Controlled exertion of force by developmentally delayed young men and women

Present purposes were to examine the characteristics of controlled force exertion in 28 developmentally delayed young people (14 men, 14 women), and sex differences compared to 28 normal young students (14 men, 14 women). The subjects matched their submaximal grip strength to changing demand values displayed in a bar chart on the display of a personal computer. The total sum of the differences between the demand value and grip exertion value for 25 sec. was used as an evaluation parameter for the test. The controlled force exertion was significantly poorer for he developmentally delayed group than for controls, and there were large individual differences. The developmentally delayed men scored poorer than women in coordination. Like the controls, the means between trials did not decrease significantly. For these developmentally delayed subjects, performance did not improve after only a few trials. The controlled force-exertion test is useful as a voluntary movement-function test for developmentally delayed subjects.     

The influence of color and demand characteristics on muscle strength and affective ratings of the environment

Demand characteristics may influence claims that the color pink inhibits muscle strength whereas blue increases muscle strength. In Experiment 1, undergraduates (N = 59; 30 women, 29 men) were told either that the experimenters thought pink would increase and blue decrease strength or that blue would increase muscle strength and pink decrease muscle strength. A hand dynamometer assessed grip strength as subjects stared at each of 8 differently colored panels. Results indicated that men viewing the pink or orange panels had higher grip strength under pink-strengthen than under pink-weaken instructions. The reverse relationship was found for men viewing a green panel. For women, the pink-weaken instructions resulted in a higher grip strength than did the pink-strengthen instructions, regardless of actual color present. In Experiment 2, women in a no-instruction control condition had lower grip strength than women given the pink-weaken instructions. For men, the control (no-instruction) condition resulted in higher grip strength than the pink-weaken condition. Results of both studies suggest that men followed overt demand characteristics but that women reacted with increased intensity to any suggestion that a stereotypically feminine pink is associated with weakness.     

The Influence of Color and Demand Characteristics on Muscle Strength and Affective Ratings of the Environment

Demand characteristics may influence claims that the color pink inhibits muscle strength whereas blue increases muscle strength. In Experiment 1, undergraduates (N = 59; 30 women, 29 men) were told either that the experimenters thought pink would increase and blue decrease strength or that blue would increase muscle strength and pink decrease muscle strength. A hand dynamometer assessed grip strength as subjects stared at each of 8 differently colored panels. Results indicated that men viewing the pink or orange panels had higher grip strength under pink-strengthen than under pink-weaken instructions. The reverse relationship was found for men viewing a green panel. For women, the pink-weaken instructions resulted in a higher grip strength than did the pink-strengthen instructions, regardless of actual color present. In Experiment 2, women in a no-instruction control condition had lower grip strength than women given the pink-weaken instructions. For men, the control (no-instruction) condition resulted in higher grip strength than the pink-weaken condition. Results of both studies suggest that men followed overt demand characteristics but that women reacted with increased intensity to any suggestion that a stereotypically feminine pink is associated with weakness.     

Gender differences in reaction to psychological pressure: evidence from tennis players

Using data on about 35,000 professional tennis matches, we test whether men and women react differently to psychological pressure arising from the outcomes of sequential stages in a competition. We show that, with respect to men, women losing the first set are much more likely to play poorly the second set. This suggests that women are more discouraged when facing the pressure of falling behind and receiving negative feedback. The gender differential is stronger in high-stake matches. On the other hand, when players are tied in the third set we do not find any gender difference in players’ reactions suggesting that women are as able as men to handle pressure if they do not lag behind. These results are robust controlling for measures of abilities and fitness of players, such as players’ rankings, players’ ex-ante winning probability, players’ rest, monetary prizes, players’ and tournaments’ fixed effects.     

Field dependence-independence in complex motor skills

This study analyzed the relationship between field dependence-independence and complex motor skills. According to the requirements of each sporting activity, subjects' motor system can be mainly controlled through exteroceptive or proprioceptive information. Sport performances require the athlete to disembed himself, other players, or the ball from the background, and decision-making appears to require cognitive restructuring. 26 athletes (13 men and 13 women) involved in acrobatic sports (gymnastics, trampoline, half-pipe snowboard, synchronized 3-m springboard, acrobatic rock, skateboard, and free skating) and 26 athletes (13 men and 13 women) involved in individual racket sports (tennis and table-tennis) completed the Group Embedded Figures Test. Participants (at least 10 years of practice) were from 16 to 35 years of age (M=22.0, SD=3.1). No significant difference among athletes on scores for field dependence-independence was evidenced given this expertise, sex, or age. Significantly higher scores were obtained by athletes in acrobatic sports, indicating that they tended to be predominately more field-independent whereas the lower scores were obtained by tennis and table-tennis players.     

Effects of Fatigue and Laterality on Fractionated Reaction Time

Surface EMG enabled fractionation of a simple hand grip total reaction time into peripheral and central processing components (motor time and premotor time, respectively). Changes in reaction time components were investigated in 12 female intercollegiate swimmers (bilateral athletes) and 12 female intercollegiate tennis players (unilateral athletes) following a 48% strength decrement induced by serial maximal voluntary isometric contractions (5 sec in duration). Despite significantly greater strength in the dominant arm than in the nondominant arm, there was no difference in fatigue effects between arms. Fatigue increased the premotor component of reaction time significantly, and indirectly the total reaction time, but the motor time remained essentially constant regardless of the type of previous athletic training. This indicated that fatigue impaired central nervous system or myoneural-junction operations rather than the intramuscular ability to initiate force.     

Effects of fatigue and laterality on fractionated reaction time

Surface EMG enabled fractionation of a simple hand grip total reaction time into peripheral and central processing components (motor time and premotor time respectively). Changes in reaction time components were investigated in 12 female intercollegiate swimmers (bilateral athletes) and 12 female intercollegiate tennis players (unilateral athletes) following a 48% strength decrement induced by serial maximal voluntary isometric contractions (5 sec in duration). Despite significantly greater strength in the dominant arm than in the nondominant arm, there was no difference in fatigue effects between arms. Fatigue increased the premotor component of reaction time significantly, and indirectly the total reaction time, but the motor time remained essentially constant regardless of the type of previous athletic training. This indicated that fatigue impaired central nervous system or myoneural-junction operations rather than the intramuscular ability to initiate force.     

Grip strength of Texas Special Olympians

Little is known about the physical fitness parameters of individuals who participate in the Special Olympics. The purpose of this study was to assess the grip strength of 104 Special Olympians participating in the winter Olympic Games. Men were significantly stronger than women across age groups 20 to 59 yr. Women's right hands were stronger than their left, while the opposite was true for men, despite the fact that 78.8% of the subjects reported right hand dominance. Mean right and left grip strengths were 25-40% less than the 1985 normative data of Mathiowetz, et al. by age groups. Special Olympian men and women have grip strengths comparable to elderly people rather than age-matched men and women.     

Association of birthdate with success of nationally ranked junior tennis players in the United States

The objective was to assess the effect of birthdate on successful performance in tennis by junior tennis players in the United States and to address the question of whether "birthdate effect" persisted with ongoing age toward adulthood. The national rankings and birthdates of junior tennis players in each age division were obtained from the United States Tennis Association. The number of male and female junior tennis players ranked within the top 100 in their respective age divisions with birthdates in the first half of the year were counted and compared with the number of junior athletes born in the second half of the year. A significant chi squared for birthdate by success in tennis was present in the 14 years and under and 16 years and under age divisions for boys. This effect was less for older ages. Among girls, the effect of birthdate on tennis ranking was not significant in any age group. Among male junior tennis players in the 14 years and under and 16 years and under age divisions, athletes born in the first half of the year had an advantage over those born in the second half, but not for girls.     

Expert-novice differences in cognitive and execution skills during tennis competition

This study deals with decision and execution behavior of tennis players during competition. The study is based on the expert-novice paradigm and aims to identify differences between both groups in the decision-making and execution variables in serve and shot actions in tennis. Six expert players (elite Spanish tennis players) and six novice players (grade school tennis players) took part in this study. To carry out this study, the observation protocol defined by McPherson and Thomas in 1989, in which control, decision-making and execution variables were included, was used, where it was applied to the performance of the tennis player in a real match situation. In the analysis, significant differences between experts and novices in decision-making and execution variables are found wherein it can be observed that experts display a greater ability to make the appropriate decisions, selecting the most tactical responses to put pressure on the opponent. Expert tennis players were also able to carry out forceful executions to their opponent with greater efficiency, making the opponent's response to a large extent more difficult. These findings are in accordance with those of McPherson and colleagues.     

Mood states of professional female tennis players

To develop a psychological profile of professional female athletes, specifically of elite tennis players, 16 professional female tennis players from five countries were given the Profile of Mood States to measure six mood states: tension, depression, anger, vigor, fatigue, and confusion. When age was controlled in the design, older female athletes exhibited the "iceberg profile," i.e., they scored higher on the vigor mood state and lower on all other mood states than college-age women. Younger athletes scored like college-age women. These results only partially support the 1987 work of Morgan, O'Connor, Sparling, and Pate.     

Coordination of Grip Configurations as a Function of Force Output

In this investigation, the authors examined the coordination and control of force production by the digits of the hand as a function of criterion force level and grip configuration. Each adult participant (N = 6: 3 men and 3 women) was required to place the thumb and a finger (or fingers) upon load cells that were fixed to a grasping apparatus that was clamped to a table. In the task, participants had to match a criterion continuous constant total force level displayed on a computer screen. There were 10 trials at each grip configuration and criterion force level combination on each of 3 consecutive days. The results showed that (a) different grip configurations minimized error at each force level; (b) there was a specific digit pairing within a given grip configuration that produced the highest correlation of force output; (c) the correlation between the force output of digits generally increased at higher force levels; (d) error was reduced at each force level and grip configuration over the practice period; and (e) the organization of the force output of each digit varied as a function of digit, force level, grip configuration, and practice. The findings are consistent with the hypothesis that coordination of the digits in prehension is reflective of an adaptive, task-specific solution that is modified with practice.     

长期高策略性技能训练对运动员大脑白质结构的影响：一项DTI研究

目前关于运动员经验优势的脑机制还存在争议, 尤其对于涉及较多认知过程参与的高策略性技能项目运动员, 其大脑白质结构可塑性变化还需进一步探究。研究横向对比了乒乓球运动员和非运动员大脑白质纤维束的弥散张量成像数据。结果发现, 相比于非运动员, 乒乓球运动员在连接背侧和腹侧通路脑区的双侧皮质脊髓束、左侧上纵束、左侧下纵束和双侧额枕下束的各向异性值(FA)更大, 进一步分析发现, 部分腹侧通路白质纤维束FA增加的原因是径向扩散系数(RD)下降。研究结果支持了动作双通路模型。提示经过长期高策略性技能训练, 乒乓球运动员在背侧和腹侧通路上的白质纤维束结构完整性增强。     

Importance of head movements in gaze tracking during table tennis forehand stroke

The purpose of this study was to clarify the properties of gaze and head movements during forehand stroke in table tennis. Collegiate table tennis players (n = 12) conducted forehand strokes toward a ball launched by a skilled experimenter. A total of ten trials were conducted for the experimental task. Horizontal and vertical movements of the ball, gaze, head and eye were analyzed from the image recorded by an eye tracking device. The results showed that participants did not always keep their gaze and head position on the ball throughout the entire ball path. Our results indicate that table tennis players tend to gaze at the ball in the initial ball-tracking phase. Furthermore, there was a significant negative correlation between eye and head position especially in the vertical direction. This result suggests that horizontal VOR is suppressed more than vertical VOR in ball-tracking during table tennis forehand stroke. Finally, multiple regression analysis showed that the effect of head position to gaze position was significantly higher than that of eye position. This result indicates that gaze position during forehand stroke could be associated with head position rather than eye position. Taken together, head movements may play an important role in maintaining the ball in a constant egocentric direction in table tennis forehand stroke.     

Finger tapping: effects of trials and sessions

18 normal, self-reported dextral subjects (9 men, 9 women) were assessed with a Halstead Manual Finger Tapping device, with 10 trials per hand for 10 consecutive wk. The test-retest reliability of the 10-trial average between the 10 sessions averaged .94 for men and .86 for women, for both preferred and nonpreferred hands. There were no statistically significant effects of increases in performance over sessions or effects of fatigue over trials for either sex or hand. There were, however, significant increases over trials for men for both preferred and nonpreferred hands.     

Quantifying synergies in two-versus-one situations in team sports: An example from Rugby Union

Collective behaviors in team sports result in players forming interpersonal synergies that contribute to performance goals. Because of the huge amount of variables that continuously constrain players’ behavior during a game, the way that these synergies are formed remain unclear. Our aim was to quantify interpersonal synergies in the team sport of Rugby Union. For that purpose we used the Uncontrolled Manifold Hypothesis (UCM) to identify interpersonal synergies that are formed between ball carrier and support player in two-versus-one situations in Rugby Union. The inter-player angle close to the moment of the pass was used as a performance variable and players running lines velocities as task-relevant elements. Interpersonal synergies (UCM values above 1) were found in 19 out of 55 trials under analysis, which means that on 34% of the trials, the players’ running line velocities contribute to stabilizing the inter-player angle close the moment of the pass. The strength of the synergy fluctuates over time indicating the existence of a location effect during attack phases in Rugby Union. UCM analysis shows considerable promise as a performance analysis tool in team sports to discriminate between skilled sub-groups of players.     

Physical fitness and self-reported physical exercise among college men and women in 1987 and 1997.

The study examined the relations of self-reported physical activity levels and physical fitness scores for two samples of college students assessed in 1987 (n = 261) and in 1997 (n = 243). Significantly greater exercise was reported by the 1997 women than the 1987 women; amount of exercise reported by men did not differ. For both samples, greater exercise was associated with increased fitness for women and men as assessed by the Hall 1986 Physical Fitness Test Profile, comprised of measures on body fat composition; grip strength; muscle endurance, flexibility, resting heart rate; systolic and diastolic blood pressures; and aerobic power. For the 1987 sample men were more fit than women. For the 1997 sample, women were more fit than men. The 1997 women were more fit than the 1987 women; there was no difference on overall fitness measures of the two samples of men.     

Visual search,anticipation, and reactive comparisons between highly-skilled and beginning tennis players

Abstract

Simulated tennis playing situations were created for the laboratory testing of visual search patterns, anticipation, reactions, and movements to compare male and female high-level and beginning players. Of particular interest was the degree to which each measure would differentiate the groups. Participants were highly-rated university players (N-30) and students enrolled in a beginning tennis class (N = 30). Under one testing condition, visual search patterns were recorded as they viewed filmed opponents serve (60 trials) and hit ground strokes (60 trials). Also recorded was anticipation accuracy and speed of the intended type and location of serves and the intended placement of ground strokes. In other testing, execution of a split step was followed by moving rapidly to the comet location for a simulated stroke in response to a series of light cues. Reaction and movement times were recorded. Discrimination analysis revealed that experts and beginners were most differentiated due to fixations on certain cues and predicting ball direction. As to visual search analysis of fixation duration for nine possible areas during the serves, only the head area was significant. Beginners directed more time toward the head region than did the highly skilled. Experts and novices had similar visual patterns with respect to ground strokes, and a few differences existed within the two female groups, in the two male groups. as well as between males and females. Anticipation measures for the serve indicated that experts were faster and more accurate than beginners, and males were faster than females. Ground stroke data revealed that the highly-skilled were faster and more accurate than novices. Finally, the simulated split-step data showed that reaction times and movement times were faster for the experts versus the beginners, and males were quicker in movement times than females.     

Field dependence and physical ability.

Field-dependence scores of professional dancers, highly skilled performers in tennis, soccer, cricket and track and field athletics, medium-ability level players in the same four sports and a group of non-game players were measured using a rod and frame test. Results showed that highly skilled tennis players were significantly more field-dependent than top-class track and field athletes and medium-ability level tennis players.     

Individual differences in distancing responses to women on a photo choice task

A heterogeneous sample of adult women and men responded to a Photo Choice Task (PCT) in which they were asked to make 24 choices between two persons for a hypothetical interaction; eight of the choices were between a woman and a man. Participants also responded to a measure of adherence to Sex Role Stereotypes and to a measure of Adversarial Sexual Beliefs. On the eight choices between a woman and a man on the PCT, men over 30 and younger than 30 chose women below chance level. Women over 30 made other-gender and same-gender choices that did not differ from chance, but the women under 30 chose women over men reliably more than chance. Small but significant positive correlations were found among the scores on the PCT and the belief measures; for the total sample, the greater the choice of men over women for hypothetical interactions, the greater the agreement with sex role stereotypes and with adversarial sexual beliefs. An examination of mean differences in belief scores among groups of persons whose PCT scores (choice of men over women) were low, medium, and high revealed that men who were more likely to turn away from women in hypothetical situations were also more likely to adhere to stereotyped beliefs about sex roles and to view relationships between women and men as adversarial. This same pattern of individual differences was found among women but, for women, only the relationship between PCT scores and sex role stereotyping was significant.