Responses to Speed Changes in Coincidence-Anticipation Judgments after Extended Practice

Abstract

Coincidence-anticipation performance has been found to vary with changes in the speed of the task's stimulus. This may be due to bias effects. The present study was designed to investigate the existence of directional error, its persistence after extended practice, and its occurrence upon transfer to new contextual stimuli. Two groups of 20 women athletes each were tested for 270 trials over 3 days on a Bassin anticipation task. One group judged stimulus speeds of 2, 3, and 4 mph and the other group speeds of 2, 4, and 6 mph. Both groups improved during training, but tended to respond late, less accurately, and more variably to the slowest speed. Following a 30-trial warmup on Day 4, the second group transferred to the same speeds given the first group. Following transfer, the Transfer Group demonstrated increased directional bias to the slowest stimulus speed despite having seen this speed throughout training. By the second block of trials following transfer, however, they were performing at an error level similar to that of the Control Group. The present findings are in agreement with those concerning psychophysical judgments, and suggest that skill acquisition may be subject to bias effects if the task involves judgments of varying speeds.     

The effect of exercise intensity on coincidence anticipation performance at different stimulus speeds

Abstract

The aim of this study was to examine the effect of exercise intensity on coincidence anticipation timing [CAT] performance at different stimulus speeds. Fourteen young adults (11 males and 3 females) volunteered to participate in the study following ethical approval. After familiarisation, coincidence anticipation was measured using the Bassin Anticipation Timer under three conditions: rest, moderate-intensity and high-intensity exercise with stimulus speeds of 3, 5 and 8 mph, set using an incremental running protocol until the participants reached a steady state of 70% and 90% of heart rate reserve (HRR), respectively. Results indicated a significant exercise intensity×stimulus speed interaction (p=0.0001) for absolute error (AE). There were no significant differences in AE across exercise intensities at a stimulus speed of 3 mph (p>0.05). AE was poorer during high-intensity exercise (90% HRR) compared to rest (p=0.022), and moderate-intensity (70% HRR) exercise (all, p=0.004 or better) at 5 and 8 mph. Variable error (VE) was similar across exercise intensities at stimulus speeds of both 3 and 5 mph (p>0.05). At a stimulus speed of 8 mph, VE was significantly poorer during high-intensity exercise compared to rest (p=0.006) and moderate-intensity exercise (p=0.008). There were no significant differences for constant error (p>0.05) across exercise intensities or stimulus speeds. High-intensity exercise is associated with poorer CAT performance. However, stimulus speed plays a key role within this association where faster stimulus speeds were associated with a more marked decrease in coincidence anticipation performance.     

Contextual Factors and Age Group Differences in Coincidence-Anticipation Performance

Abstract

Age group differences in the direction of anticipatory motor responses may be attributable to the increased susceptibility of young children to contextual factors. That is, their performances on a given trial may be influenced by the stimulus speed presented in the previous trial. Mixed-sex groups of 8–9 year-olds and adults were given 3 blocks of 18 coincidence-anticipation trials each in a counterbalanced design. One block contained stimulus speeds of 1, 3, or 5 MPH, another speeds of 3, 5, or 7 MPH, and a third speeds of 5, 7, or 9 MPH, so that the 5 MPH speed was common to all blocks. An age group by sex by testing order by trial block ANOVA of constant error on the 5 MPH trials indicated that trial block was a significant factor within an age group by block interaction. Mean scores showed that the children responded very early in the 5–7–9 MPH block to the 5 MPH stimuli while the adults did not. Testing order was also a significant factor: subjects in the 1–3–5, 5–7–9, 3–5–7 MPH order performed with significantly greater directional error. While the later finding may indicate contextual factors influenced performance, there is no strong evidence that contextual factors differentially affected the age groups.     

Analysis of speed accuracy using video analysis software

Determining an athlete’s speed from broadcast video is a common practice in sport. Many software packages that perform data extraction from video files are expensive; however, open source software is also available, but lacks published validation for speed measurements. The purpose of this research was to examine the error of speed measurements extracted from video during an ice hockey skating exercise using open source software. The subject completed four exercises, at two speeds recorded by broadcast cameras set at five angles. The speeds from the broadcast cameras were compared to speeds calculated from a high-speed camera placed orthogonally to the exercise. Speeds from the broadcast cameras correlated well with the high-speed video for motion more than 12 m away from the broadcast camera. When comparing all the measured speeds, no significant difference was found between the speeds calculated by the high-speed camera (slow: 4.46 m/s ± 0.2; fast: 7.2 m/s ± 0.7) and the speed calculated from the broadcast cameras (slow: 4.50 m/s ± 0.4; fast: 7.34 m/s ± 0.6) (p > 0.05). The open source method was found to be less accurate when the athlete was close to (within 12 m of camera position) or moving directly toward the broadcast cameras.     

Retroactive interference effects of mentally imagined movement speed

In two retroactive interference experiments, we assessed the effect of mentally imagined movement speed on subsequent motor performance. All participants performed a sequential motor action at three speeds during a baseline test and a retention test. During the retention interval of Experiment 1, the participants (n = 50) physically performed the action at a slow speed, physically performed it at a fast speed, imagined it at a slow speed, imagined it at a fast speed, or performed a no-practice control task. In Experiment 2, the participants (n = 24) imagined the movement, overtly vocalized words, or both, all at a slow speed. The results revealed that the speed of the imagined motor action affected the speed of subsequent performance in the retention test and that imagery and physical practice were functionally equivalent. The results are consistent with Lang's bio-informational theory.     

Retroactive interference effects of mentally imagined movement speed

In two retroactive interference experiments, we assessed the effect of mentally imagined movement speed on subsequent motor performance. All participants performed a sequential motor action at three speeds during a baseline test and a retention test. During the retention interval of Experiment 1, the participants (n = 50) physically performed the action at a slow speed, physically performed it at a fast speed, imagined it at a slow speed, imagined it at a fast speed, or performed a no-practice control task. In Experiment 2, the participants (n = 24) imagined the movement, overtly vocalized words, or both, all at a slow speed. The results revealed that the speed of the imagined motor action affected the speed of subsequent performance in the retention test and that imagery and physical practice were functionally equivalent. The results are consistent with Lang's bio-informational theory.     

Pretask Speed Training and Movement Complexity

Abstract

The purpose of the study was to determine the effects of pretask speed training and movement complexity on skill acquisition using the rotary pursuit. The study was a two-part investigation utilizing subjects from two different schools. The data from each school were analyzed separately with slight procedural differences made in the second investigation. The first study included 72 third graders; 90 third and fourth graders were in the second investigation. Both studies used a pretask training period of three days and a testing period of three additional days. A criterion speed of 50 rpm was used in the first study; 40 rpm was used in the second study. Three pretask training groups were used: one trained at the criterion speed and the other two using a gradual build-up of speeds with one being closer to the criterion than the other. The complexity dimension was studied by using a circle, square, or triangle top plate on the rotary pursuit. Both investigations used a 3 × 3 × 3 factorial ANOVA with repeated measures on the last factor (days). Although differences were found in performance over the test days according to the type of pretask training, the days × speed interaction indicated that by the fourth and fifth day the only group performing significantly poorer (p < .05) was the group trained at a very slow speed in relationship to the criterion speed. The complexity × speed interaction was not significant (p > .05) indicating no differential effects for these two factors.     

儿少速滑运动员系统训练的方法与手段

依据速滑运动项目特点和优秀全能速滑运动员成长规律,密切结合儿少速滑运动员身心特点,对儿少速滑运动员进行系统的全面培养,打好其身体素质、运动素质、技术素质和心理素质的基础。提出了儿少速滑运动员有氧耐力训练、力量训练、速度训练、基本技术和心理训练等系统训练方法和手段要点,对于儿少速滑教练员树立系统训练的理念,掌握系统训练的方法和手段,具有指导意义和借鉴作用。     

Discrimination of Visual Linear Velocities

Abstract

The purpose of the present study was to determine velocity discrimination characteristics of subjects in a difference threshold paradigm. After recruitment, 180 male and female subjects were randomly assigned to 1 of 6 groups differentiated by the length of the stimulus runway and the subjects' orientation to the stimulus. Stimulus velocities were presented on a modified Bassin Anticipation Timer with presentation rate controlled by a programmed timer. The criterion velocities were 134.11, 268.22 and 402.33, cm/sec with variable velocities ranging 44.7 cm/sec above and below the criterion in 8.94 cm/sec increments. The method of constant stimuli was used with 198 trial pairs presented (constant 7 second stimulus presentation interval). The results indicated that the discrimination of horizontal linear velocity follows a prothetic continuum. That is, the just noticeable difference increased in proportion to the increase in the criterion velocity. In addition, the subjects' orientation to the stimulus and the viewing distance (length of runway) seemed to play little or no role in the discrimination process.     

Validity of the iPhone M7 motion co-processor as a pedometer for able-bodied ambulation

Physical activity benefits for disease prevention are well-established. Smartphones offer a convenient platform for community-based step count estimation to monitor and encourage physical activity. Accuracy is dependent on hardware–software platforms, creating a recurring challenge for validation, but the Apple iPhone® M7 motion co-processor provides a standardised method that helps address this issue. Validity of the M7 to record step count for level-ground, able-bodied walking at three self-selected speeds, and agreement with the StepWatch^TM was assessed. Steps were measured concurrently with the iPhone® (custom application to extract step count), StepWatch^TM and manual count. Agreement between iPhone® and manual/StepWatch^TM count was estimated through Pearson correlation and Bland-Altman analyses. Data from 20 participants suggested that iPhone® step count correlations with manual and StepWatch^TM were strong for customary (1.3 ± 0.1 m/s) and fast (1.8 ± 0.2 m/s) speeds, but weak for the slow (1.0 ± 0.1 m/s) speed. Mean absolute error (manual–iPhone®) was 21%, 8% and 4% for the slow, customary and fast speeds, respectively. The M7 accurately records step count during customary and fast walking speeds, but is prone to considerable inaccuracies at slow speeds which has important implications for certain patient groups. The iPhone® may be a suitable alternative to the StepWatch^TM for only faster walking speeds.     

Tennis forehand kinematics change as post-impact ball speed is altered

Peak joint angles and joint angular velocities were evaluated for varying speed forehands in an attempt to better understand what kinematic variables are most closely related to increases in post-impact ball velocity above 50% of maximal effort. High-speed video was used to measure three-dimensional motion for 12 highly skilled tennis players who performed forehands at three different post-impact ball speeds: fast (42.7 +/- 3.8 m/s), medium (32.1 +/- 2.9 m/s), and slow (21.4 +/- 2.0 m/s). Several dominant-side peak joint angles (prior to ball impact) increased as post-impact ball speed increased from slow to fast: wrist extension (16%), trunk rotation (28%), hip flexion (38%), knee flexion (27%), and dorsiflexion (5%). Between the aforementioned peak joint angles and ball impact, dominant-side peak angular velocities increased as ball speed increased from slow to fast: peak wrist flexion (118%), elbow flexion (176%), trunk rotation (99%), hip extension (143%), knee extension (56%), and plantarflexion (87%). Most kinematic variables changed as forehand ball speed changed; however, some variables changed more than others, indicating that range of motion and angular velocity for some joints may be more closely related to post-impact ball speed than for other joints.     

Body Composition and Anthropometric Correlates of Isokinetic Leg Extension Strength of Young Adult Males

Abstract

The present study examined the relative importance of body size and composition as determinants of individual differences in isokinetic leg extensor strength in young adult males performing at slow, moderate, and fast speeds. The subjects were 31 males between the ages of 19 and 29 years, who were not participating in weight training programs. Low to moderate correlations were found between isokinetic strength and body size or body composition measurements. At each speed, similar proportions of the variance in peak torque values were accounted for by lean body weight (23-30%) and thigh volume (20-37%). However, body weight, often suggested as the best reference standard for equalizing strength scores, also accounted for only 13-24% of the variance in peak torque values at each of the speeds tested. The moderate correlations reported in this study do not support the use of body size and composition measurements as a means of adjusting strength values.     

篮球防守中需正确掌握的4种辩证关系

篮球防守战术运用辩证法，在训练和比赛中正确把握刚与柔、紧与松、快与慢、扩大与缩小的关系，以利于全面提高防守技战术水平。     

The role of path length- and speed-related factors for the enhancement of section performance in alpine giant slalom

Knowing how to enhance alpine skiing performance is essential for effective coaching. The purpose of this study was to explore the role of path length- and speed-related factors for performance enhancement, while skiing on a homogeneously set/constantly inclined giant slalom course section (average gate distance: 27?m; offset: 8?m; slope inclination: 26°). During a video-based three-dimensional kinematic field-experiment, the data of six athletes who skied a two-gate section on four different types of skis were collected. The performance parameter analysed was section time. The performance predictors analysed were centre of mass (CoM), path length and the change in specific mechanical energy per entrance speed along the analysed section. Furthermore, since the current study examined alpine skiing performance within short sections, the skier’s entrance speed was also considered. Classified as a high-performance and a low-performance group based on section time, slow and fast trials significantly differed in CoM path length, the change in specific mechanical energy per entrance speed and entrance speed. The entrance speed of all trials analysed ranged between 15.25 and 17.66?m/s. In trials with both high and low entrance speed, the change in specific mechanical energy per entrance speed was found to be more relevant for the prediction of section time than CoM path length. However, further studies should investigate whether such a prioritization can be unrestrictedly generalized to other situations, such as entrance speeds, course sets, slope inclinations and competition disciplines different to those assessed in the current study.     

论竞走运动的技术特点及其训练

竞走运动技术结构一是“腾空”，二是“直腿”。这也是技术训练的重点和难点。把技术训练与能力训练结合起来，乃之竞走训练的升华。     

The effects of static stretching on speed and agility: One or multiple repetition protocols?

Although static stretching (SS) is utilized during warm-up before training and competition, the results about its effects on performance remain controversial. We examined whether performing a stretch of short-to-moderate duration (<60 sec) in a single repetition produces a similar or different effect on speed and agility performance from the effect which is produced while performing the same stretch in multiple repetitions of the same total duration. According to a repeated measurement design, 40 trained males were randomly assigned to either (1) a single repetition group or (2) a multiple repetition group. The participants in each group performed five trials: a control trial (no stretches were performed) and four experimental trials of SS protocols consisting of five exercises performed at either 20 sec (2 × 10 in the second group), 30 sec (3 × 10 in the second group), 40 sec (4 × 10 in the second group) or 60 sec (6 × 10 in the second group) of total duration. A two-way repeated measures analysis of variance showed that the participants in both group improved their speed performance in response to the 20-sec trial, whereas agility remained unaffected. Data analysis also revealed that the repetition number did not affect speed and agility performance. These data suggest that SS of short duration (<30 sec) may actually improve acute speed performance, whereas SS of moderate duration may not hamper speed and agility performance. Moreover, the effects of SS protocols are related to the total duration of each exercise and not to the number of repetitions in which each exercise is performed.     

Subject Gender,Knowledge of Results,and Receptor Anticipation

The effect of subject gender and knowledge of results (KR) on receptor anticipation (Poulton, 1957) was investigated. Twenty trials were given in which subjects (N = 80) attempted to time a preferred-hand button press response coincident with the lighting of the last of a series of runway lights illuminating in a pattern of apparent motion of 9 mph. Half of the subjects received quantitative KR after each trial and half performed without KR. Each group contained 20 males and 20 females. Mean absolute error, mean algebraic error, and variable error were calculated for each subject on the block of trials 2 to 5 and on the three subsequent 5-trial blocks. The dependent measures were then analyzed by means of separate 2 × 2 × 4 (Gender × KR × Blocks) ANOVAs with repeated measures on the last factor. The results indicated that the receptor anticipation of males was more accurate and less variable than that of females, and KR did not influence the accuracy of anticipations but was associated with higher intravariability. Sociocultural and physiological explanations for sex differences in receptor anticipation are discussed.     

现代短跑技术训练特征分析

从生理学、生物力学、训练学理论出发对现代短跑(以短跑典型项目100米跑为主)技术特征进行分析,提出了现代短跑技术教学训练渐趋的四大特征,以期对改变短跑技术教学训练滞后于飞速发展的现代短跑运动实践的状况和提高我国短跑运动训练水平有所裨益。     

北京2008奥运会中国女子中长跑队展望

运用文献资料法对当今世界女子中长跑的比赛特点和训练发展趋势进行对比分析,认为当今女子中长跑的比赛是两头快中间稍慢的速度节奏特点,训练发展趋势是以速度为核心的大强度训练。我国女子中长跑运动员在比赛速度节奏的把握和最后的冲刺速度能力上与国外运动员有一定的差距,与此同时也为我国女子中长跑今后的训练提出了合理性建议。     

自由式滑雪女子空中技巧优秀运动员下肢肌力与静态平衡能力特征

采用等速测试和平衡测试方法,对我国优秀自由式滑雪空中技巧女子运动员的髋关节、膝关节屈肌力和伸肌力以及4种站姿下的静态平衡能力特征进行研究。结果表明髋关节右侧屈伸肌力、屈伸肌力比、平均功率值稍大于左侧屈肌力量,膝关节伸肌左、右侧单位体重峰力矩和左、右侧平均功率4个指标数值均大于屈肌,在60°/s（慢速）和240°/s（快速）不同的测试速度下,单位体重屈伸峰力矩、屈伸平均功率、屈伸肌力、平均功率随着测试速度的增加出现了显著性差异;正常双脚站立的平衡性大于单脚站立的平衡性。建议合理控制体重及均衡的训练肌肉力量,在适度提高运动速度的情况下,加强下肢伸肌力量的训练,为运动员进行针对性的力量训练、训练后肌肉效果的评价、运动员选材提供科学依据及有价值的理论参考。