Show‐Jumping

This study examined the effects of the rider on the linear projectile kinematics of show‐jumping horses. SVHS video recordings (50 Hz) of eight horses jumping a vertical fence 1 m high were used for the study. Horses jumped the fence under two conditions: loose (no rider or tack) and ridden. Recordings were digitised using Peak Motus. After digitising the sequences, each rider's digitised data were removed from the ridden horse data so that three conditions were examined: loose, ridden (including the rider's data) and riderless (rider's data removed). Repeated measures ANOVA revealed significant differences between ridden and loose conditions for CG height at take‐off (p < 0.001), CG distance to the fence at take‐off (p = 0.001), maximum CG during the suspension phase (p < 0.001), CG position over the centre of the fence (p < 0.001), CG height at landing (p < 0.001), and vertical velocity at take‐off (p < 0.001). The results indicated that the rider's effect on jumping horses was primarily due to behavioural changes in the horse's motion (resulting from the rider's instruction), rather than inertial effects (due to the positioning of the rider on the horse). These findings have implications for the coaching of riders and horses.     

Skiing‐Skating

An articulated boot design is commonly used in skiing and skating sports because it allows sagittal plane ankle mobility while still providing critical frontal plane stability. Although articulated boots have been in use for several decades, current manufacturers of these boots differ in their articulation placement. In this study we determined an optimal position of the ankle articulation axis. We also calculated the amount of anterior skin movement that a boot tongue must account for during a full range of ankle motion. Three‐dimensional kinematic data were collected and analyzed from 40 participants moving their right foot through a full range of sagittal plane motion. The calculated horizontal position of the articulation axis was found to be highly predictable from foot length (r = 0.87, standard error of estimate = 3.44 mm), while its vertical component displayed less predictability (r = 0.49, standard error of estimate = 7.46 mm). The expansion required by the boot tongue had a moderate association with foot length and low variability (r = 0.58, standard error of estimate = 0.07 mm). An accurate axis placement will minimize relative motion between the boot cuff and the ankle, reducing friction and motion resistance. An expandable tongue will accommodate full plantar flexion and reduce pressure on the anterior ankle during dorsiflexion, eliminating common pressure‐related injuries.     

Cross‐Country Skiing

The purpose was to study the adaptation to speed in the temporal patterns of the movement cycle and determine any differences in velocity, cycle rate and cycle length at the maximum speed level in the different classical style and freestyle cross‐country skiing techniques. Eight skilled male cross‐country skiers were filmed with a digital video camera in the sagittal plane while skiing on a flat cross‐country ski track. The skiers performed three classical style techniques the diagonal stride, kick double poling and the double poling technique and four freestyle techniques paddle dance (gear 2), double dance (gear 3), single dance (gear 4) and combiskate (gear 5) at four different self‐selected speed levels slow, medium, fast and their maximum. Cycle duration, cycle rate, cycle length, and relative and absolute cycle phase duration of the different techniques at the different speed levels were analysed by means of a video analysis system. The cycle rate in all tested classical and freestyle techniques was found to increase significantly (p < .01) with speed from slow to maximum. Simultaneously, there was a significant decrease in the absolute phase durations of all the investigated skiing techniques. A minor, not significant, change in cycle length, and the significant increase in cycle rate with speed showed that the classical and freestyle cross‐country skiing styles are dependent, to a large extent, on an increase in cycle rate for speed adaptation. A striking finding was the constant relative phase duration with speed, which indicates a simplified neural control of the speed adaptation in both cross‐country skiing styles. For the practitioner, the knowledge about the importance of increasing cycle frequency rather than cycle length in the speed adaptation can be used to optimise a rapid increase in speed. The knowledge about the decrease in absolute phase duration, especially the thrust phase duration, points to the need for strength and technique training to enable force production at a high cycle rate and skiing speed. The knowledge that the relative phase duration stays constant with speed may be used to simplify the learning of the different cross‐country skiing techniques.     

Ritual and free‐throw shooting in basketball

The purpose of this study was to determine the nature and effect of certain highly patterned behaviours utilized prior to free‐throw shooting in basketball. Ten female basketball players comprising the varsity squad of Texas Christian University, Fort Worth, Texas, USA served as subjects for this study. Subjects were filmed with a high‐speed camera and monitored for heart rate during the performance of 10 free throws in each of two conditions: ritual and non‐ritual. For the ritual condition, subjects were given unlimited time and freedom of movement prior to each free‐throw attempt. For the non‐ritual condition, subjects were not restricted by time, but were instructed to shoot the ball without utilizing any movements other than those required to project the ball to the goal. Dependent measures were characteristics of behaviours, physiological changes measured by heart rates, mechanical data (speed, height and angle of release), and number of successful attempts. Condition x trials analyses of variance and low standard deviation concerning characteristics of behaviours indicated that the idiosyncratic behaviours prior to free‐throw shooting were rituals of the auto‐communicative type. Results indicated no significant difference between conditions for free‐throw success. However, partial correlation between dependent measures and successful free‐throw attempts indicated that duration of behaviours was most crucial to free‐throw shooting success.     

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.     

Specific muscular development in under‐18 soccer players

A comparison of the under‐18 (U‐18) and under‐16 (U‐16) squads of the Canadian national soccer team with a representative sample of Canadians (Canada Fitness Survey, 1983) showed a tendency for the development or selection of the older players in teams of stature (U‐18, 175.8 cm; U‐16, 171.1 cm; CFS, 170.9 cm) and lean body mass (U‐18, 63.4; U‐16, 57.9; CFS, 54.2 kg). The larger lean mass of the older players could not be explained simply by size. The U‐18s also showed greater isokinetic leg extension force (particularly for rapid movements) and explosive strength (vertical jump) relative to the younger players, although the knee extension force was less than in some classes of athlete. Part of the gain in mass seems due to local training of the hip and leg muscles and part to a more general muscular development. Contrary to some reports, the hip flexibility of the Canadian players (sit and reach test) was greater than for a national sample; this may be important in avoiding soft tissue injuries to the legs. However, aerobic power (58.3±5.3 ml kg^‐1 min^‐1) and body fat (8.0±l.l%) were unremarkable.     

Strength and Conditioning (Michael Stone Sub‐editor

This critical review reflects the current state of cadence research during cyclical activities at different intensities. Moreover, this review aims at making suggestions in the areas of evaluation, therapy and sporting performance in the light of all the different results reported in studies. A large number of researchers have tried to determine the ‘optimal’ cadence from imposed, preferred or spontaneously chosen cadences in order to improve efficiency and performances. Results are sometimes conflicting and difficult to explain or interpret. The authors have studied the variations in cadences using a reduced number of parameters, without links between energetic (oxygen consumption, ventilation), biomechanical (force, electromyography) and/or perceived parameters (rating of perceived exertion). Conclusions point out that the ‘optimal’ cadence cannot be unique and must be associated with the objectives and individual characteristics of the subject (skills and training level, anthropometric parameters). In the area of training and reconditioning, cadences would have to be set in relation to the nature of cyclical activities and the subjects’ condition.     

Plasma ß‐endorphin immunoreactivity: Response to resistance exercise

Previous research investigating the response of plasma ß‐endorphins (ß‐EP) to resistance exercise has resulted in equivocal findings. To further examine the effects of resistance exercise on ß‐endorphin immunoreactivity, six resistance‐trained athletes participated in a three‐set series of eight repetitions of isotonic exercise. All exercises were performed at 80% maximal effort. Blood was sampled from the group by venepuncture, both prior to and following the exercise bout, and ß‐endorphin concentration was determined by radioimmunoassay. The results indicated that mean ( ± S.E.) plasma levels of ß‐endorphins following exercise (18.04 ± 3.4 pg ß‐EP ml^‐1) were not significantly changed from pre‐exercise (control) levels (19.59 ± 2.4 pg ß‐EP ml^‐1), although there was considerable inter‐individual variability. Our results support previous research which has reported no significant changes in ß‐endorphin immunoreactivity following resistance exercise, as well as reported findings of considerable variability in the ß‐endorphin response to exercise.     

A three‐dimensional cinematographical analysis of the volleyball spike

The objectives of this study were to describe the volleyball spiking actions used by players in top‐level competition, and also to examine the interrelationships between upper limb, lower limb and whole body kinematic variables, and post‐impact ball speed in the spiking technique. Two Photosonics Biomechanics 500 cine‐cameras operating at a nominal frame rate of 100 Hz were used to film the spiking actions of 10 male senior international volleyball players at the XVI Universiade (1991 World Student Games). Three‐dimensional object space co‐ordinates of digitized image co‐ordinates were obtained using a DLT algorithm and an array of calibration points in the filmed volume. Relationships between lower limb angular kinematics at take‐off, centre of mass vertical velocity at take‐off and centre of mass vertical displacement (jump height) were examined. Relationships between angular kinematics of the hitting arm and post‐impact ball speed were also determined. The mean (± S.E.) centre of mass vertical velocity at take‐off was 3.59 ± 0.05 m s‐¹ and the mean height jumped was 0.62 ± 0.02 m. As expected, a significant correlation was found between the square of the centre of mass vertical velocity at take‐off and jump height (r = 0.78; P <0.01). No significant correlations were found between lower limb angular kinematics and centre of mass vertical velocity at take‐off or jump height. The mean post‐impact ball speed was 27.0 ± 0.9 m s‐¹, and this was significantly correlated to maximum right humerus angular velocity (r=0.75; P< 0.01). Trunk rotation angular kinematics and right elbow angular velocity did not correlate significantly with post‐impact ball speed. It was also noted that the majority of players filmed did not fit into any of the spiking categories identified in earlier studies.     

Frequency and aetiology of injury in cross‐country skiing

A comparative analysis was carried out on 1263 injured downhill skiers and 85 cross‐country skiers with regard to risk of injury, diagnosis, localization and age distribution. While 48% of the injuries to crosscountry skiers involved the upper extremities, 77% of the injuries to downhill skiers involved lesions of the leg. Contusions accounted for 31.8% in the case of cross‐country skiers, while 37.8% of downhill skiers suffered distortions, 22.8% sustained torn ligaments and 22.2% suffered fractures.

A total of 57% of downhill skiers are under the age of thirty, while 87% of cross‐country skiers are at least 30 years of age. Female cross‐country skiers tend to suffer more injuries. The chief causes are falls on downhill slopes, but also on the level usually on icy or well‐trodden courses. Another course is the ski getting caught. Good equipment, a good state of fitness and preparation, protection against hypothermia, appropriate choice of cross‐country courses and cross‐country skiing lessons are ways of preventing injuries.     

Techniques and considerations for determining isoinertial upper‐body power

Power is an integral aspect of many sports. Although power output of the lower body is often measured during jumping and cycling movements, much less is known about power as pertains to the upper body musculature. Recently, isoinertial methods ‐ with constant gravitational load ‐ of power testing have become common, but little is known of the reliability and criterion validity of these tests as they pertain to sport performance. In addition, the varied methodology makes a lucid model more evasive. The aims of this review are to examine the various methods of assessing upper body power, to establish its role in predicting athletic performance, and to assess the body of literature that has assessed power output of the upper extremities by isoinertial methods. To our knowledge, only two studies on isoinertial upper‐body power have shown a direct correlation to sporting ability (Baker, 2001; Baker et al., 2001); therefore, many unanswered questions exist as to the efficacy of these tests as predictors of athletic ability or as a method to track athletes’ training over time. From this review we hope to allow the sport coach to assess the overall utility of these tests in terms of availability, safety and external validity.     

Performance tolerance and boat set‐up in elite sprint Kayaking

The aim of this study was to examine the inter‐relationship between athlete morphology, equipment set‐up and performance in elite sprint kayaking. Correlations applied to data from the 2000 Olympics were used to select the most important links between morphology and boat set‐up — paddle grip width and foot‐bar distance. Associations between body size and the above selected equipment set‐ups were calculated using a Pearson correlation matrix, to facilitate the logical selection of independent variables as input for regression analyses. Significant (p < 0.01) regression equations were developed for the prediction of foot‐bar distance (r² = 0.589: standard error of estimate (SEE) = 4.48) and paddle grip width (r² = 0.541: SEE = 3.08). Three national‐standard sprint kayakers used their preferred set‐up together with modifications of their predicted set‐up, derived from Olympic data, to test performance tolerance in sprint kayaking. Mean coefficients of multiple determination over three trials for the three paddlers of 0.91, 0.91 and 0.92 for left paddle force, right paddle force, and paddle angle at water entry, respectively, were recorded when using their preferred set‐up. These data showed that the paddlers produce consistent patterns of motion. The intervention of altering the boat set‐up resulted in varying changes to boat speed. The mean preferred speed for the three paddlers of 4.47 m/s was reduced by 0.07 and 0.10 m/s when the above boat set‐up was modified to a predicted and ‘predicted plus one standard deviation’ respectively. These changes in boat speed were the result of alterations in the mechanics of paddling technique.     

A history of rowing in the north‐west of England

Open-boat sailing boomed in Sydney, Australia, during the 1890s, as a number of new sailing clubs emerged in the city's working waterfront suburbs. Open boats have since been remembered as ‘typically Australian’, radically opposed to the forms and ceremonies of the yachting establishment, and even as sharing the characteristics of the bushman, an archetype of Australian national identity. This article traces the rise of open-boat sailing as a working-class spectator sport and the associated image of an ‘open boat legend’. It argues that open-boat sailing remained a Sydney legend in the 1890s. However, links to working traditions and place have made it possible for popular histories of sailing and yachting to present the open boats and sailors of the period with identifiably Australian characteristics.     

Estimating propulsive forces in swimming from three‐dimensional kinematic data

Propulsive forces are important determinants of swimming performance. The aim of this study was to quantify the measurement error (uncertainty) in propulsive forces calculated from kinematic data. Ten operators digitized underwater video recordings of a breaststroke swimmer's right arm action. Four landmarks on the hand were digitized at 50 Hz and their three‐dimensional coordinates obtained using a DLT algorithm. Two angles (α and ψ) defining the orientation of the hand relative to the fluid flow were calculated following the procedures of Schleihauf et al. (1983). The hydrodynamic force acting on the hand (F _R) was calculated using the force coefficients of Schleihauf (1979). Errors in single measurements of hand speed, α and ψ were estimated for each video field analysed. Errors in α and ψ led to average errors in the lift and drag coefficients of 27 and 20% respectively, which, when combined with an average hand speed error of 6%, produced an average error in F _R of 26%. Each of these errors was reduced by a factor of √10 when the mean of 10 measurements was used to calculate F _R . Researchers should report both the estimated errors in their hydrodynamic data and the procedures used to reduce them.     

Participation Profiles and Socialisation into Dance Among Non‐Professional Dancers

Abstract

The study was designed to determine how individuals become socialised into folk, competitive ballroom, ballet and modern dance through an investigation of background variables, the influence of significant others and the participation profiles of dancers, and the identification of those socialization and involvement variables that best discriminate among different groups of dancers.

The subjects were 308 adolescent and adult dancers of at least 16 years of age who had pursued their main dance form for a minimum of three years. The data were collected by questionnaire, supplemented with some additional data gathered through personal interviews. Differences between the four dance groups were analysed using t‐test, Chi Square analyses, analyses of variance, Scheffe's multiple‐range test and discriminant analysis.

Most subjects were from the middle or upper socio‐economic classes. Most art dancers were women while social dancers displayed a more even distribution of sexes. Ballet dancers were youngest and ballroom dancers oldest when they started dancing. Mother's influence was significant among those who had started dancing at a young age while a friend of the same sex was influential among all respondents regardless of the age at which they had taken up dancing. Among men the influence of a friend of the opposite sex was also significant. The involvement of other family members in dance correlated most strongly with folk dancing, least strongly with modern dance. The dance teacher or coach was perceived as the most encouraging person in every dance form.

The most wide‐ranging past and present dance activities were found among modern dancers. The variables which best discriminated between dance forms were starting age, the variety of present dance activities and the intensity of practising one's main dance form. Such differences in socialisation into different dance forms should be taken into account when developing dance and dance teacher education curricula, teaching dance and planning recreational dance activities.

     

An examination of the cohesion‐performance relationship in university hockey teams

The objective of this study was to assess, using the Group Environment Questionnaire, whether team cohesion in university‐level field hockey was a cause for, or an effect of, successful performance. A quasi‐experimental longitudinal design with cross‐lagged correlational analysis was adopted and measures of cohesion and performance were taken midway and later in the season. The results of the synchronous correlations showed a positive relationship (with good stationarity) between team cohesion and performance outcome. Although nonsignificant cross‐lagged differentials indicated a circular relationship, the magnitudes of both the cross‐lagged correlations and the partial correlations, together with multiple‐regression analyses, revealed that the stronger flow was from cohesion to performance. The socially oriented aspects of cohesion, in particular, had significant associations with performance. The results imply that cohesion‐performance relationships should be examined within a circular model, in which cohesion and performance are interdependent.     

Effects of modelling and observer's ego involvement on warm‐up decrement

Warm‐up decrement (WUD), a phenomenon associated with motor behaviour, is the temporary decrement that occurs when performance resumes after a period of inactivity. The purpose of this study was to examine the extent to which observing a model while concerned about one's own subsequent performance (e.g. a substitute about to enter the sport contest) influences WUD. The subjects were randomly assigned to one of four conditions: (1) observing an ego‐involved model demonstrate the criterion skill, (2) observing a model while not ego‐involved, (3) ego involvement without modelling and (4) resting (control). Performance outcome (accuracy) and arousal (cognitive and somatic) were assessed. The results of the study indicated that only the combined ego involvement plus modelling condition eliminated WUD. Positive rather than negative emotions and heart rate increased significantly for these subjects after rest. In contrast, the other conditions each exhibited WUD. Heart rate was significantly higher in the ‘model and ego’ and ‘ego only’ groups as opposed to ‘modelling only’ and rest. Implications for using cognitive strategies while observing competitors just prior to entering the contest on reducing WUD are discussed.     

Optimized and corrected peak power output during friction‐braked cycle ergometry

Assessments of maximal intensity exercise which determine peak power output on friction‐baked cycle ergometers have fallen into two categories: correction procedures which account for changes in momentum of the ergometer's flywheel and optimization procedures which attempt to satisfy muscle force‐velocity relationships. The aim of this study was to compare performance in each procedure and so investigate assumptions which underpin the tests. Nineteen males aged 20.9 ± 0.4 years and 18 females aged 22.2 ± 0.7 years (mean ± S.E.M.), who were fully accustomed to the procedures, participated in a single experimental protocol. After a 5 min warm‐up, the subjects performed four bouts of all‐out exercise on a Monark 814E cycle ergometer against randomly assigned loads. The loads were selected to produce peak pedalling rates in the range 100–200 rev min^?1 and each bout lasted 10 s. From the inverse linear relationship between applied load and peak pedalling rate, optimized peak power output (PP _opt) and the accompanying pedalling rate (RPM _opt) were calculated. One of the bouts used a loading equivalent to 7.5% of body weight and for this bout corrected peak power output (PP _corr) and its corresponding pedalling rate (RPM _corr) were calculated. The PP _opt was less than PP _corr in the males (915 ± 35 vs 1005 ± 32 W) and females (673 ± 33 vs 777 ± 39 W) (both P < 0.001). Similarly, RPM _opt was less than RPM _corr (111 ± 1 vs 128 ± 2 rev min^?1 and 101 ± 1 vs 111 ± 2 rev min^?1 in the males and females, respectively; P < 0.001). The results demonstrate that optimization and correction procedures produce different values of performance. These differences are probably attributable to the mechanical principles which underpin the tests.