Relationship of Individual Differences and Subsequent Changes in Static Strength with Speed of Forearm Flexion Movement

Abstract

This study investigated the relationship between strength and speed of forearm flexion and compared the effect of three methods of training on speed of forearm flexion movement. Ninety-one university freshmen were tested for maximum static strength, forearm mass, and speed of forearm flexion. They were assigned to four groups: control, speed of movement, isometric, and isotonic. After an 8-week experimental program, subjects were tested again for strength, mass, and speed of forearm flexion movement. Low positive relationships, significant at the .05 level, between static strength and speed of forearm flexion were found in this study. When static strength was related to the mass which was moved during movement, correlations between strength/mass and speed were not significant. The results of both correlational computations and covariance analysis indicated that increasing the strength of the muscles which move a limb does not result in a corresponding increase in the speed with which the limb can be moved.     

Maximal Work Capacity of Human Intact Muscle under Hyperaemic Conditions

Abstract

Fatigue curves for the forearm muscles, doing maximal static and dynamic work, were obtained under control conditions and under conditions of hyperaemia. The hyperaemia was evoked by subjecting the muscles of the forearm for a specific length of time to circulatory occlusion with a blood pressure cuff and then suddenly releasing the cuff pressure. The maximal increase in forearm volume, resulting from the postocclusion hyperaemia, followed a mathematical curve when it was expressed as a function of the occlusion time. A significant decrement in work capacity was found immediately after ten minutes of occlusion. This short-time negative influence did not affect the total output.     

Stress and performance: An application of Gray's three‐factor arousal theory to basketball free‐throw shooting

The suitability of Gray's (1975) three‐factor arousal theory as a model of human performance under stress was investigated in a study of basketball free‐throw shooting. Free‐throw attempts, made by members of an NCAA Division I men's varsity team, were videotaped during one full season. On the basis of Gray's theory, we predicted that increased stress (assumed to be present in games as opposed to practices) would be associated with longer pre‐shot preparations and a greater incidence of overthrow shots. The prediction was confirmed by the results. Moreover, we found that free‐throws were more frequently overthrown when attempted during crucial rather than non‐crucial game situations. Further tests of the utility of Gray's theory are suggested.     

Anthropological status of international calibre speed skaters

The purpose of the study was to determine the anthropological status of elite male and female speed skaters, who were members of the 1985–7 Canadian national teams. The data were compared to those for a control group of University students. The subjects were 8 males and 6 females between 19 and 27 years of age. Nine breadth, 14 girth, 16 length and 15 skinfold measurements were used to compute parameters of body build and the composition; corrected diameters, masses, volumes and fat‐free volumes of the upper arm, forearm, thigh and calf. The speed skaters were found to be similar in body height and mass (males: 178 ± 7.6 cm and 75.5 ± 5.5 kg, females: 165.8 ± 3.8 cm and 62.3 ± 5.8 kg) to the student controls, but they had relatively and absolutely shorter legs and longer trunks. The speed skaters had a lower amount of body fat and higher FFM than their respective student controls and significantly greater relative (P ≤ 0.01) and absolute (P ≤ 0.05) total muscle mass. Analysis of composition within segments indicated that the additional muscle mass is located entirely in the lower extremity. The volume and mass of the thigh was greater (P ≤ 0.01 for the males) than that of the respective controls while the estimated volume of fat was lower. The female speed skaters were found to have more fat on their thigh than either the male speed skaters or male controls. The corrected diameter and mass of the thigh were greater (with respect to the sex) than those reported for 400 m sprinters, marathon runners, cross‐country skiers and figure skaters. The results of the initial assessment were compared to the two consecutive tests of the men's team (conducted 8 and 12 months later) and to one repeated test of the women's team (3 months later). Changes were recorded in skinfold measurements and the muscle component of the thigh.     

Relationship of Heath and Carter's Second Component to Lean Body Mass and Height in College Women

Abstract

The purpose of this study was to compare Heath and Carter's anthropometric approach with the multiple regression technique for the prediction of lean body mass (LBM). Lean body mass was estimated from whole-body ⁴⁰K spectrometry and body density in college-age women. Heath and Carter's second component correlates .40 with LBM (density)/height and .24 with LBM (⁴⁰K)/height. The correlations are quite low and indicate that LBM per unit of height is not closely related to the second component. When lean body mass and height were used together in multiple regression analysis as separate predictors instead of a ratio, 48% of the variation was accounted for in the second component. A test of validity of the measures used to calculate Heath and Carter's second component was evaluated through the use of multiple regression analysis, incorporating height and anthropometric measures as independent variables and LBM from density and ⁴⁰K as dependent variables. The muscle circumferences but not skeletal widths in the Heath and Carter method were found to be valid predictors of LBM through regression analysis. LBM is predicted with a standard error of estimate of 2.2 kg using the anthropometric variables of Heath and Carter's second component. This error is comparable to the results of other anthropometric predictions of LBM in college-age women.     

Study of Endurance of Various Muscle Groups

Abstract

Endurance of three muscle groups was studied ergometrically: flexors of the forearm in 30 subjects, flexors of the hand, and extensors of the lower leg in 20 subjects. The flexors of the forearm were tested with two ergometers: the lever and the pulley type. The load used was equal to one-third of the maximum strength of the respective muscle group. Tests-retests gave the following coefficients of reliability: arm pulley ergometer, .91; arm lever ergometer, .89; grip ergometer, .88; and leg ergometer, .75. The coefficients of correlation between performance times were: arm pulley and arm lever ergometers, .91; arm pulley and leg ergometers, .53; arm pulley and grip ergometers, .68; grip and leg ergometers, .58; arm lever and grip ergometers, .30. All r's except the last one were statistically significant.     

Anticipation by basketball defenders: An explanation based on the three-dimensional inverted pendulum model

Abstract

We previously estimated the timing when ball game defenders detect relevant information through visual input for reacting to an attacker's running direction after a cutting manoeuvre, called cue timing. The purpose of this study was to investigate what specific information is relevant for defenders, and how defenders process this information to decide on their opponents' running direction. In this study, we hypothesised that defenders extract information regarding the position and velocity of the attackers' centre of mass (CoM) and the contact foot. We used a model which simulates the future trajectory of the opponent's CoM based upon an inverted pendulum movement. The hypothesis was tested by comparing observed defender's cue timing, model-estimated cue timing using the inverted pendulum model (IPM cue timing) and cue timing using only the current CoM position (CoM cue timing). The IPM cue timing was defined as the time when the simulated pendulum falls leftward or rightward given the initial values for position and velocity of the CoM and the contact foot at the time. The model-estimated IPM cue timing and the empirically observed defender's cue timing were comparable in median value and were significantly correlated, whereas the CoM cue timing was significantly more delayed than the IPM and the defender's cue timings. Based on these results, we discuss the possibility that defenders may be able to anticipate the future direction of an attacker by forwardly simulating inverted pendulum movement.     

Relative Endurance of High- and Low-Strength Women

Abstract

The purpose of this study was to analyze the relative endurance ability of women in terms of muscle mass, static muscle strength, and critical occluding tension levels (COTL). Women physical education majors volunteered as subjects for this study (N = 56). The percentages of grip strength used for the relative endurance tests were 30%, 45%, 60%, and 75% with local circulation to the forearm muscles intact and artificially occluded by a pressure cuff. Analysis of the data revealed that there was no significant difference in the endurance times of high- and low-strength women. The relationship between grip strength and relative endurance time for each tension level was insignificant (r = ?.23 to ?.34). These findings were discussed in light of the relatively small differences in muscle mass and similarity in COTL of high- and low-strength women.     

Kinematic differences in upper limb joints between flat and topspin forehand drives in competitive male tennis players

Abstract

The topspin tennis forehand drive has become a feature of modern game; yet, as compared to the serve, there has been little research analysing its kinematics. This is surprising given that there is considerably more variation in the execution of the topspin forehand. Our study is the first to examine the amplitude of upper limb joint rotations that produce topspin in the forehand drives of 14 male competitive tennis players using video-based motion analysis. Humerothoracic abduction (-)/adduction (+), extension (-) /flexion (+), and external (-)/internal (+) rotation, elbow extension (-) /flexion (+) and forearm supination (-)/pronation (+), wrist extension (-)/flexion (+) and ulnar (-)/radial (-) deviation were computed. Our findings revealed that the generation of topspin demanded more humeral extension and forearm pronation but less humeral internal rotation angular displacement during the forwardswing. The follow-through phase of the topspin shot was characterised by greater humeral internal rotation and forearm pronation, and reduced humeral horizontal adduction when compared to the flat shot. This study provides practitioners with a better understanding of the upper limb kinematics associated with the topspin tennis forehand drive production to help guide skill acquisition interventions and physical training.     

Treatment Discrimination among Assistant Coaches of Women's Teams

Abstract

The purpose of this study was to examine organizational treatment discrimination (i.e., when members of a group receive fewer rewards, opportunities, or resources than they legitimately deserve based on job-related criteria) in the context of women's athletics. Data were collected from 170 assistant coaches of women's teams (i.e., women's basketball, softball, track, volleyball, soccer, and tennis). Results indicate that women's perceived work experiences and outcomes were comparable, and sometimes better, than those of men. We present competing explanations for this finding. First, it is possible that these women were not subjected to treatment discrimination. Alternatively, it is possible that this demonstrates the existence of the “paradox of the contented working woman.” Additional analyses indicate that work experiences explained a large portion of the variance in organizational commitment and turnover intentions, thereby demonstrating their importance in the workplace.     

Selected Physiological Responses of Normal Young Men following Dehydration and Rehydration

Abstract

This study was designed to compare man's normal working physiological performance to that during rapid dehydration and rehydration. Seven trained men participated in submaximal exercise trials at three conditions (normal, dehydrated, and rehydrated). During each test measurements were recorded on the subject's rectal temperature change during exercise and recovery, exercise and recovery minute heart rates, minute volume, oxygen consumption, respiratory quotient, ventilatory efficiency, and oxygen pulse. Analysis of the data, employing analysis of variance and Duncan's Multiple Range Test, indicated significant differences in mean exercise and second minute recovery heart rates, with an elevation during the dehydration test, and a return to normalcy for the rehydration test. Oxygen pulse decreased notably with dehydration, returning to normal with rehydration. Mean rectal temperature change, first minute recovery heart rate, oxygen consumption, ventilatory efficiency, minute volume, and respiratory quotient did not exhibit significant change.     

Anticipatory strategies of team-handball goalkeepers

Abstract

This study seeks to discover whether handball goalkeepers employ a general anticipatory strategy when facing long distance throws and the effect of uncertainty on these strategies. Seven goalkeepers and four throwers took part. We used a force platform to analyse the goalkeeper's movements on the basis of reaction forces and two video cameras synchronised at 500 Hz to film the throw using 3D video techniques. The goalkeepers initiated their movement towards the side of the throw 193 ± 67 ms before the release of the ball and when the uncertainty was reduced the time increased to 349 ± 71 ms. The kinematics analysis of their centre of mass indicated that there was an anticipatory strategy of movement with certain modifications when there was greater uncertainty. All the average scores referring to velocity and lateral movement of the goalkeeper's centre of mass are significantly greater than those recorded for the experimental situation with bigger uncertainty. The methodology used has enabled us to tackle the study of anticipation from an analysis of the movement used by goalkeepers to save the ball.     

Effect of Hand Spacing and Rear Knee Angle on the Sprinter's Start

Abstract

Twelve male subjects with no specialized training in sprint running were used to study effects upon the sprinter's start when hand spacing and rear knee angle were systematically altered. Results indicated that hand spacing had an effect on the start during the first 10 yd. of the sprint. The effect of rear knee angle was present at 10 yd. and the advantage gained at 10 yd. was still present at 30 yd.     

A Latent Growth Curve Approach to Investigating Developmental Dynamics and Correlates of Change in Children's Perceptions of Physical Competence

Abstract

In both the physical and academic domains interest has recently grown regarding developmental change in children's perceptions of competence. Recent advances in statistical methodology, such as latent growth modeling, enable the researcher to analyze developmental trends from both an inter- and intraindividual perspective, thus serving to increase our understanding of correlates of change in perceived competence. Using latent growth modeling, the purpose of the present study was to investigate developmental change in children's perceived competence at physical skills, examining maturational factors and chronological age as possible correlates of change. Subjects were male adolescents (N = 94). Data were collected during the child's sixth, eighth, and ninth grade school years. Results revealed a good fit for the hypothesized model, which specified mean level changes in the variables over time and an interrelationship among the latent chronometric common factors. Although a significant relationship existed between maturation and perceived competence, no significant relationship was evident between chronological age and perceived competence. Findings are discussed with particular reference to the utility of latent growth curve models for assessing developmental processes at both the inter- and intraindividual level.     

Is bioelectrical impedance spectroscopy accurate in estimating changes in fat-free mass in judo athletes?

Abstract

Bioelectrical impedance spectroscopy (BIS) provides an affordable and practical assessment of fat-free mass (FFM). However, little information is available on the assessment of changes in fat-free mass in top-level athletes using BIS. The aim of this study was to examine the accuracy of BIS in tracking changes in fat-free mass of elite male judo athletes from a period of weight stability to just before competition, using the four-compartment model (4C model) as reference method. In total, 27 elite male judo athletes (age 22.2 ± 2.8 years) were evaluated. Measures of body volume assessed by air displacement plethysmography, bone mineral content by dual-energy X-ray absorptiometry, and total-body water assessed with deuterium dilution were used in a 4C model. Fat-free mass was also assessed by BIS (FFM_BIS). Changes in FFM_BIS were not significantly different from measured by the reference method (P = 0.000). Furthermore, the r ² was 0.62 and the standard error of the estimate was 1.03 kg. The limits of agreement ranged from ?3.36 to 2.59 kg with no bias observed. These findings demonstrate the viability of BIS as a valid tool for tracking fat-free mass in elite male judo athletes. However, based on the wide limits of agreement observed, BIS is less valid at an individual level for tracking fat-free mass in these athletes.     

Sport specificity background affects the principal component structure of vertical squat jump performance of young adult female athletes

PurposeLong-term training specificity is thought to alter performance in tests evaluating strength and power production capability. The aim of the present study was to provide additional information to the limited existing knowledge concerning the possible differences of the force/time profile of squat jumping among different groups of young female athletes.MethodsOne hundred and seventy-three adult women (20.1 ± 2.8 years, 1.71 ± 0.09 m, 65.6 ± 10.3 kg, mean ± SD for age, height, and mass, respectively) engaged in track and field (TF), volleyball (VO), handball (HA), basketball (BA), and physical education students (PE) executed maximal squat jumps (SQJ) on a force plate. Pearson's correlation was used to identify the relationship between SQJ performance, the anthropometric characteristics and the biomechanical parameters. Differences concerning the biomechanical parameters among groups were investigated with analysis of variance, while the force- (FPD) or time- (TPD) dependency of SQJ execution was examined using principal components analysis (PCA).ResultsSQJ was unrelated to body height but significantly correlated with body mass (r = −0.26, p = 0.001). TF jumped higher and produced larger peak body power output compared to all the other groups (p < 0.05). All athletes were superior to PE since they performed the SQJ with a longer (p < 0.05) vertical body center of mass trajectory during the propulsion phase. PCA results revealed that TF significantly differentiated than the other groups by relying on FPD.ConclusionVarious different profiles of FPD and TPD were detected due to different sporting background in young female athletes. Since TF superiority in SQJ was relied on the larger power production and a greater FPD, female indoor team sport athletes are suggested to execute jumping exercises adopting the jumping strategies utilized by TF.     

Effect of Selected Doses of Alcohol on Fatigue Parameters of the Forearm Flexor Muscles

Abstract

The purpose of the present study was to enhance knowledge of the effect of alcohol on physical performance by analyzing the effect of a small and moderate dose of alcohol on several aspects of muscular strength and endurance; in addition to the standard dosages, a large dose was given to an experimental subgroup. The parameters studied included initial strength, maximal strength, steady state or final strength, total work, fatigable work and the rate of fatigue of the forearm flexors. Male university students (N = 35) served as subjects and underwent three trials of a standardized work task consisting of intermittent maximum contractions of the forearm flexors performed at the rate of 30/min. for 6 min. Prior to each trial, each subject consumed either a control, small, or moderate dose of alcohol. The statistical analysis indicated that a small or moderate dose of alcohol had no effect on five of the parameters under investigation. The mathematical analysis of the rate of fatigue indicated rather large differences between the main rate constants, but the findings must be interpreted cautiously due to the insignificant nature of the statistical analysis. It was concluded that a small or moderate amount of alcohol had no effect on the strength and endurance variables under investigation.     

Attitudes,Beliefs, Behavioral Intentions,and Behaviors of Women and Men toward Regular Jogging

Abstract

Fishbein's Behavioral Intention Model was examined in a study of the beliefs, attitudes, and behavioral intentions of women and men toward regular jogging. Data were collected from 296 female and male joggers and nonexercisers who were 30 years of age and older using a mail questionnaire which was constructed according to Fishbein's specifications. Significant and meaningful differences were found between joggers' and nonexercisers' beliefs. Nonexercisers thought jogging would require too much discipline, take too much time, and make them too tired. Joggers were more likely than nonexercisers to believe that regular jogging would have positive effects, and joggers evaluated being in good physical and mental condition more positively than nonexercisers. Nonexercisers indicated it was unlikely their referents (particularly physicians) thought they should jog regularly. The results supported the theory upon which the model was based: the relationship between the intention to jog and jogging behavior was high (r = .82) and behavioral intention was predicted from an attitudinal and a normative component alone (R = .742). The results of the study suggest that educators can develop behavior change strategies by focusing on change of beliefs and attitudes identifiable through the model.     

The effect of active sitting on trunk motion

BackgroundProlonged sitting is a risk factor for low-back pain. The primary purpose of this study is to determine if prolonged active sitting will result in increased trunk motion.MethodsFifteen healthy female participants volunteered to sit for 30 min on each of three surfaces including an air-cushion, a stability ball, and a hard surface. Trunk motion was monitored using a Vicon motion capture system, and foot center of pressure was collected with two AMTI force plates.ResultsOur findings indicated that the average speed of the trunk center of mass significantly increased with seating surface compliance. There were significant differences in right and left foot centers of pressure in the antero-posterior direction between the ball and air-cushion conditions and the ball and chair conditions.ConclusionActive sitting results in increased trunk motion and could have a positive effect on low-back health.     

Anthropometric assessment of Premiership soccer players in relation to playing position

Abstract

A squad of Premiership soccer players (n=24) provided informed consent to participate in this study. Using ISAK (International Society of Advancement of Kinanthropometry) accredited methods, a total of 39 measurements (sectioned as: skinfolds, girths, lengths, and breadths) were made for each player. The procedure involved three measures at each site to calculate a mean value and an acceptable technical error margin. All data collection was performed by an ISAK level 3 accredited anthropometrist. The data analysis consisted of demographic and anthropometric data, including fractionation of body mass and estimated body fat from sum of skinfolds. Scaling of the raw data was done by using the phantom strategem to obtain calculated data for inter-player comparison. Mean calculated scores for playing position were obtained. A multivariate analysis of variance revealed no differences between positions (F _15,41.810=0.783, P=0.688). Previous studies have reported heterogeneity between playing positions. However, in this study, stature and body mass were not different between strikers, midfielders, defenders, and goalkeepers. Research has suggested that a soccer player's anthropometric dimensions can be a major determinant for success within a playing position. In this study, within-position variation was quite large in some cases, which could indicate that a team that does not have the opportunity to hand-pick players, based on anthropometric characteristics, may be at a disadvantage.