Technique analysis in elite athletes using principal component analysis

The aim of this study was to advance current movement analysis methodology to enable a technique analysis in sports facilitating (1) concurrent comparison of the techniques between several athletes; (2) identification of potentially beneficial technique modifications and (3) a visual representation of the findings for feedback to the athletes. Six elite cross-country skiers, three world cup winners and three national elite, roller ski skated using the V2 technique on a treadmill while their movement patterns were recorded using 41 reflective markers. A principal component analysis performed on the marker positions resulted in multi-segmental “principal” movement components (PMs). A novel normalisation facilitated comparability of the PMs between athletes. Additionally, centre of mass (COM) trajectories were modelled. We found correlations between the athletes’ performance levels (judged from race points) and specific features in the PMs and in the COM trajectories. Plausible links between COM trajectories and PMs were observed, suggesting that better performing skiers exhibited a different, possibly more efficient use of their body mass for propulsion. The analysis presented in the current study revealed specific technique features that appeared to relate to the skiers’ performance levels. How changing these features would affect an individual athlete’s technique was visualised with animated stick figures.     

优秀排球运动员比赛效能的评定

介绍运用效能评分法对排球运动员在比赛中进行技术评定的方法。此评定方法既简单易学、易用,又能比较客观地衡量每一个运动员在比赛中技术水平发挥的状况和比赛中的作用,为赛后进行总结和下一步的训练提供可靠的资料     

Success in elite cycling: A prospective and retrospective analysis of race results

The development of peak performances is a main research focus in sports science. It is unclear how many former top junior athletes achieve success in the elite class later. The aim of the present study was to examine the careers of athletes who participated in major junior or adult/elite cycling events using prospective and retrospective analysis of competition results. The official results of major junior (age < or = 18 years) and elite (age > 18 years) cycling races from 1980 to 2004 were analysed. Age-related aspects, career lengths, and success were compared between riders who presented results in both junior and elite races (JUNIOR ELITE) and riders who had no junior race results (ELITE ONLY). Altogether, 27,454 results of 8004 athletes from 108 countries were collected. We found that 29.4% of the elite athletes had participated in junior World Championships, and that 34% of the participants in junior World Championships later participated in major elite competitions. JUNIOR ELITE athletes are significantly more successful in several cycling disciplines and have their first and last elite result at a younger age than ELITE ONLY athletes. No difference was found in career lengths. The data presented here emphasize the importance of long-term training programmes in the development of peak performance in cycling.     

Success in elite cycling: A prospective and retrospective analysis of race results

Abstract

The development of peak performances is a main research focus in sports science. It is unclear how many former top junior athletes achieve success in the elite class later. The aim of the present study was to examine the careers of athletes who participated in major junior or adult/elite cycling events using prospective and retrospective analysis of competition results. The official results of major junior (age ≤ 18 years) and elite (age > 18 years) cycling races from 1980 to 2004 were analysed. Age-related aspects, career lengths, and success were compared between riders who presented results in both junior and elite races (JUNIOR ELITE) and riders who had no junior race results (ELITE ONLY). Altogether, 27,454 results of 8004 athletes from 108 countries were collected. We found that 29.4% of the elite athletes had participated in junior World Championships, and that 34% of the participants in junior World Championships later participated in major elite competitions. JUNIOR ELITE athletes are significantly more successful in several cycling disciplines and have their first and last elite result at a younger age than ELITE ONLY athletes. No difference was found in career lengths. The data presented here emphasize the importance of long-term training programmes in the development of peak performance in cycling.     

Assessment of hydration status by urinary analysis of elite junior taekwon-do athletes in preparing for competition

The aim of this study was to assess over time the hydration status of taekwon-do athletes during a preparatory camp. Measures of urine osmolality, conductivity, specific gravity and colour were made on the first urine sample passed by the participants (n = 32) in the morning before breakfast. The urinary measurements were made on samples collected at the beginning of the camp, 5 days later and one day before competition. Body mass was also measured at the same instants. Body mass (mean +/- s) was essentially the same on each of the measurement days (62.6 +/- 12.2, 62.7 +/- 12.3 and 62.2 +/- 12.6 kg, respectively). Mean urine osmolality at the beginning of the camp was relatively high (998 +/- 171 mOsmol . kg-1), suggesting that a significant number of the athletes were already hypohydrated. However, no significant differences were detected in urine osmolality at the three time points during the study. There were no significant differences in any of the four methods of urine analysis during the study (P > 0.05). The average values for all samples were 989 +/- 205 mOsmol . kg-1 for osmolality, 25.5 +/- 6.7 mS . cm-1 for conductivity, 1.017 +/- 0.010 g . cm-3 for specific gravity and 4 +/- 1 arbitrary units for colour. Correlation analysis between the different methods suggested moderately good agreement (correlation coefficient = 0.5-0.7) between all four measurement techniques (P < 0.01). The coefficients of variation for these techniques were relatively low (CV = 11.8 - 35.0%). The results of this study suggest that some of the taekwon-do athletes were slightly hypohydrated in the morning on each of the test days, but there was no evidence to suggest that most of the athletes further restricted their fluid intake to make weight. In addition, it appears that each of the four methods used gave essentially the same estimate of hydration status of these athletes.     

Assessment of hydration status by urinary analysis of elite junior taekwon-do athletes in preparing for competition

Abstract

The aim of this study was to assess over time the hydration status of taekwon-do athletes during a preparatory camp. Measures of urine osmolality, conductivity, specific gravity and colour were made on the first urine sample passed by the participants (n = 32) in the morning before breakfast. The urinary measurements were made on samples collected at the beginning of the camp, 5 days later and one day before competition. Body mass was also measured at the same instants. Body mass (mean ± s) was essentially the same on each of the measurement days (62.6 ± 12.2, 62.7 ± 12.3 and 62.2 ± 12.6 kg, respectively). Mean urine osmolality at the beginning of the camp was relatively high (998 ± 171 mOsmol · kg^?1), suggesting that a significant number of the athletes were already hypohydrated. However, no significant differences were detected in urine osmolality at the three time points during the study. There were no significant differences in any of the four methods of urine analysis during the study (P > 0.05). The average values for all samples were 989 ± 205 mOsmol · kg^?1 for osmolality, 25.5 ± 6.7 mS · cm^?1 for conductivity, 1.017 ± 0.010 g · cm^?3 for specific gravity and 4 ± 1 arbitrary units for colour. Correlation analysis between the different methods suggested moderately good agreement (correlation coefficient = 0.5–0.7) between all four measurement techniques (P < 0.01). The coefficients of variation for these techniques were relatively low (CV = 11.8 – 35.0%). The results of this study suggest that some of the taekwon-do athletes were slightly hypohydrated in the morning on each of the test days, but there was no evidence to suggest that most of the athletes further restricted their fluid intake to make weight. In addition, it appears that each of the four methods used gave essentially the same estimate of hydration status of these athletes.     

世界女子体操优秀全能选手的单项竞争倾向特征

采用文献资料法、数理统计法和逻辑推理法,系统分析了当伞世界女子体操优秀全能选手的四个单项竞争倾向特征.结果表明:在2005年FIG"不封顶"新规则下,由2001年体操规则催生的单项奖牌扩大化趋势,在2005-2008奥运周期内相对萎缩.未来大赛具备"顶尖项目"的优秀全能型选手,将可获得较大的奖牌竞争空间.全能选手的单项竞争力度将增大,但奖牌争夺将主要集中在高低杠、平衡木、自由体操三个项目上,而尤以高低杠争夺力度最大,其次是平衡木和自由体操.     

优秀体操运动员比赛心理稳定性的调控方法

比赛心理稳定性对于运动员比赛成绩的发挥起着非同寻常的作用,该心理能力的强弱,有运动员先天个性品质的原因,也有运动员自身比赛经验的积累和后天训练等方面的原因。比赛心理稳定性在比赛过程中的调控固然非常重要,但调控的效果还是取决于平时训练的功夫。     

Effects of competition on the sleep patterns of elite rugby union players

Abstract

No published research has assessed sleep patterns of elite rugby union players following match-play. The present study examined sleep patterns of professional rugby union players, prior and post-match-play, to assess the influence of competition. Twenty-eight male rugby union players (24.4?±?2.9 years, 103.9?±?12.2?kg) competed in one of four competitive home matches. Player's sleep behaviours were monitored continuously using an Actiwatch^® from two days before the match, until three days post-match. Repeated measures of analysis of variance (ANOVA) showed significant differences across the time points measured for time to bed (F?=?26.425, η² ?=?0.495, p < .001), get up time (F?=?21.175, η²?=?0.440, p?<?.001), time spent in bed (F?=?10.669, η²?=?0.283, p?<?.001), time asleep (F?=?8.752, η²?=?0.245, p?<?.001) and percentage of time moving (F?=?4.602, η²?=?0.146 p?<?.05). Most notable, post hocs revealed a significant increase for time in bed the night before the match (p?<?.01; 95% CI?=?0?:?10–1?:?28?h; 9.7?±?13.5%) compared with the reference night sleep. Furthermore, time asleep significantly decreased post-match (p?<?.05; 95% CI?=??0:03 to ?1:59?h; ?19.5?±?19.8%) compared to two nights pre-match. Across all time points, sleep latency and efficiency for most players were considered abnormal compared to that expected in normal populations. The results demonstrate that sleep that is deprived post-match may have detrimental effects on the recovery process.     

Sprint start kinematics during competition in elite and world-class male and female sprinters

The start kinematics has been reported to differ between male and female sprinters. This study aimed to determine whether kinematic differences between the sexes are attributable to an effect of sex per se, or rather to the absolute performance level of the sprinters, quantified by the 100-m time. A total of 20 sprinters (10 M, 10 F), including world-class and elite athletes, were assessed. Start phases from the “set” position to the first two steps were analysed. Linear regression analyses showed a few significant differences between sexes when taking into account the effect of performance level: M had shorter pushing phase duration, higher horizontal velocity at block clearing, and shorter contact times of the first two steps. Conversely, the performance level affected most of the examined parameters: faster sprinters showed the centre of mass (CM) closer to the ground and a more flexed front knee in the “set” position, longer pushing phase duration, lower vertical velocity of the CM at block clearing, and longer contact times and shorter flight times in the first two steps. These findings suggest that the start kinematics is only partially affected by the sex of sprinters, whereas a bigger role is played by their performance level.     

A comparison of match demands between elite and semi-elite rugby league competition

We assessed the effectiveness of two generalized visual training programmes in enhancing visual and motor performance for racquet sports. Forty young participants were assigned equally to groups undertaking visual training using Revien and Gabor’s Sports Vision programme (Group 1), visual training using Revien’s Eyerobics (Group 2), a placebo condition involving reading (Group 3) and a control condition involving physical practice only (Group 4). Measures of basic visual function and of sport-specific motor performance were obtained from all participants before and immediately after a 4-week training period. Significant pre- to post-training differences were evident on some of the measures; however, these were not group-dependent. Contrary to the claims made by proponents of generalized visual training, we found no evidence that the visual training programmes led to improvements in either vision or motor performance above and beyond those resulting simply from test familiarity.     

Sleep and stress hormone responses to training and competition in elite female athletes

Stress hormone and sleep differences in a competition versus training setting are yet to be evaluated in elite female team-sport athletes. The aim of the current study was to evaluate salivary cortisol and perceptual stress markers during competition and training and to determine the subsequent effects on sleep indices in elite female athletes. Ten elite female netball athletes (mean?±?SD; age: 23?±?6 years) had their sleep monitored on three occasions; following one netball competition match (MATCH), one netball match simulation session (TRAIN), and one rest day (CONTROL). Perceived stress values and salivary cortisol were collected immediately pre- (17:15 pm) and post-session (19:30 pm), and at 22:00 pm. Sleep monitoring was performed using wrist actigraphy assessing total time in bed, total sleep time (TST), efficiency (SE%), latency, sleep onset time and wake time. Cortisol levels were significantly higher (p?p?p?相似文献   

山东优秀女子400 m跑运动员赛前训练负荷分析

对山东优秀女子400 m跑运动员备战第十届全运会的跟踪调研和大量的数据统计结果表明:赛前训练负荷的安排要以自身的生理、生化指标为依据,根据女子的身体机能特征科学安排量和强度;在备战第十届全运会中,山东队专门设计了"加量加强度"和"降量降强度"的赛前训练方案,并取得了非常优异的成绩.这一赛前训练方法要比传统的"小量大强度"的赛前训练更为科学合理,为赛前训练注入了新的内容.     

Anthropometric profiles are associated with long-term career attainment in elite junior rowers: A retrospective analysis covering 23 years

Introduction: Successful rowers are heavier and taller than their opponents, but the effect of these variables on long-term career attainment in juniors has not been examined. We therefore analysed this in a large sample of elite German junior rowers. Methods: Former German Junior National Team rowers (N?=?910; 399 females) were grouped according to their highest career attainment, i.e., participation in U19-, U23-, Senior World Championships or Olympic Games (OG). Differences in standing height (SH), body mass (BM) and body mass index (BMI) between groups were analysed using unpaired t-tests and magnitude-based inferences (MBI), effects of anthropometrics on career attainment were analysed with a proportional odds model. Interquartile ranges of the OG group were used to define normative data ranges. Results: SH and BMI very likely differed between career attainment in females. The same was found in males for SH and BM. BM (odds ratio (OR)?=?0.958, P?=?.0171) and BMI (OR?=?0.787, P?=?.0004) had a significant effect on career attainment in females as SH (OR?=?1.072, P?=?.0002) and BM (OR?=?1.049, P?=?.0004) had in males. Interquartile ranges of SH and BM were 178–184?cm and 68–73?kg in females, 190–196?cm and 84–93?kg in males. Conclusion: Anthropometric characteristics at junior age affect long-term career attainment even within elite U19 National Team rowers, underlining the relevance of anthropometric assessments and their consideration for talent identification and development programmes in rowing. We provide evidence-based normative data that rule out an anthropometric limitation of junior rowers for career progression to Olympic level.     

Physiological responses and performance in a simulated trampoline gymnastics competition in elite male gymnasts

Abstract

Physiological responses and performance were examined during and after a simulated trampoline competition (STC). Fifteen elite trampoline gymnasts participated, of which eight completed two routines (EX1 and EX2) and a competition final (EX3). Trampoline-specific activities were quantified by video-analysis. Countermovement jump (CMJ) and 20 maximal trampoline jump (20-MTJ) performances were assessed. Heart rate (HR) and quadriceps muscle temperature (T_m) were recorded and venous blood was drawn. A total of 252 ± 16 jumps were performed during the STC. CMJ performance declined (P < 0.05) by 3.8, 5.2 and 4.2% after EX1, EX2 and EX3, respectively, and was 4.8% lower (P < 0.05) than baseline 24 h post-competition. 20-MTJ flight time was ~1% shorter (P < 0.05) for jump 1–10 after EX2 and 24 h post STC. T_m increased (P < 0.05) to ~39°C after the warm-up, but declined (P < 0.05) 1.0 and 0.6ºC before EX2 and EX3, respectively. Peak HR was 95–97% HR_max during EX1-3. Peak blood lactate, plasma K⁺ and NH₃ were 6.5 ± 0.5, 6.0 ± 0.2 mmol · l^?1 and 92 ± 10 µmol · l^?1, respectively. Plasma CK increased (P < 0.05) by ~50 and 65% 0 and 24 h after STC. In conclusion, a trampoline gymnastic competition includes a high number of repeated explosive and energy demanding jumps, which impairs jump performance during and 24 h post-competition.     

优秀气手枪射击运动员临赛前脑电图变化的特征研究

目的:探讨我国优秀气手枪射击运动员赛前一天和临赛前脑电图变化的特征.方法:应用便携式无需屏蔽的脑电图测试系统,对参加好运北京气手枪射击比赛的我国优秀运动员的赛前一天和临赛前脑电图进行测试分析,比较安静状态和表象状态的变化.结果:赛前一天表象和安静状态相比,整个脑区α波能量百分比降低,β波能量百分比上升;临赛前比较该变化的趋势不明显;赛前一天的平均唤醒水平为17.91%±12.67%,临赛前平均为12.99%±11.65%(P＜0.01);赛前一天的疲劳参数表象状态较安静状态低(P＜0.01),应激参数表象状态高于安静状态(P＜0.05);临赛前的疲劳参数的表象和安静状态相比无差异(P＞0.05),应激参数表象状态小于安静状态(P＜0.01).结论:优秀气手枪射击运动员临赛前大脑平均唤醒水平低于赛前一天,大脑左右半球的协同能力提高,脑电图能在一定程度上反映赛前运动员的紧张度和疲劳度.     

A comparison of the activity demands of elite and sub-elite Australian men's basketball competition

The purpose of the study was to describe the differences in the activity demands of sub-elite and elite Australian men's basketball competition. Ten elite (age 28.3 ± 4.9 years, mass 97.0 ± 13.9 kg, height 197.4 ± 8.3 cm) and 12 sub-elite (age 26.1 ± 5.3 years, mass 85.9 ± 13.2 kg, height 191.4 ± 7.6 cm) Australian basketball players participated in the study. Player activity was analysed using video-based time-motion analysis across multiple in-season matches. Customized analytical software was used to calculate player activity into frequencies, mean and total durations (s), and mean and total distances (m) for standing/walking, jogging, running, sprinting, low shuffling, high shuffling, and dribbling movements. Only movement frequency was calculated for jumping and upper body activity. Multivariate analysis of variance revealed that elite players performed significantly more total movement changes (P <0.001), and experienced greater activity workloads while jogging (P <0.01) and running (P <0.002). In contrast, sub-elite players performed significantly more standing/walking (P <0.023) and sprinting (P <0.003) activities. These data suggest that elite basketball competition requires a greater intermittent workload and more sustained activity demands, whereas sub-elite competition may involve greater bursts of activity and longer recovery periods. These differences are likely to reflect variations in player skill and fitness, as well as playing structure between playing standards.     

A notational analysis of elite tennis strategy

A notational analysis of singles events at all four Grand Slam tournaments between 1997 and 1999 was conducted to determine the influence of the sex of the player and court surface on elite tennis strategy. Rallies of 7.1 ± 2.0 s in women's singles were significantly longer than those in men's singles (5.2 ± 1.8 s P < 0.001). Rallies of 6.3 ± 1.8 s at the Australian Open, 7.7 ± 1.7 s at the French Open, 4.3 ± 1.6 s at Wimbledon and 5.8 ± 1.9 s at the US Open were recorded. Rallies were significantly longer at the French Open than at any other tournament ( P < 0.05) and significantly shorter at Wimbledon than at any other tournament ( P < 0.05). In women's singles, 52.8 ± 12.4% of points were baseline rallies, significantly more than in men's singles (28.6 ± 19% P < 0.001). The proportion of baseline rallies played at the French Open (51.9 ± 14.2% of points) was significantly greater than at the Australian Open (46.6 ± 12.5%), Wimbledon (19.7 ± 19.4%) and the US Open (35.4 ± 19.5% P < 0.05). The results show that both the sex of the player and surface of the court have a significant influence on the nature of singles tennis at Grand Slam tournaments.