Does the intensity of daily walking matter for protecting against the development of a slow gait speed in people with or at high risk of knee osteoarthritis? An observational study.

OBJECTIVE: Knee osteoarthritis (OA) is a risk factor for a decline in gait speed. Daily walking reduces the risk of developing slow gait speed and future persistent functional limitation. However, the protective role of walking intensity is unclear. We investigated the association of substituting time spent not walking, with walking at light and moderate-to-vigorous intensities for incident slow gait over 2-years, among people with or at high risk of knee OA. METHOD: We used baseline and 2-year follow-up data from the Multicenter Osteoarthritis (MOST) study (n = 1731) and the Osteoarthritis Initiative (OAI, n = 1925). Daily walking intensity was objectively assessed using accelerometer-enabled devices, and classified as; not walking (<1 steps/min), very-light (1-49 steps/min), light (50-100 steps/min), and moderate-to-vigorous (>100 steps/min). We defined slow gait during a 20-m walk, as <1 m/s and <1.2 m/s. Isotemporal substitution evaluated time-substitution effects on incident slow gait outcomes at 2-years. RESULTS: Replacing 20 min/day of not walking with walking at a moderate-to-vigorous intensity, demonstrated small to moderate reductions in the risk of developing a gait speed <1.0 m/s (Relative Risk [95% confidence interval (CI)]; MOST = 0.51 [0.27, 0.98], OAI = 0.21 [0.04, 0.98]), and <1.2 m/s (MOST = 0.73 [0.53, 1.00], OAI = 0.65 [0.36, 1.18]). However, only risk reductions for <1.0 m/s met statistical significance. Replacing not walking with very-light or light intensity walking was not associated with the risk of developing slow gait outcomes. CONCLUSION: When possible, walking at a moderate-to-vigorous intensity (>100 steps/min) may be best recommended in order to reduce the risk of developing critical slow gait speed among people with, or at high risk of knee OA.

A test of basic psychological needs theory in young soccer players: time-lagged design at the individual and team levels.

Within the framework of basic psychological needs theory (Deci & Ryan, 2000), multilevel structural equation modeling (MSEM) with a time-lagged design was used to test a mediation model examining the relationship between perceptions of coaches' interpersonal styles (autonomy supportive and controlling), athletes' basic psychological needs (satisfaction and thwarting), and indicators of well-being (subjective vitality) and ill-being (burnout), estimating separately between and within effects. The participants were 597 Spanish male soccer players aged between 11 and 14 years (M = 12.57, SD = 0.54) from 40 teams who completed a questionnaire package at two time points in a competitive season. Results revealed that at the individual level, athletes' perceptions of autonomy support positively predicted athletes' need satisfaction (autonomy, competence, and relatedness), whereas athletes' perceptions of controlling style positively predicted athletes' need thwarting (autonomy, competence, and relatedness). In turn, all three athletes' need satisfaction dimensions predicted athletes' subjective vitality and burnout (positively and negatively, respectively), whereas competence thwarting negatively predicted subjective vitality and competence and relatedness positively predicted burnout. At the team level, team perceptions of autonomy supportive style positively predicted team autonomy and relatedness satisfaction. Mediation effects only appeared at the individual level.

Changes in work affect in response to lunchtime walking in previously physically inactive employees: A randomized trial.

Physical activity may regulate affective experiences at work, but controlled studies are needed and there has been a reliance on retrospective accounts of experience. The purpose of the present study was to examine the effect of lunchtime walks on momentary work affect at the individual and group levels. Physically inactive employees (N = 56; M age = 47.68; 92.86% female) from a large university in the UK were randomized to immediate treatment or delayed treatment (DT). The DT participants completed both a control and intervention period. During the intervention period, participants partook in three weekly 30-min lunchtime group-led walks for 10 weeks. They completed twice daily affective reports at work (morning and afternoon) using mobile phones on two randomly chosen days per week. Multilevel modeling was used to analyze the data. Lunchtime walks improved enthusiasm, relaxation, and nervousness at work, although the pattern of results differed depending on whether between-group or within-person analyses were conducted. The intervention was effective in changing some affective states and may have broader implications for public health and workplace performance.

Role of sports psychology and sports nutrition in return to play from musculoskeletal injuries in professional soccer: an interdisciplinary approach.

Musculoskeletal injuries are prevalent in professional soccer and can result in lost training time or match play. It is intuitive that the "return to play" (RTP) pathway will depend, in large part, on the expertise of sports medicine practitioners (e.g. surgeons, physicians, physiotherapists) responsible for player's recovery. Consensus statements on returning athletes to sport following injury acknowledge the contributions of sport psychology and sports nutrition. However, specific consideration on how to integrate these two recognized - but often overlooked components of injury rehabilitation - into existing sport medicine approaches has yet to be examined. Using a framework of milestones directed by the medical physician and physical trainer, the evidence is summarized and suggestions provided on the integration of sports psychology and sports nutrition into an interdisciplinary RTP approach. We examine recovery from a phase approach (acute injury and functional recovery) to highlight interdisciplinary opportunities in the management of musculoskeletal soccer injuries. An interdisciplinary approach is understood to achieve outcomes that could not be achieved within the framework of a single discipline. The incorporation of sports psychology and nutrition theoretically compliment milestones used in current medically-based RTP models. Our hope is that this article serves as a catalyst for interdisciplinary practice and research - not only in sports nutrition and sports psychology - but across all sport and exercise disciplines.

Effects of a programme of vigorous physical activity during secondary school physical education on academic performance, fitness, cognition, mental health and the brain of adolescents (Fit to Study): study protocol for a cluster-randomised trial.

BACKGROUND: Early adolescence is a period of dynamic neurobiological change. Converging lines of research suggest that regular physical activity (PA) and improved aerobic fitness have the potential to stimulate positive brain changes, improve cognitive function and boost academic attainment in this age group, but high-quality studies are needed to substantiate these findings. The primary aim of the Fit to Study trial is to investigate whether short infusions of vigorous PA (VPA) delivered during secondary school physical education (PE) can improve attainment in maths, as described in a protocol published by NatCen Social Research. The present protocol concerns the trial's secondary outcome measures, which are variables thought to moderate or mediate the relationship between PA and attainment, including the effect of the intervention on cardiorespiratory fitness, cognitive performance, mental health and brain structure and function. METHOD: The Fit to Study project is a cluster-randomised controlled trial that includes Year 8 pupils (aged 12-13) from secondary state schools in South/Mid-England. Schools were randomised into an intervention condition in which PE teachers delivered an additional 10 min of VPA per PE lesson for one academic year, or a 'PE as usual' control condition. Intervention and control groups were stratified according to whether schools were single-sex or co-educational. Assessments take place at baseline (end of Year 7, aged 11-12) and after 12 months (Year 8). Secondary outcomes are cardiorespiratory fitness, objective PA during PE, cognitive performance and mental health. The study also includes exploratory measures of daytime sleepiness, attitudes towards daily PA and PE enjoyment. A sub-set of pupils from a sub-set of schools will also take part in a brain imaging sub-study, which is embedded in the trial. DISCUSSION: The Fit to Study trial could advance our understanding of the complex relationships between PA and aerobic fitness, the brain, cognitive performance, mental health and academic attainment during adolescence. Further, it will add to our understanding of whether school PE is an effective setting to increase VPA and fitness, which could inform future PA interventions and education policy. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03286725 . Retrospectively registered on 18 September 2017. ClinicalTrials.gov, NCT03593863 . Retrospectively registered on 19 July 2018.

Predicting migration of trace amounts of styrene in poly(styrene) below the glass transition temperature.

The use of general purpose polystyrene (GPPS) as food packaging material is widespread. Therefore, the rate of migration of the styrene in GPPS is of interest in order to predict the potential exposure of consumers to styrene. Studies have shown a relatively weak dependence of the diffusion coefficient on the residual styrene content, and a strong dependence on temperature. We have compared the predictions of the free-volume theory with experimentally measured diffusivity data. The predictions and the measured values are observed to be consistent with each other. These results illustrate the capability of the free-volume theory of transport to predict the diffusivity of trace amounts of impurity in a glassy polymer.

In vitro simulation of contact fatigue damage found in ultra-high molecular weight polyethylene components of knee prostheses.

An in vitro simulation of fatigue loading of ultra-high molecular weight polyethylene (UHMWPE) knee components was carried out on a knee simulator and on a rolling and sliding wear tester. Tibial components for the knee simulator were gamma-sterilized, implantable components taken from manufacturing inventory. The rolling/sliding UHMWPE discs were machined from bar stock and either gamma sterilized in air and accelerated aged, or left as non-sterilized (controls). Cracking and delamination of samples that had been gamma sterilized in air and aged were observed in both types of tests. Contact fatigue damage was visible in as few as 150,000 cycles using the knee simulator at loads of 122 N (275 1b). The rolling/sliding samples showed signs of damage in as few as 130,000 cycles with an estimated stress of 15 MPa and 25 per cent sliding. However, cracking and delamination were not generated in the never-sterilized or recently sterilized controls. UHMWPE that has been gamma sterilized in air and aged is shown to be susceptible to contact fatigue damage. These results are important to the interpretation of in vitro total knee replacement simulations used to assess the performance of tibial bearings.

Perceived barriers to exercise among adolescents.

In this study, the authors identify differences in barriers to exercise among high school students (n = 236) according to gender and self-reported levels of physical activity. Major barriers to exercise were "time constraints," "unsuitable weather," "school and schoolwork," and "lack of interest or desire." Univariate ANOVAs revealed adolescent males had significantly higher scores than females for "use of alcohol and drugs" and "having a girlfriend," while "time constraints" was a significantly greater barrier to exercise among females. Discriminant analyses indicated the barriers of "having a girlfriend" and "use of alcohol and drugs" also distinguished highly active males from highly active females. Results are discussed and suggestions are offered concerning how to reduce perceived barriers to exercise among adolescents.

Predictors of personal investment in physical activity among middle-aged and older adults.

The purpose of this study was to determine the relationship between the social psychological components of Personal Investment Theory and exercise behaviors among 47 middle-aged and older men and women participating in an organized exercise program. Specifically, the degree to which personal incentives for exercise, perceptions of sense of self (i.e., physical self-efficacy, fitness locus of control, self-motivation, social identity), and the congruence between program and participants' goals predict present physical activity and estimated future physical activity was examined. Multiple regression analyses indicated that present and future exercise behaviors significantly related to social psychological variables reflecting personal investment.

An exploratory examination of the Parent-initiated Motivational Climate Questionnaire.

The purpose of this study was to examine the factor structure and internal reliability of the Parent-initiated Motivational Climate Questionnaire among 112 boys and 98 girls, young adolescents, and older adolescents. The questionnaire had a meaningful 3-factor structure and showed acceptable internal reliability. There was a significant difference between how boys and girls perceived their parents' reactions to their learning new physical skills. In contrast to boys, girls thought that both their mothers and fathers focused on improvement and self-satisfaction during the learning process and deemphasized learning without effort and worrying about making mistakes. Age did not significantly affect the perceptions the individuals had of their parents' convictions about their learning in the physical domain.

Personal investment predictors of life satisfaction among physically active middle-aged and older adults.

The purpose of this study was to determine the relationship between the social psychological components of personal investment and life satisfaction among 85 middle-aged and older men and women participating in a structured exercise program. Specifically, we examined the degree to which personal incentives for exercise, perceptions of a sense of self, and the congruency between the exercise program and the participants' goals, predicted life satisfaction. Multiple regression analyses revealed that the social psychological variables reflecting personal investment accounted for 52% of the variance for life satisfaction in physically active middle-aged and older adults. The personal investment theory is supported as a framework for investigating psycho-social predictors of situational outcomes such as life satisfaction.

A developmental examination of children's understanding of effort and ability in the physical and academic domains.

The purpose of this study was to test one aspect of the developmental component of Nicholls' theory of achievement motivation. Specifically, we examined and contrasted children's levels of understanding of effort and ability in the physical and academic domains. Students (N = 144; 8 boys and 8 girls for each age group from the ages of 5-13 years) participated in two sessions; in each they viewed two films and responded to questions posed in a subsequent structured interview. The films showed two children applying unequal effort which resulted in two possible outcomes: (1) the children achieved the same score; or (2) the lazier child outscored the hard-working child. A developmental-structural analysis of the children's responses was conducted, and the same four levels of understanding of effort and ability identified by Nicholls (1978) emerged. In addition, a fifth level (i.e., Level 0) was included which represented children who were unable to identify the hard-working student in the films or whose responses did not address the effort-ability issue. A nonparametric test of association between ordinal variables revealed a positive and significant relationship between children's ages and their levels of understanding of ability in both contexts. Children's conceptions of ability were significantly correlated across domains. No gender differences were evident in children's understanding of effort and ability in either the physical or academic contexts.

Multi-sample confirmatory factor analysis of the Task and Ego Orientation in Sport Questionnaire.

The Task and Ego Orientation in Sport Questionnaire (TEOSQ; Duda, 1989; Duda & Nicholls, 1992) was designed to assess individual differences in the proneness for task and ego involvement in athletic settings. The purpose of this study was to independently and simultaneously test the measurement model assumed to underlie the TEOSQ across intercollegiate athletes (n = 143), college students enrolled in skill classes (n = 270), high school athletes (n = 310), and junior high school sport participants (n = 234). Single-sample confirmatory factor analysis (CFA) was employed to establish and to evaluate the tenability of a baseline model in terms of each sample. A series of multi-sample CFAs were then conducted to test the invariance of the measurement and factor structure of the TEOSQ across the four groups. The measures of overall fit for the hypothetical two-factor structure of the TEOSQ were generally acceptable, albeit weaker in the case of the college students. Further, the results of the multi-sample CFA did not support the assumption for intergroup invariance of the TEOSQ. This finding indicated that the 13 items and structure of the TEOSQ were not equally valid across the present four samples.

Personal investment predictors of adolescent motivational orientation toward exercise.

The primary purpose of this study was to determine the relationship between the psychosocial components of Personal Investment Theory and exercise behavior among 237 adolescents. Specifically, the adolescents' personal incentives for exercise, perceptions of sense of self, and perceived options for exercise were examined as predictors of physical activity level. A secondary purpose was to determine the interdependence between the components reflecting personal investment and self-reported exercise behavior separately by gender and activity level. Multiple regression analysis revealed that the personal investment variables accounted for 19% of the variance in exercise behavior among male adolescents and 25% of the variance in exercise behavior among female adolescents. Discriminant analysis correctly classified 76.5% of the males and 71.8% of the females as well as 80.4% of high-active adolescents and 73.3% of low-active adolescents on the basis of the three meaning components. Further, the results indicated that the significant predictors of exercise behavior varied as a function of gender as well as the adolescents' level of physical activity.

The relationship of task and ego orientation to sportsmanship attitudes and the perceived legitimacy of injurious acts.

Nicholls's theory of achievement motivation (1989) assumes one's goal orientation in an achievement activity is consistent with one's views concerning what is acceptable behavior in that setting. The purpose of this study was to determine the relationship of a task and ego goal orientation (i.e., the tendency to focus on personal mastery or beating others, respectively) to sportsmanship attitudes and perceptions of the legitimacy of aggressive acts by testing this assumption in the context of interscholastic sport. Fifty-six male and 67 female high school basketball players completed a three-part questionnaire assessing (a) individual differences in goal orientation, (b) approval of "unsportsmanlike play/cheating," "strategic play," and "sportsmanship behaviors," and (c) subjective ratings of the legitimacy of intentionally injurious behaviors. All measures were basketball-specific. Results indicated a low task orientation and high ego orientation corresponded to an endorsement of unsportsmanlike play/cheating. Ego orientation positively related to the rating of aggressive acts as more legitimate. Gender differences in goal orientation, sportsmanship attitudes, and legitimacy ratings were observed.

Examination of the psychometric properties of the perceived motivational climate in sport questionnaire-2 in a sample of female athletes.

We undertook two studies to determine the validity and reliability of the revised Perceived Motivational Climate in Sport Questionnaire (PMCSQ-2). In Study 1, 201 female athletes (mean age 16.4 years) were administered the initial version of the PMCSQ-2 and a measure of reported tension and pressure experienced in sport. Exploratory principal component analysis suggested that the PMCSQ-2 contained two higher-order scales (Task-Involving and Ego-Involving climates), each with three subscales (Task: Cooperative Learning, Effort/ Improvement, Important Role; Ego: Intra-Team Member Rivalry, Unequal Recognition, Punishment for Mistakes). In Study 2, 385 female volleyball players (mean age 15.2 years) completed the PMCSQ-2, the Intrinsic Motivation Inventory and a measure of Team Satisfaction. Confirmatory factor analysis was applied to six competing models. The oblique six-factor model and oblique hierarchical model provided comparable fit to the data. Acceptable fit was reached based on model respecification. Across Studies 1 and 2, internal consistency was found to be acceptable for the higher-order scales and subscales (with the exception of the Intra-Team Member Rivalry subscale). We found evidence for the concurrent validity of the instrument.

Goal orientations, beliefs about success, and performance improvement among young elite Dutch soccer players.

Extending past work testing goal perspective theory in sport, one purpose of this study was to examine, via a longitudinal design, the relationship of goal orientations to the beliefs about the causes of success in the case of elite male Dutch soccer players. A second purpose was to determine the relationship of goals and beliefs to ratings of performance. Seventy-five male pupils representing five teams from an internationally renowned soccer school in The Netherlands completed the TEOSQ and a measure of their perceptions of the determinants of success in soccer at the onset and conclusion of one season. Assessments of the coaches' appraisal and athletes' self-reported performance in soccer were carried out at the same time. In line with other studies, a positive association between ego orientation and the belief that ability or innate talent are determinants of success was revealed. Task orientation was linked to the beliefs that effort, team play, and parental support contribute to achievement in soccer. An increase in skilled performance over the season (as appraised by the coach) corresponded to a stronger task orientation and the beliefs that soccer success stems from hard work and having supportive parents.

Motivational climate and goal orientations as predictors of perceptions of improvement, satisfaction and coach ratings among tennis players.

One purpose of this work was to study the relationship of goal orientations and the perceived motivational climate created by the coach in relation to 219 competitive Spanish tennis players': a) perceived improvement in different facets of the game, b) satisfaction with their competitive results, overall level of play, and coach, and c) ratings of their coach. The second purpose was to examine whether the dependent variables were best predicted by the perceived situationally emphasized goal structure created by the coach and/or the athletes' dispositional goal perspective. Intermediate (N=70), advanced (N=124), and professional (N=25) level players completed Spanish versions of the TEOSQ and the PMCSQ-2 and items assessing perceived improvement specific to tennis, satisfaction and coach ratings. The results were consistent with the tenets of goal perspective theory and provide further support for the promotion of a task involving atmosphere in sport.