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The purpose of this investigation was to examine the factorial validity and measurement invariance of the short version of the Leadership Scale for Sports (LSS; Chelladurai & Saleh, 1980): coaches' perceptions of their own behavior, athletes' preferences and athletes' perceptions of their coaches' behavior. This validation will allow researchers to minimize time demands on participants. Three independent samples of athletes ( n 1  = 373; n 2  = 817; n 3  = 246) and two samples of coaches ( n 1  = 115; n 2  = 351) were studied to examine the factorial validity and measurement invariance of the 25-item version of the LSS (LSS-25; Chiu et al., 2016). Findings indicated that a 15-item version (LSS-15) fits the data better than the LSS-25. The LSS-15 showed factorial validity and proved to have adequate reliability, convergent validity and discriminant validity. Multiple-group confirmatory factor analysis showed that its factor structure was invariant across two independent samples and across gender for athletes' perceived and preferred versions. Significant relationships between the LSS-15 subscales and athlete satisfaction also demonstrate criterion validity. These findings support a valid and reliable alternative to the original LSS long-form, especially in applied settings when time constraints require a brief measure of leadership or when study designs include multiple variables.

Background: Nowadays, doping is not confined to elite sport, it is also spread throughout gymnasia and fitness centers, and it is seen as a public health concern. Studies focusing on performance-enhancing substances (PES) use among gym users are few and mostly concern the practice of bodybuilding and the use of anabolic-androgenic steroids (AAS), without providing information about social indicators to further explore why this specific population use these substances. Objectives: To investigate the extent of PES use and examine the way social indicators, exercise profile and gym modalities influence the use of these substances among a sample of gym users. Methods: Cross-sectional descriptive study, among a convenience sample of 453 Portuguese gym users, recruited directly by five institutional gyms´ email and Facebook. Data were collected via a structured web-based survey, between October and November 2017. Multiple binary logistic regression, the Chi-Square test or Monte Carlo Simulation or Fisher's Exact test were used. The odds ratios and their respective 95% confidence intervals were calculated. Results: 11,1% of gym users reported the use of prohibited PES, which varies significantly according to gender, education, exercise profile and type of practice. Gender was associated with the class of PES used. Polypharmacy was a common practice among users, increasing the risk of side-effects. Peer effect and media appear to be strikingly important in the misuse of PES. Conclusion: Results provide precise insight into the specific factors associated with PES use, which could support prevention strategies in gym/fitness context.

Drawing from the model of parental involvement in sport, the overall purpose was to examine the associations of perceptions of parenting practices (encouragement, reinforcement, instruction, and role modeling) and athletes' psychological variables (self-efficacy, social self-efficacy, self-regulation, and intrinsic motivation) of elite and sub-elite youth athletes. Participants were elite ( n = 210) and sub-elite ( n = 635) athletes aged between 14 and 18 years ( M age = 16.58, SD = 1.33). Structural equation modeling analysis revealed that young elite athletes' perceptions of sport-related parenting practices are associated with their psychological skills and performance level in sport. Specifically, in comparison with their sub-elite peers, perceptions of parental encouragement had a significantly different strong effect on intrinsic motivation. Moreover, perceptions of parental modeling revealed different effects on performance level, as well as on intrinsic motivation, and self-regulation. These perceptions of parenting practices may promote a positive learning environment, resulting in an increased likelihood of achieving a high level of sport performance in comparison with their sub-elite peers.

This study reports on outcomes from a behavioral obesity treatment program, evaluating if treatment-related changes in body image and psychological well-being are predictors of weight change during treatment and after follow-up. Participants were 142 overweight/obese women (BMI=30.2+/-3.7kg/m(2); age=38.3+/-5.8 years) participants in a behavioral treatment program consisting of a 4-month treatment period and a 12-month follow-up. Psychosocial variables improved during treatment and these changes were correlated with 4-month weight reduction. Short-term changes in body size dissatisfaction (p=.002) and mood (p=.003) predicted long-term weight loss. Additional results suggest that there might be a predictive role of short-term changes in body size dissatisfaction and self-esteem on long-term weight loss after accounting for initial weight change (p<.028). We conclude that, along with weight changes, cognitive and affect-related processes influenced during obesity treatment may be related long-term success, in some cases independently of initial weight loss., (2010 Elsevier Ltd. All rights reserved.)

Ecological dynamics characterizes adaptive behavior as an emergent, self-organizing property of interpersonal interactions in complex social systems. The authors conceptualize and investigate constraints on dynamics of decisions and actions in the multiagent system of team sports. They studied coadaptive interpersonal dynamics in rugby union to model potential control parameter and collective variable relations in attacker-defender dyads. A videogrammetry analysis revealed how some agents generated fluctuations by adapting displacement velocity to create phase transitions and destabilize dyadic subsystems near the try line. Agent interpersonal dynamics exhibited characteristics of chaotic attractors and informational constraints of rugby union boxed dyadic systems into a low dimensional attractor. Data suggests that decisions and actions of agents in sports teams may be characterized as emergent, self-organizing properties, governed by laws of dynamical systems at the ecological scale. Further research needs to generalize this conceptual model of adaptive behavior in performance to other multiagent populations.

Background: Changes in body image and subjective well-being variables (e.g. self-esteem) are often reported as outcomes of obesity treatment. However, they may, in turn, also influence behavioral adherence and success in weight loss. The present study examined associations among obesity treatment-related variables, i.e., change in weight, quality of life, body image, and subjective well-being, exploring their role as both mediators and outcomes, during a behavioral obesity treatment., Methods: Participants (BMI = 31.1 +/- 4.1 kg/m2; age = 38.4 +/- 6.7 y) were 144 women who attended a 12-month obesity treatment program and a comparison group (n = 49), who received a general health education program. The intervention included regular group meetings promoting lasting behavior changes in physical activity and dietary intake. Body image, quality of life, subjective well-being, and body weight were measured at baseline and treatment's end. Mediation was tested by multiple regression and a resampling approach to measure indirect effects. Treatment group assignment was the independent variable while changes in weight and in psychosocial variables were analyzed alternatively as mediators and as dependent variables., Results: At 12 months, the intervention group had greater weight loss (-5.6 +/- 6.8% vs. -1.2 +/- 4.6%, p < .001) and larger decreases in body size dissatisfaction (effect size of 1.08 vs. .41, p < .001) than the comparison group. Significant improvements were observed in both groups for all other psychosocial variables (effect sizes ranging from .31-.75, p < .05). Mediation analysis showed that changes in body image and body weight were concurrently mediators and outcomes of treatment, suggesting reciprocal influences. Weight loss partially mediated the effect of treatment on quality of life and on self-esteem but the reciprocal effect was not observed., Conclusion: Changes in weight and body image may reciprocally affect each other during the course of behavioral obesity treatment. No evidence of reciprocal relationships was found for the other models under analysis; however, weight changes partially explained the effects of treatment on quality of life and self-esteem. Weight and psychosocial changes co-occur during treatment and will probably influence each other dynamically, in ways not yet adequately understood. Results from this study support the inclusion of intervention contents aimed at improving body image in weight management programs.

Previous work on dynamics of interpersonal interactions in 1 vs. 1 sub-phases of basketball has identified changes in interpersonal distance between an attacker and defender as a potential control parameter for influencing organizational states of attacker-defender dyads. Other studies have reported the constraining effect of relative velocity between an attacker and defender in 1 vs. 1 dyads. To evaluate the relationship between these candidate control parameters, we compared the impact of both interpersonal distance and relative velocity on the pattern-forming dynamics of attacker-defender dyads in the sport of rugby union. Results revealed that when interpersonal distance achieved a critical value of less than 4 m, and relative velocity values increased or were maintained above 1 m x s(-1), a successful outcome (i.e. clean attempt) for an attacker was predicted. Alternatively, when values of relative velocity suddenly decreased below this threshold, at the same critical value of interpersonal distance, a successful outcome for the defender was predicted. Data demonstrated how the coupling of these two potential, nested control parameters moved the dyadic system to phase transitions, characterized as a try or a tackle. Observations suggested that relative velocity increased its influence on the organization of attacker-defender dyads in rugby union over time as spatial proximity to the try line increased.

Background: This study was conceived to analyze how exercise and weight management psychosocial variables, derived from several health behavior change theories, predict weight change in a short-term intervention. The theories under analysis were the Social Cognitive Theory, the Transtheoretical Model, the Theory of Planned Behavior, and Self-Determination Theory., Methods: Subjects were 142 overweight and obese women (BMI = 30.2 +/- 3.7 kg/m2; age = 38.3 +/- 5.8 y), participating in a 16-week University-based weight control program. Body weight and a comprehensive psychometric battery were assessed at baseline and at program's end., Results: Weight decreased significantly (-3.6 +/- 3.4%, p < .001) but with great individual variability. Both exercise and weight management psychosocial variables improved during the intervention, with exercise-related variables showing the greatest effect sizes. Weight change was significantly predicted by each of the models under analysis, particularly those including self-efficacy. Bivariate and multivariate analyses results showed that change in variables related to weight management had a stronger predictive power than exercise-specific predictors and that change in weight management self-efficacy was the strongest individual correlate (p < .05). Among exercise predictors, with the exception of self-efficacy, importance/effort and intrinsic motivation towards exercise were the stronger predictors of weight reduction (p < .05)., Conclusion: The present models were able to predict 20-30% of variance in short-term weight loss and changes in weight management self-efficacy accounted for a large share of the predictive power. As expected from previous studies, exercise variables were only moderately associated with short-term outcomes; they are expected to play a larger explanatory role in longer-term results.

In previous attempts to identify dynamical systems properties in patterns of play in team sports, only 2-D analysis methods have been used, implying that the plane of motion must be preselected and that movements out of the chosen plane are ignored. In the present study, we examined the usefulness of 3-D methods of analysis for establishing the presence of dynamical systems properties, such as phase transitions and symmetry-breaking processes in the team sport of rugby. Artificial neural networks (ANNs) were employed to reconstruct the 3-D performance space in a typical one-versus-one subphase of rugby. Results confirm that ANNs are reliable tools for reconstructing a 3-D performance space and may be instrumental in identifying pattern formation in team sports generally.