Variability has long been used as an indication of stability in the application of a dynamical systems approach to human motion (i.e., greater variability has been related to a less stable system and vise versa). This paper incorporates the probability of gait transition during walking and running at a certain speed to represent the stability of human locomotion. The mathematical representation concerning the probability of gait transition change with locomotory speed was derived for increasing walking speed and decreasing running speed. Additionally, the influence of acceleration and deceleration on the stability landscapes of walking and running was discussed based on experimental data. The influence of acceleration was also used to explain the different trends of hysteresis observed by various researchers. Walk-to-run transition speed was greater than run-to-walk transition speed, with a greater magnitude of acceleration, while the trend was reversed with a lesser acceleration magnitude. The quantitative measure of the relationship between variability and stability needs to be explored in the future.
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Yilin Li and Weidong Li
Purpose: The authors conducted a comprehensive review of the literature on caring in physical education and physical activity settings with a goal of identifying the status, gaps, and future trends of research on ethic of care in our field. Methods and Data Analysis: The authors identified and coded 16 peer-reviewed and data-based articles with a coding template from six databases. For each of the coding categories, frequencies and percentages were calculated. Results: Physical education teachers valued the importance of being caring. The perceived caring climate or perception of caring behaviors was positively related to a number of motivational, cognitive, and emotional variables in physical education or physical activity settings. Discussion and Conclusion: Research on caring in our field is still in its infancy. Noddings argues that caring is the end in and of itself. This philosophical belief of caring as an end in and of itself needs further examination. The review of literature showed that the majority of studies had solely focused on caring as a means to an end. This is misaligned with the work of Noddings. More experimental research with a rigorous design and appropriate statistical modeling for data analysis are needed. Future research shall also examine other students’ behaviors and learning outcome variables. The teaching pedagogies and practices identified in these qualitative studies can help guide physical education teachers to enact a caring-based curriculum.
Athletics-related professional associations are nonprofit and formed voluntarily by athletic administrators or coaches. Because membership enrollment and retention are critical to organizational survival, factors affecting members’ participation should be studied to aid managerial decisions. This study was designed to test a conceptual model and develop a valid Membership Incentive Scale (MIS) to identify important membership incentives. The MIS is based on an underlying theoretical framework and empirical support. Participants (N = 415) from 15 professional associations completed a national survey. The results of factor and data analyses supported the four-factor (Utilitarian, Purposive, Solidary, Informative) incentive model, demonstrated the factorial validity and internal-consistency reliability of the 14-item MIS, and explored the most important factor (Informative Incentives). This article provides an important tool for managers to use to access essential membership incentives for the associations studied, as well as a reference for further studies of membership incentives for these and other organizations.
Twelve organizational variables that were associated with the organizational effectiveness of spare-time sports schools in China were examined. Specifically, coaches' expressed satisfaction with their jobs and their performance was assessed, and the significant organizational correlates of these two effectiveness indicators were identified. Six hundred forty coaches participated in the study, Stepwise multiple regression analyses were carried out to determine if there were common determinants of coaches' job satisfaction and performance, The results showed that job influence, job motivation, incentive system, and leader behavior had a more pervasive influence on job satisfaction and job performance of the coaches than did other variables.
This study was designed to examine the relationship between conceptions of ability and understandings of the meaning of effort. Participants practiced a novel task and completed an ability conceptions questionnaire prior to instruction and a meaning of effort survey after practicing the task. The majority of participants believed in the efficacy of effort, no matter what view of ability they endorsed. Partial support was provided for the proposition that participants with stronger incremental views of ability were likely to endorse the view that trying hard allowed them to fully use their ability. It is suggested that, to promote active engagement and enhance skill learning, teachers capitalize on the belief in the efficacy of effort by focusing their motivational strategies on students’ effort.
This study investigated the possible role of the corticospinal system during force generation and force relaxation. Nine young and healthy subjects were instructed to produce a total force with four fingers within a hand following a preset force generation and relaxation ramp template closely. Excitability of corticospinal (CS) projections was assessed by single- and paired-pulse TMS. Errors introduced by a finger force were partially compensated by other finger forces during force generation, but were amplified during force relaxation. The CS excitability was greater during force generation than maintenance or relaxation. No difference in intracortical inhibition or facilitation was found. Nonnormalized finger extensor EMG responses remained unchanged. The findings suggest that force relaxation is not just a withdrawal from activation, and multifinger interactions are likely controlled beyond the primary motor cortex.
The predictive power of three intersecting environmental dimensions (built structures, social infrastructure, and social capital) on late-life walking was investigated, conceptually based on the ecological framework of place, which posits that a living environment is simultaneously a physical place, a social place, and a set of social bonds. Multilevel models were used to examine the extent to which environments, defined as interactions of the social and material environmental dimensions, reliably predicted walking for transportation among U.S. adults aged 60 years or older in the 2015 National Health Interview Survey (n = 11,180). Random intercepts representing 221 environments showed an intraclass correlation of 21%, indicating high levels of between-environment variance in walking. Social infrastructure had the highest predictive power for walking, followed by material structures and social capital. Synergistic interventions that incorporate the intersecting nature of the sociomaterial environment may be most effective in promoting physical activity in later life.
Graham E. Caldwell and Li Li
In this commentary we question whether the relationship between muscle activity and joint moments is the same for natural motor tasks as for controlled experimental situations. An important consideration in this regard is the identification of the correct electromechanical delay (EMD) for comparing EMG and joint moment data. Data from recent cycling studies are used to illustrate the importance of EMD, and how changing task constraints can alter the relation between muscle activity and joint moment balance for bi-articular antagonist pairs.
Tzai-Li Li and Michael Gleeson
This study compared immunoendocrine responses to a single bout of prolonged cycling at different times of day and to a 2nd bout of cycling at the same intensity on the same day. In a counterbalanced design, 8 men participated in 3 experimental trials separated by at least 4 d. In the afternoon exercise-only trial, subjects cycled for 2 h at 60% VO2max starting at 14:00. In the other 2 trials, subjects performed either 2 bouts of cycling at 60% VO2max for 2 h (starting at 09:00 and 14:00) or a separate resting trial. The single bout of prolonged exercise performed in the afternoon induced a larger neutrophilia and monocy-tosis than the identical bout of morning exercise, possibly the result of reduced carbohydrate availability and the circadian rhythm in cortisol levels. The 2nd prolonged exercise bout caused greater immunoendocrine responses but lower plasma glucose levels and neutrophil function compared with the 1st bout.