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1.
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.  相似文献   

2.
ABSTRACT

Background: Over the past 10 years, research has started to investigate the pedagogic practices of instructors and coaches working in adventure sports settings. Outdoor instructors face particular challenges regarding the impact the dynamic environment has on the coaching process and their students. This challenging combination of factors obliges the instructor to be agile in response. We propose that this adaptive expertise is characteristic of these factors and that adaptability may be a beneficial focus of outdoor instructor training and education.

Purpose: The major aim was to identify if adaptive expertise is an attribute of outdoor instructors? And if so, what are its characteristics in this context?

Research design and data collection: We applied a mixed methodology to a sample of outdoor instructors (n?=?64). The instructors were asked to complete a quantitative adaptive expertise inventory. We then interviewed a selected sub-sample (n?=?12).

Participants and setting: Quantitative data was collected from outdoor instructors working in the UK (n?=?64). The sample consisted of instructors qualified to work independently with groups in adventurous settings in a range of activities. Qualitative data was collected from a smaller sample (n?=?12) via a series of thematically analysed semi-structured interviews.

Findings: Results suggest that the participating outdoor instructors have high levels of adaptive expertise. A characteristic of that adaptive capacity is a combination of skills revolving around reflection, metacognition, and situational awareness. There were differences, however, between less and more experienced outdoor instructors in their adaptive capacity, with less experienced instructors being adaptive to a lesser extent.

Conclusions: The implication is that further research is worthwhile to examine the development of instructors’ adaptive capacity. The training and education of outdoor instructors requires pedagogic approaches that facilitate and engender adaptability, flexibility and agility in neophyte instructors.  相似文献   

3.
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4.
Purpose: The purpose of the present study was to investigate the effects of self-controlled feedback on the learning of a sequential-timing motor task in introverts and extroverts. Method: Fifty-six university students were selected by the Eysenck Personality Questionnaire. They practiced a motor task consisting of pressing computer keyboard keys in a specific spatial and temporal pattern. The experiment consisted of practice, retention, and transfer phases. The participants were distributed into 4 groups, formed by the combination of personality trait (extraversion/introversion) and type of feedback frequency (self-controlled/yoked). Results: The results showed superior learning for the groups that practiced in a self-controlled schedule, in relation to groups who practiced in an externally controlled schedule, F(1, 52) = 4.13, p < .05, η2 = .07, regardless of personality trait. Conclusion: We conclude that self-controlled practice enhances motor learning in introverts and extroverts.  相似文献   

5.

Purpose: The aim of this study was to ascertain the biomechanical differences between better and poorer performers of the vertical jump in a homogeneous group of children. Method: Twenty-four girls were divided into low-scoring (LOW; M age = 6.3 ± 0.8 years) and high-scoring (HIGH; M age = 6.6 ± 0.8 years) groups based on their performance on the vertical jump. The force-, velocity-, displacement-, and rate of force development (RFD)-time curves of vertical jumps were analyzed to determine the differences between groups. Results: The analysis of the data showed differences in the pattern of the ensemble mean curves of the HIGH and LOW groups, although the majority of the differences occurred during the eccentric contraction phase of the jump. The differences in the HIGH group with respect to the LOW group were: lower force at the beginning of the movement, higher speed and RFD during the eccentric phase, high force at the beginning of the concentric phase, higher velocity during the concentric phase, and a higher position at takeoff. Conclusion: The results showed that the HIGH group achieved a higher jump height than did the LOW group by increasing the effectiveness of the countermovement and achieving a more advantageous position at takeoff.  相似文献   

6.

Purpose: To describe the development and preliminary evaluation of the Multicontext Sitting Time Questionnaire (MSTQ). Method: During development of the MSTQ, contexts and domains of sitting behavior were utilized as recall cues to improve the accuracy of sitting assessment. The terms “workday” and “nonworkday” were used to disambiguate occupational and discretionary sitting. An expert panel evaluated content validity. Among 25 participants, test–retest reliability of the MSTQ items was assessed with intraclass correlation coefficients (ICCs). Convergent validity was assessed versus relative and absolute accelerometer-estimated sedentary time and activity log using Pearson (r) or Spearman (ρ) correlation coefficients where appropriate. Results: Pilot testing revealed Web-based MSTQ administration was rapid, scalable, and inexpensive. Most items in the MSTQ demonstrated acceptable reliability (ICCs>.70). Compared with accelerometer-estimated sedentary time relative to total wear time, the MSTQ exhibited a low correlation on workdays (r = .34) and a moderately high correlation on nonworkdays (r = .61). Conclusions: The systematic development of the MSTQ resulted in several improvements over previous tools and may serve as a model for purpose-driven questionnaire design. Additional validation is needed to conclusively determine the utility of the MSTQ.  相似文献   

7.
Abstract

Introduction: In response to fatigue during an exhaustive treadmill run, forefoot runner’s muscles must adapt to maintain their pace. From a neuromuscular control perspective, certain muscles may not be able to sustain the force to meet the run’s demands; thus, there may be alternative muscle coordination in the lower extremity that allows for continued running for an extended period of time. The aim of this study was to quantify the change in muscle coordination during a prolonged run in forefoot runners.

Methods: Thirteen forefoot runners performed exhaustive treadmill runs (mean duration: 15.4?±?2.2?min). The muscle coordination of seven lower extremity muscles was quantified using a high-resolution time–frequency analysis together with a pattern recognition algorithm.

Results: The mean EMG intensity for the lateral and medial gastrocnemius muscles decreased with the run (p?=?0.02; 0.06). The weight factors of the second principal pattern decrease by 128.01% by the end of run (p?=?0.05, Cohen’s d?=?0.42) representing a relatively greater biceps femoris activation in midstance but smaller midstance rectus femoris, vastus medialis, triceps surae, and tibialis anterior activation.

Discussion: These results suggest that forefoot runners cannot sustain plantar flexor activation throughout an exhaustive run and change their muscle coordination strategy as a compensation. Understanding the underlying compensation mechanisms humans use to cope with fatigue will help to inform training modalities to enhance these late stage muscle activation strategies for athletes with the goal of improving performance and reducing injury.  相似文献   

8.
Purpose

This study investigated whether within-task expertise affects the reported asymmetry in execution time exhibited in reactive and self-initiated movements.

Method

Karate practitioners and no-karate practitioners were compared performing a reverse punch in reaction to an external stimulus or following the intention to produce a response (self-initiated). The task was completed following the presentation of a specific (i.e., life-size image of opponent) or general stimulus and in the presence of click trains or white noise.

Results

Kinematic analyses indicated reactive movement had shorter time to peak velocity and movement time, as well as greater accuracy than self-initiated movement. These differences were independent of participant skill level although peak velocity was higher in the karate practice group than in the no-karate practice group. Reaction time (RT) of skilled participants was facilitated by a specific stimulus. There was no effect on RT or kinematic variables of the different type of auditory cues.

Conclusions

The results of this study indicate that asymmetry in execution time of reactive and self-initiated movement holds irrespective of within-task expertise and stimulus specificity. This could have implications for training of sports and/or relearning of tasks that require rapid and accurate movements to intercept/contact a target.  相似文献   

9.
ABSTRACT

Background: School-based physical education has been associated with a multitude of potential learning outcomes. Representatives of a public health perspective suggest that promoting physical activity in and outside the context of school is an important endeavour. While the importance of behavioural skill training to improve (motor) learning is well documented in both general and physical education, the promotion of behavioural skills to foster physically active lifestyles constitutes a rather neglected area in physical education research.

Purpose: To examine whether a standardized physical education-based behavioural skill training program has the potential to positively impact on adolescents’ self-reported exercise and sport participation, as well as cognitive antecedents involved in the regulation of exercise and sport behaviour.

Research design: Cluster-randomized controlled trial.

Methods: A sample of 143 secondary school students (50% girls, aged 14–18 years) attending academic high schools in German-speaking Switzerland were assigned class-wise to the intervention (behavioural skill training) and control condition (conventional physical education lessons). Data were assessed prior and after completion of the 7-week intervention program, which was composed of four 20-min lessons and two reflection phases. Exercise and sport behaviour and cognitive antecedents (exercise/sport intention, motivation, implementation intentions, coping planning, self-efficacy) were assessed via self-reports. A multilevel mixed effects linear regression procedure was used to test the main hypotheses. The regression analyses were adjusted for clustering of school classes, and controlled for baseline levels of the outcome measure and potential confounders.

Results: Compared to a control condition, the intervention program resulted in significant improvements with regard to introjected motivation (p?<?.05), coping planning (p?<?.001) and self-efficacy (p?<?.01). The intervention also had a positive impact on adolescents’ self-reported sport/exercise behaviour (p?<?.001). Improvements in exercise/sport intention (p?<?.05), coping planning (p?<?.01), and self-efficacy (p?<?.01) were associated with increased levels of self-reported exercise/sport participation.

Conclusion: Behavioural skill training as part of compulsory physical education has the potential to improve cognitive antecedents of exercise and sport behaviour and to foster adolescents’ exercise and sport participation. Enhancing behavioural skills might be one way in which school physical education can contribute to the creation of more physically active lifestyles among adolescents.  相似文献   

10.

Purpose: The purpose of the meta-analysis was to examine the effectiveness of physical activity interventions on physical activity participation among preschoolers. A secondary purpose was to investigate the influence of several possible moderator variables (e.g., intervention length, location, leadership, type) on moderate-to-vigorous physical activity (MVPA). Method: Nine databases were systematically searched for physical activity interventions. Studies were included if they contained statistics necessary to compute an effect size (ES), were written in or translated into English, examined physical activity in preschoolers, incorporated a physical activity intervention, and targeted preschool-aged children. Fifteen studies satisfied these criteria. ESs were calculated using a random-effects model. Results: Results indicated that overall, interventions had a small-to-moderate effect on general physical activity (Hedges g = 0.44, p < .05, n = 73 ESs) and a moderate effect on MVPA (Hedges g = 0.51, p < .05, n = 39 ESs). The greatest effects for MVPA were identified for interventions that were less than 4 weeks in duration, were offered in an early-learning environment, were led by teachers, involved outdoor activity, and incorporated unstructured activity. Conclusions: This meta-analysis provides an overview and synthesis of physical activity interventions and highlights effective strategies for future interventions aimed at increasing physical activity levels among preschoolers.  相似文献   

11.
Background: A distinction is made in Achievement Goal Theory (AGT) between task-oriented (i.e. effort, intra-individual progress, and self-comparison) and ego-oriented (i.e. inter-individual progress and normative comparison) climates. Combining insights from AGT and Self-Determination Theory (SDT), studies in the PE context have shown that a task-oriented climate positively relates to need satisfaction, although the findings regarding the motivating role of an ego-oriented climate are inconsistent. Moreover, little is known about the role of task- or ego-oriented climates in explaining experiences of basic psychological need frustration.

Purpose: Grounded in AGT and SDT, the aim of the present study was to examine if experiences of basic psychological need satisfaction and need frustration can explain why task- and ego-oriented climates elicit positive and negative motivational outcomes in PE, respectively.

Research design: Cross-sectional study.

Method: A sample of 524 secondary school students (51.1% boys, Mage?=?14.51; SD?=?1.81) from five different secondary schools participated in this study. Students reported on their perceptions of task- and ego-oriented climates, motivational regulations, basic psychological need satisfaction, and need frustration, as well as positive and negative outcomes in PE. Structural equation modeling was used to investigate our objective.

Results: We found that a task-oriented climate had a strong and positive relationship with basic psychological need satisfaction, eliciting a bright pathway to autonomous motivation and affective attitude. An ego-oriented climate was positively related to basic psychological need frustration, eliciting a dark pathway to amotivation and boredom. A negative cross-path from task-oriented climate to basic psychological need frustration was also found, while no significant cross-paths were found from ego-oriented climate to basic psychological need satisfaction.

Conclusions: This study provides a better understanding of the mechanisms that explain why task- and ego-oriented climates shape students’ motivational experiences in PE lessons. It is suggested that a task-oriented climate elicits a bright pathway towards more optimal functioning, because it fosters experiences of need satisfaction and buffers against experiences of need frustration. In contrast, an ego-oriented climate is primarily positively related to feelings of need frustration and negative motivational outcomes. Practical implications for PE teacher training are discussed.  相似文献   

12.
Purpose: Acute benefits of aerobic exercise on executive functioning have been reported frequently under laboratory conditions. However, to date, a beneficial effect on long-term memory has been less well supported and no data are available regarding nonlaboratory conditions in young adults. The aim of the current study was to investigate acute effects of aerobic exercise on cognitive functioning in a university classroom setting. Method: Using a cross-over design, 51 participants performed a bout of moderately intense running (RUN) and read an article while seated (CON). Afterwards, they completed free-recall tests, followed by a Flanker task and an n-back task. Results: Participants in the RUN condition compared with those in the CON condition showed shorter reaction time on the inhibition task, F(1, 50) = 5.59, p = .022, η2 = .101, and recalled more words in the immediate- and delayed-recall tests, F(1, 50) = 8.40, p = .006, η2 = .144. Conclusion: The present findings suggest that a moderately intense bout of aerobic exercise benefits verbal short-term and long-term memory as well as inhibitory control among students in a classroom setting.  相似文献   

13.
ABSTRACT

Background: Bullying is a social problem where there is a phenomenon of intentional aggression that occurs in all schools. It has multiple negative consequences for the victim’s psychological health. As school is a context for learning about life in society, strategies to prevent such attitudes and behaviours should be encouraged. Although some studies seem to indicate the potential of the subject of physical education to promote attitudes and behaviours against bullying, there is still insufficient scientific evidence to deduce a positive impact on the reduction or prevention of this phenomenon.

Purpose: This study aimed to analyse the effectiveness of a specific intervention to prevent bullying in Physical Education classes in Secondary Education. 6 specific sessions inserted into the physical education curriculum to find out what bullying is, who its protagonists are and how to prevent it.

Participants and setting: In the study, 764 students with an age range of 12–19 years (49.3% girls; age mean [M]?=?14.80, standard deviation [SD]?=?1.69) from two public educational centres participated. Among them, 439 were randomly assigned to the quasi-experimental group (48.1% girls; age M?=?14.70, SD?=?1.59) and 325 to the control group (51.1% girls; age M?=?14.94, SD?=?1.83). Data were collected at two timepoints, pre- and the post-intervention data.

Data collection: The Spanish version of the European Bullying Intervention Project Questionnaire (EBIPQ) was used to measure the incidence of bullying. To measure cyberbullying, the Spanish version of the European Cyberbullying Intervention Project Questionnaire (ECIPQ) scale was used.

Data analysis: The Student t-test was performed to compare possible differences between the experimental and control groups in the pre-test. To compare the means of the factors obtained based on the variables and the instruments used, as well as the scores obtained from the subjects of the experimental and control groups at the two timepoints, linear models of repeated measurements have been established comparing the pre- and post-intervention moments and the experimental and control groups, introducing sex and grade variables to compare the effectiveness of the programme based on them.

Results: There were no differences in the pre-test measurements in any of the variables. After the intervention programme in the quasi-experimental group, the bullying victimisation (F?=?16,951; p?=?.000) and bullying aggression (F?=?5,215; p?=?.023) rates decreased significantly more than they did the control group. Likewise, victimisation in cyberbullying (F?=?6,234; p?=?.013) decreased significantly differently, but aggression in cyberbullying did not (F?=?0,099; p?=?.753).

Conclusion: The implementation of a specific intervention to prevent bullying inserted into the physical education curriculum seems to have decreased bullying and cyberbullying victimisation.  相似文献   

14.
Objectives: This study aimed to evaluate the levels of 8-isoprostane (8-IsoP) in the airways of competitive swimmers at baseline and after a swimming session according to their airway responsiveness. Methods: Twenty-three swimmers and six lifeguards had a baseline spirometry and bronchoprovocative challenges. During a second visit, swimmers performed a usual swimming session while lifeguards stayed in the same pool environment for the same time period. Forced expiratory volume in one second (FEV1) was measured before and 5 min after the end of the session. Exhaled breath condensate (EBC) was sampled before and 10 min after the session and EBC 8-IsoP levels were analysed by enzyme immunoassay. Change in EBC 8-IsoP from baseline to post-swimming session was calculated. Results: We observed no relationships between airway hyper-responsiveness and 8-IsoP values before or after swimming in swimmers. The levels of 8-IsoP were significantly higher after the training session (mean value 2.9, s?=?0.5 pg?mL?1) than at baseline (mean value 1.9, s?=?0.4 pg?mL?1) in swimmers only (p?=?.012). EBC 8-IsoP levels after the swimming session significantly correlated with the percent change in FEV1 after swimming. Conclusions: EBC 8-IsoP levels were increased after training in swimmers but not in lifeguards, suggesting that exercise-induced hyperpnoea in a chlorinated pool environment increases airways oxidative stress.  相似文献   

15.
The purpose of this study was to ascertain the typical metabolic power characteristics of elite men’s hockey, and whether changes occur within matches and throughout an international tournament. National team players (n = 16), divided into 3 positional groups (strikers, midfielders, defenders), wore Global Positioning System devices in 6 matches. Energetic (metabolic power, energy expenditure) and displacement (distance, speed, acceleration) variables were determined, and intensity was classified utilising speed, acceleration and metabolic power thresholds. Midfielder’s average metabolic power (11.8 ± 1.0 W · kg?1) was similar to strikers (11.1 ± 1.3 W · kg?1) and higher than defenders (10.8 ± 1.2 W · kg?1, P = 0.001). Strikers (29.71 ± 3.39 kJ · kg?1) expended less energy than midfielders (32.18 ± 2.67 kJ · kg?1, P = 0.014) and defenders (33.23 ± 3.96 kJ · kg?1, P < 0.001). Energetic variables did not change between halves or across matches. Across all positions, over 45% of energy expenditure was at high intensity (>20 W · kg?1). International hockey matches are intense and highly intermittent; however, intensity is maintained throughout matches and over a tournament. In isolation, displacement measures underestimate the amount of high-intensity activity, whereas the integration of instantaneous speed and acceleration provides a more comprehensive assessment of the demands for variable-speed activity typically occurring in hockey matches.  相似文献   

16.
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17.
Purpose: To develop models to estimate aerobic fitness (VO2max) from PACER performance in 10- to 18-year-old youth, with and without body mass index (BMI) as a predictor. Method: Youth (N = 280) completed the PACER and a maximal treadmill test to assess VO2max. Validation and cross-validation groups were randomly formed to develop and examine accuracy of models. Participants were classified into FitnessGram® Healthy Fitness Zone categories based on measured and estimated VO2max and criterion-referenced validity was evaluated. Results: Multiple correlations between measured and estimated VO2max ranged from .70 to .73, with standard errors of estimate between 6.43 and 6.68 mL·kg?1·min?1. Accuracy with and without BMI was nearly identical. Overall, criterion-referenced validity evidence was moderate. Conclusion: Moderately accurate and feasible models were developed. Minimal improvement in accuracy was noted when BMI was added as a predictor. The model with PACER and age as predictors has a high level of utility for youth fitness testing.  相似文献   

18.
Background: A student’s choice to engage in a learning task is highly related to the student’s environmental stimuli and his or her perception of interest. From this perspective, the construct of situational interest (SI) has been used to interpret students’ motivation in task engagement. SI is assumed to be transitory, environmentally activated, and context specific. It has been conceptualized as a multidimensional construct with five dimensions: instant enjoyment, exploration intention, attention demand, novelty, and challenge. Few prior studies have compared SI between girls and boys in physical education (PE) contexts, and these studies have offered contrasting findings. They were conducted in coeducational (coed) or single-sex contexts and used learning tasks centred on a variety of outcomes: technical or tactical skills, creativity and cultural understanding.

Purpose: In the context of the debate on single-sex and coed classes in PE, this study aimed to estimate the effects of single-sex and coed PE classes on students’ situational interest (SI) within learning tasks centred on technical skills. The researchers decided to study learning tasks centred on the development of students’ technical skills, since these tasks are often used by teachers in PE.

Participants: The sample consisted of 177 Swiss secondary school students, aged 11–17 years (M?=?14.07, SD?=?1.41, 96 boys, 81 girls).

Data collection: The students completed the French 15-item SI Scale after practising a technical learning task in single-sex and coed PE contexts. The researchers chose five physical activities (i.e. athletics, basketball, dance, gymnastics, and volleyball), which are commonly taught in the state of Vaud (Switzerland) and provide a balance between masculine and feminine activities.

Data analysis: A two-way repeated-measures MANOVA was performed to examine the main and interaction effects of student sex and class sex composition on the five SI dimensions.

Findings: The results showed a main effect of class sex composition on student SI but no main effect of student sex and no interaction effect of student sex and class sex composition. More precisely, the scores for three SI dimensions (i.e. instant enjoyment, exploration intention, and attention demand) were higher in the coed context than in the single-sex context.

Conclusions: This study encourages teachers to propose coed PE classes to enhance students’ motivation and engagement when practising learning tasks centred on technical skills. This study offers supplementary evidence of the teacher’s role in promoting student SI. Beyond accounting for students’ dispositional factors (e.g. sex), PE teachers can significantly impact students’ SI in technical learning tasks through instructional choices.  相似文献   

19.
ABSTRACT

Purpose: The purposes of the present study were to (a) compare context-specific conceptions of friendship quality in youth sport and music, and (b) determine how friendship quality is related to motivational beliefs in sport and music. Method: Adolescents (N = 366; Mage = 12.9, SD = 1.0) who were involved in both organized sport and music completed measures of domain-specific friendship quality, perceived competence, enjoyment, anxiety, and motivational orientation. Results: For purpose one, a repeated-measures MANOVA revealed that (a) boys and girls rated their best sport friends higher in self-esteem enhancement and supportiveness than their best music friends, (b) boys rated their best sport friends higher in loyalty and intimacy, things in common, companionship and pleasant play, and conflict resolution than their best music friends, (c) girls rated positive friendship quality dimensions higher than boys, and (d) there were no domain or gender differences in friendship conflict. For purpose two, structural equation modeling revealed that (a) for sport, positive friendship quality dimensions were directly associated with perceived competence and indirectly associated with enjoyment, anxiety, and motivational orientation, and (b) for music, positive friendship quality and friendship conflict were related to competence motivation variables. Conclusion: Collectively, findings indicate domain differences in friendship quality and the relationship between friendship quality and motivational outcomes in sport and music. Despite some domain differences, findings demonstrate the significance of friendship quality for adolescents involved in sport and music.  相似文献   

20.
Purpose: Suprapostural task performance (manual tracking) and postural control (sway and frequency) were examined as a function of attentional focus, age, and tracking difficulty. Given the performance benefits often found under external focus conditions, it was hypothesized that external focus instructions would promote superior tracking and reduced postural sway for both age groups, most notably as a function of tracking difficulty. Method: Postural sway, frequency of postural adjustments, and tracking accuracy under two levels of task difficulty were assessed for younger (M age = 20.98 years) and older (M age = 70.80 years) participants while they manually tracked a pursuit-rotor target. Participants received instructions to focus on either their actions (internal focus) or the effect of their actions (external focus). Results: Analyses revealed a beneficial effect of an external focus on suprapostural performance on the less-difficult (0.5 Hz) tracking task, and this performance was associated with a modest improvement in medial-lateral postural sway. Conclusion: The findings offer limited support for external focus-of-attention benefits under a mildly challenging tracking task. While older adults tend to adopt a conservative postural control strategy regardless of tracking task difficulty, external focus instructions on a suprapostural task promoted a modest, beneficial shift in postural control.  相似文献   

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