Evaluation of a lower-body compression garment

The aims of this study were to determine how custom-fit compression shorts affect athletic performance and to examine the mechanical properties of the shorts. Ten male and 10 female track athletes on a university's nationally competitive track team, specializing in sprint or jump events, participated in the study. Testing utilized the compression shorts with loose-fitting gym shorts as the control garment. Several significant effects were revealed for the custom-fit compressive garment. Although 60 m sprint time was not affected, hip flexion angle was reduced. Skin temperature increased more and at a faster rate during a warm-up protocol. Muscle oscillation was decreased during vertical jump landing. Countermovement vertical jump height increased when the participants were wearing the custom-fit compression garment. In materials testing, the elasticity of the compressive garment provides increased flexion and extension torque at the end range of extension and flexion, respectively, and may assist the hamstrings in controlling the leg at the end of the swing phase in sprinting. The compressive garment significantly reduced impact force by 27% compared with American football pants alone. Through various mechanisms, these findings may translate into an effect on athletic performance and a reduction in injuries.     

An examination of psychosocial variables moderating the relationship between life stress and injury time-loss among athletes of a high standard

Based on Williams and Andersen's model of stress and athletic injury, six psychosocial variables were assessed as possible moderators of the relationship between life stress and injury among 121 athletes (65 males, 56 females) competing in a variety of sports at state, national or international level. No significant effects of the sex of the participants were evident. Correlational analyses revealed moderator effects of several variables. Specifically, dispositional optimism and hardiness were related to decreased injury time-loss in athletes when positive life change increased, and global self-esteem was associated with decreased injury time-loss when both negative life change and total life change increased. The results indicate that athletes with more optimism, hardiness or global self-esteem may cope more effectively with life change stress, resulting in reduced injury vulnerability and recovery rates.     

专项运动员半月板损伤的生理学及生物力学分析与预防对策

方法：采用问卷调查法、数理统计法和文献资料法,对陕西省优秀男子运动员膝关节半月板运动损伤情况进行研究。结果：在接触性运动项目中,关月板损伤率较大,且与训练年限有正相关。其损伤的原因主要是准备活动不充分、膝关节力量不足、训练方法不当、身体疲劳及长期局部劳损等。结论：根据半月板损伤的机制与病因,结合生物力和运动解剖学知识,提出科学的预防措施,为康复治疗和运动训练提供理论参考。     

若干力学参数对跳远成绩的影响

本文建立了考虑空气阻力时，跳远运动员空中运动的微分方程，根据量阶比较，求得该方程的适定解。与以往所发表的不考虑空气阻力时的远度公式比较，定量讨论风速，空气密度，重力加速度等力学参数对跳远成绩的影响量值。     

对中外男子优秀十项全能运动员运动成绩之差异分析

通过查阅并整理中外男子优秀十项全能运动员10年来的运动成绩,笔者运用文献资料法、比较研究法、数理统计法,对运动成绩进行对比研究,结果表明我国男子十项全能运动整体水平和个体最好成绩与世界存在一定的差距,根据我国运动员的身体素质和运动技术水平的实际情况,提高我国全能运动整体水平在1 500m、400m和撑杆跳高单项上应加强训练,以提高其耐力素质.全国个人全能记录保持者龚国华在110m栏、100m和跳远单项上应加强速度素质训练,以提高个人运动速度.     

Confounding compression: the effects of posture,sizing and garment type on measured interface pressure in sports compression clothing

The purpose of this investigation was to measure the interface pressure exerted by lower body sports compression garments, in order to assess the effect of garment type, size and posture in athletes. Twelve national-level boxers were fitted with sports compression garments (tights and leggings), each in three different sizes (undersized, recommended size and oversized). Interface pressure was assessed across six landmarks on the lower limb (ranging from medial malleolus to upper thigh) as athletes assumed sitting, standing and supine postures. Sports compression leggings exerted a significantly higher mean pressure than sports compression tights (P < 0.001). Oversized tights applied significantly less pressure than manufacturer-recommended size or undersized tights (P < 0.001), yet no significant differences were apparent between different-sized leggings. Standing posture resulted in significantly higher mean pressure application than a seated posture for both tights and leggings (P < 0.001 and P = 0.002, respectively). Pressure was different across landmarks, with analyses revealing a pressure profile that was neither strictly graduated nor progressive in nature. The pressure applied by sports compression garments is significantly affected by garment type, size and posture assumed by the wearer.     

Activity profile and physiological demands of top-class soccer assistant refereeing in relation to training status

To determine the movement patterns and physiological demands of top-class soccer assistant referees, we performed computerized time-motion analysis and measured heart rate and blood lactate concentration in 15 assistant referees during 22 competitive matches in the top Danish league. To relate match performance to the physical capability of the assistant referees, they performed a 3 2 30 m sprint protocol before and after matches and a laboratory treadmill test within 3 weeks of the games. The mean total distance covered by the top-class assistant referees was 7.28 (range 5.78-8.16) km, of which 1.15 (0.86-1.44) km was high-intensity running and 1.16 (0.12-2.34) km was sideways running. The amount of high-intensity running during a game was correlated with performance of repeated sprints (r = 0.80, P ? 0.05). Mean heart rate was 137 (117-159) beats · min^-1 , corresponding to 73% (60-88%) of maximal heart rate and 65% (53-80%) of maximal oxygen uptake. Blood lactate concentration was 4.7 (1.6-11.0) and 4.8 (1.1-13.7) mmol · l -1 after the first and second half, respectively. Sprinting performance was poorer (P ? 0.05) after than before the games. The peak distance to the offside line was greater (P ? 0.05) in the second than the first half (7 - 1 vs 5 - 0 m). Our results show that: (1) top-class assistant soccer refereeing is characterized by brief intense bouts of forward and sideways running interspersed with long periods of low activity; (2) top-class soccer assistant referees have moderate aerobic energy production during games with episodes of high aerobic and anaerobic energy turnover; (3) assistant referees' performance of repeated sprints correlates with the amount of high-intensity running performed in a game; and (4) sprint performance decreases towards the end of a game, which appears to affect assistant referees' ability to keep up with play.     

Athletic goal achievement: A critical antecedent of event satisfaction,re-participation intention,and future exercise intention in participant sport events

The purpose of this study is to develop a comprehensive understanding of consumer experiences in participant sport events. The authors explored two traditionally prominent components (i.e., service quality and perceived economic value) and one emerging factor (i.e., athletic goal achievement) of consumer experiences at participant sport events. The authors examined the effects of these three factors on re-participation intention and the effect of athletic goal achievement on future exercise intention. Results of moderated serial mediation analyses based on data from a sample of marathon runners (N = 3186), all three factors exerted significant effects on re-participation intention. In particular, athletic goal achievement was positively associated with re-participation intention and future exercise intention through the serial mediation of performance satisfaction and overall event satisfaction. However, the moderating effects of athletic goal importance on the serial indirect relationship between athletic goal achievement and two outcome variables (i.e., re-participation intention and future exercise intention) were not significant. The findings of this study offer participant sport service providers with insights to manage participants’ athletic performance, service quality, and perceived economic value for better consumer experiences. Such efforts should result in higher participant satisfaction, better retention rates, and a higher post-event physical activity level.     

ACTN3 R577X genotype and athletic performance in a large cohort of Japanese athletes

Aim: Recent meta-analyses of the literature confirmed the association between the RR+RX genotype of the ACTN3 R577X polymorphism and elite sprint/power athletic status in Europeans but not in Asians and Africans, while the association between the R577X genotype and elite endurance athlete status is less convincing. The aim of the present study was to investigate the association between the ACTN3 R577X genotype and elite athlete status in a large Asian (Japanese) cohort of track and field athletes. Methods: One-thousand fifty-seven Japanese track and field athletes (627 sprint/power athletes and 430 endurance athletes) and 810 Japanese controls were genotyped for the ACTN3 R577X polymorphism (rs1815739) by using the TaqMan® SNP Genotyping Assay. Results: Elite sprint/power athletes had a higher frequency of the RR+RX genotype than the controls (OR: 1.59, 95% CI: 1.16–2.18; P?=?.003). A significant linear correlation was found between the RR?+?RX genotype and athlete status (i.e. regional?P?=?.001 for trend) and long-distance runners (regional: 65%, national: 72%, international: 82%; P?=?.030 for trend). Conclusions: The data obtained for this large Asian (Japanese) cohort of track and field athletes served to confirm the association between the RR?+?RX genotype of the ACTN3 R577X polymorphism and elite sprint/power athlete status and also the association between the ACTN3 RR?+?RX genotype and long-distance running athletic status.     

我国青年女子篮球运动员体能评价指标体系及评价标准的研究

运用献资料、理论研究、数据统计、测试等方法，研究制定了我国青年女子篮球运动员体能评价指标体系及标准。评价体系由一级指标和二级指标组成。一级指标主要包括机能类、运动素质类、技能体能类、心理类指标。评价体系和评价标准的制定，对我国青年女子篮球运动员技能水平评价具有实用价值。     

Effects of a phase change cooling garment during exercise in the heat

The purpose of our study was to examine the physiological, perceptual, and performance effects of wearing a phase change cooling garment (CG) during an interval exercise routine in the heat. Sixteen male participants (age 23?±?3 years, ht 1.76?±?0.11?m; wt 78.5?±?11.2?kg; body fat 15.2?±?5.8%) completed two trials (one with phase change inserts, CG, and one control without inserts) consisting of two submaximal exercise portions separated by 5-minute seated rest, and a final maximal effort performance bout. Each submaximal bout involved 30?seconds or 1?minute of muscular endurance and agility exercises and 5?minutes of treadmill jogging and step-ups. The performance bout included 30?seconds or 1?minute of muscular endurance and agility exercises, with participants completing as many repetitions as possible, followed by a 15-minute recovery (active and passive). Rectal temperature (T_re) and heart rate were not different between trials, however change in T_re from baseline was improved during 10 and 15 minutes of recovery with the CG (P?<?.05). Mean skin temperature was lower using the CG vs control throughout the trial (P?<?.05). Thermal sensation was lower when using the CG compared to control (P?<?.001). There were no differences in any outcomes of the performance exercises (P?>?.05). These findings indicate that the continuous use of a CG during an interval style workout in the heat provides improvements in thermal sensation, however, only minimal thermophysiological benefits, and no performance augmentation.     

Effect of different velocity loss thresholds during a power-oriented resistance training program on the mechanical capacities of lower-body muscles

This study compared the effects of two velocity loss thresholds during a power-oriented resistance training program on the mechanical capacities of lower-body muscles. Twenty men were counterbalanced in two groups (VL10 and VL20) based on their maximum power capacity. Both groups used the same exercises, relative intensity and repetition volume, only differing in the velocity loss threshold of each set (VL10: 10% vs. VL20: 20%). Pre- and post-training assessments included an incremental loading test and a 15-m linear sprint to assess the force- and load-velocity relationships and athletic performance variables, respectively. No significant between-group differences (P > 0.05) were observed for the force-velocity relationship parameters (ES range = 0.15–0.42), the MPV attained against different external loads (ES range = 0.02–0.18) or the 15-m sprint time (ES = 0.09). A high between-participants variability was reported for the number of repetitions completed in each training set (CV = 30.3% for VL10 and 29.4% for VL20). These results suggest that both velocity loss thresholds induce similar changes on the lower-body function. The high and variable number of repetitions completed may compromise the velocity-based approach for prescribing and monitoring the repetition volume during a power-oriented resistance training program conducted with the countermovement jump exercise.     

对12、13届亚运会田径运动水平的量化评价与比较研究

本文运用达标类体育项目运动水平百分制评定法，以12、13届亚运会当年的世界田径最好成绩为标准，对12、13届亚运会田径运动水平进行了定量分析与比较研究。结果表现：与第12届亚运会相比，第13届亚运会田径运动水平男子呈停滞状态，女子呈下降趋势。     

采用李雅普诺夫稳定性理论进行大学生体育素质稳定性评估

针对大学生体育素质的稳定性评估,确定了评估内容,给出评估指标及其测度方法来表征相应内容。随后,基于李雅普诺夫稳定性理论,建立了大学生体育素质的动态方程,进行评估实验说明方法有效性。     

Returning to competition after a serious injury: The role of self-determination

Abstract

We tested hypotheses grounded in self-determination theory regarding athletes' cognitive appraisals and emotional reactions when returning to competition following a serious injury. Professional male athletes (N = 225) competing in the Australian Football League were presented with return-to-competition scenarios that varied with respect to: (1) degree of self-determination and (2) salience of re-injury concern. Significant MANOVA main effects were observed for the degree of self-determination on both primary appraisals and emotional responses as well as for the salience of re-injury concern on emotional response. Follow-up ANOVA polynomial trend analyses provided support for the hypothesized trends for greater self-determination in the return to sport to result in more positive appraisals and affect. Findings support self-determination theory contentions and research indicating the psychological benefits of increased self-determination.     

Effects of inspiratory muscle training in professional women football players: a randomized sham-controlled trial

This study was conducted to determine the effects of inspiratory muscle training (IMT) on respiratory and peripheral muscles oxygenation during a maximal exercise tolerance test and on repeated-sprint ability (RSA) performance in professional women football players. Eighteen athletes were randomly assigned to one of the following groups: SHAM (n = 8) or IMT (n = 10). After a maximal incremental exercise test, all participants performed (on a different day) a time-to-exhaustion (Tlim) test. Peripheral and respiratory muscles oxygenation by near-infrared spectroscopy, breath-by-breath ventilatory and metabolic variables, and blood lactate concentration were measured. The RSA test was performed on a grass field. After a 6 week intervention, all athletes were reevaluated. Both groups showed increases in inspiratory muscles strength, exercise tolerance and RSA performance, however only the IMT group presented lower deoxyhemoglobin and total hemoglobin blood concentrations on intercostal muscles concomitantly to an increased oxyhemoglobin and total hemoglobin blood concentrations on vastus lateralis muscle during Tlim. In conclusion, these results may indicate the potential role of IMT to attenuate inspiratory muscles metaboreflex and consequently improve oxygen and blood supply to limb muscles during high-intensity exercise, with a potential impact on inspiratory muscle strength, exercise tolerance and sprints performance in professional women football players.     

Generations: Academic and Athletic Integration of a Southern PWI Basketball Program

Purpose: The purposes of this study were to: (a) analyze the insights and experiences of the 1st African American student-athlete (in basketball) at a prominent predominantly White institution in the Deep South as well as the later insights and experiences of his sons at the same university; and (b) to present a counterstory to the dominant historical rendering of the Civil Rights Movement, the integration of athletics, and the experiences and outcomes of contemporary African American athletes. Method: Using qualitative critical race methodology, investigators conducted and analyzed interviews with the 1st African American to play basketball at a prominent university located in the Deep South and his 2 sons who attended the same university a generation later. Results: Using the lens of critical race theory, the themes conceived from the analysis were the counterstory of agency, counterstorytelling stereotypes, and the salience of everyday racism. Conclusion: Racism is still existent within society, even within college athletics. The holistic success of African American athletes in college is dependent upon their ability to navigate overt and covert racial climates.     

Statistical modelling of knee valgus during a continuous jump test

Landing with the knee in a valgus position is recognized as a risk factor for anterior cruciate ligament (ACL) injury. Using linear and non-linear regression analyses, the purpose of this study was to examine the correlation between two-dimensional (2D) knee valgus and three-dimensional (3D) knee kinematics measured during a jump landing task. Twenty-eight female collegiate athletes participated. All participants were required to perform a continuous jump test. The average maximum angles of abduction and internal tibial rotation during landing were measured using the Point Cluster Technique. Average peak knee valgus angle was measured using a 2D approach. Linear and non-linear regression analyses between 2D valgus and 3D knee abduction, and between 2D valgus and 3D internal tibial rotation, were performed. The R ² value between 2D valgus and 3D knee abduction was significantly different from zero and had a moderate correlation for all models, whereas the R ² value between 2D valgus and 3D internal tibial rotation was not significantly different from zero. The 2D approach could be used to screen a specific group of individuals for risk of ACL injury; however, using frontal plane 2D analysis of valgus motion to evaluate internal tibial rotation is not advised.     

Validation of a videogrammetry technique for analysing American football helmet kinematics

ABSTRACT

Professional American football games are recorded in digital video with multiple cameras, often at high resolution and high frame rates. The purpose of this study was to evaluate the accuracy of a videogrammetry technique to calculate translational and rotational helmet velocity before, during and after a helmet impact. In total, 10 football impacts were staged in a National Football League (NFL) stadium by propelling helmeted 50th percentile male crash test dummies into each other or the ground at speeds and orientations representative of concussive impacts for NFL players. The tests were recorded by experienced sports film crews to obtain video coverage and quality typically available for NFL games. A videogrammetry procedure was used to track the position and rotation of the helmet throughout the relevant time interval of the head impact. Compared with rigidly mounted retroreflective marker three dimensional (3-D) motion tracking that was concurrently collected in the experiments, videogrammetry accurately calculated changes in translational and rotational velocity of the helmet using high frame rate (two cameras at 240 Hz) video (7% and 15% error, respectively). Low frame rate (2 cameras at 60 Hz) video was adequate for calculating pre-impact translational velocity but not for calculating the translational or rotational velocity change of the helmet during impact.