,600—1000m分段速度节奏越慢;（3）速度滑冰女子1000m高、低水平运动员百分速度节奏存在显著性差异,低水平运动员0—200m启动阶段相对加速节奏更快,600—1000m分段高水平运动员百分速度节奏更快。