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1.
Abstract

The aim of this study was to compare maximal accumulated oxygen deficit (hereafter O2 deficit) estimated from the methods of Whipp et al. (1986 Whipp, B. J., Ward, S. A. and Wasserman, K. 1986. Respiratory markers of the anaerobic threshold. Advances in Cardiology, 35: 4764. [Crossref], [PubMed] [Google Scholar]), Medbo et al. (1988 Medbo, J. I., Mohn, A. C., Tabata, I., Bahr, R., Vaage, O. and Sejersted, O. M. 1988. Anaerobic capacity determined by maximal accumulated O2 deficit. Journal of Applied Physiology, 64: 5060. [PubMed], [Web of Science ®] [Google Scholar]), and Hill et al. (1998 Hill, D. W., Ferguson, C. S. and Ehler, K. L. 1998. An alternative method to determine maximal accumulated O2 deficit in runners. European Journal of Applied Physiology, 79: 114117. [Crossref], [Web of Science ®] [Google Scholar]) to determine whether they agree sufficiently to be used interchangeably. Nineteen moderately to highly trained endurance runners first performed an incremental test to exhaustion for the determination of maximal oxygen uptake ([Vdot]O2max) and peak treadmill speed, followed by six randomly ordered constant-speed tests at 95, 100, 105, 110, 110, and 120% of peak treadmill speed. All tests were separated by at least 72 h and were performed within 4 weeks. The method of Whipp produced an O2 deficit estimate that was lower than that derived from the method of Hill or Medbo (bias ± 95% limits of agreement: ?29.6 ± 36.6 and ?26.1 ± 32.8 ml · kg?1, respectively; P < 0.001). The O2 deficit did not differ between the methods of Hill and Medbo (bias ± 95% limits of agreement: 3.5 ± 41.6 ml · kg?1; n.s.). However, poor correlations (0.21 < r < 0.33; n.s.) together with wide limits of agreement between O2 deficit estimates (70 – 80% of the mean response) clearly question using these methods interchangeably.  相似文献   

2.
Abstract

Oudejans, Bakker, and Beek (2007 Oudejans, R. R. D., Bakker, F. C. and Beek, P. J. 2007. Helsen, Gillis and Weston (2006) err in testing the optical error hypothesis. Journal of Sports Sciences, [Web of Science ®] [Google Scholar]) recognize several relevant aspects of offside judgements in association football in the paper by Helsen, Gilis, and Weston (2006 Helsen, W. F., Gilis, B. and Weston, M. 2006. Errors in judging “offside” in football: Test of the optical error versus the perceptual flash-lag hypothesis. Journal of Sports Sciences, 24: 521528. [Taylor & Francis Online], [Web of Science ®] [Google Scholar]). We agree that the existing knowledge base on offside assessment needs to be expanded for two reasons. First, from a theoretical point of view it is important to examine how assistant referees can learn to deal with the limitations of the human visual information processing system. Second, from a practical point of view it is relevant to understand better refereeing performances and to identify potential explanations for incorrect offside decisions that could impact on the final outcome of the game. Oudejans et al. (2007 Oudejans, R. R. D., Bakker, F. C. and Beek, P. J. 2007. Helsen, Gillis and Weston (2006) err in testing the optical error hypothesis. Journal of Sports Sciences, [Web of Science ®] [Google Scholar]) believe we both misinterpreted the optical error hypothesis and that our data set was unsuited to test it. Below, we react to these comments.  相似文献   

3.
Abstract

The purpose of the present research was to test the applicability of the Dualistic Model of Passion (Vallerand et al., 2003 Vallerand, R. J., Blanchard, C. M., Mageau, G. A., Koestner, R., Ratelle, C.Léonard, M. 2003. Les passions de l'âme: On obsessive and harmonious passion. Journal of Personality and Social Psychology, 85: 756767. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) to being a sport (football) fan. Three studies provided support for this dualistic conceptualization of passion. Study 1 showed that harmonious passion was positively associated with adaptive behaviours (e.g. celebrate the team's victory), whereas obsessive passion was positively associated with maladaptive behaviours (e.g. risking losing one's job to go to a game). Study 2 used a short Passion Scale and showed that harmonious passion was positively related to the positive affective life of fans during the 2006 FIFA World Cup, psychological health (self-esteem and life satisfaction), and public displays of adaptive behaviours (e.g. celebrate the team's victory into the streets), whereas obsessive passion was predictive of maladaptive affective life (e.g. hating opposing teams' fans) and behaviours (e.g. mocking opposing teams' fans). Finally, Study 3 examined the role of obsessive passion as a predictor of partner's conflict that in turn undermined partner's relationship satisfaction. Overall, the present results provided support for the Dualistic Model of Passion. The conceptual and applied implications of the findings are discussed.  相似文献   

4.
Abstract

In learning and development, self-regulation can be described as the extent to which individuals are metacognitively, motivationally, and behaviourally proactive participants in their learning process (Zimmerman, 1989 Zimmerman, B. J. 1989. A social cognitive view of self-regulated academic learning. Journal of Educational Psychology, 81: 329339. [Crossref], [Web of Science ®] [Google Scholar], 2006 Zimmerman, B. J. 2006. “Development and adaptation of expertise: The role of self-regulatory processes and beliefs”. In The Cambridge handbook of expertise and expert performance, Edited by: Ericsson, K. A., Charness, N., Feltovich, P. J. and Hoffman, R. R. 705722. New York: Cambridge University Press. [Crossref] [Google Scholar]). We examined the relationship between self-regulation and performance level in elite (n = 159) and non-elite (n = 285) youth soccer players aged 11–17 years (mean 14.5 years, s = 1.4). The players completed a questionnaire that assessed planning, self-monitoring, evaluation, reflection, effort, and self-efficacy. A logistic regression analysis was performed (controlling for age) to determine which self-regulatory aspects were associated with players' performance level (elite vs. non-elite). High scores on reflection and effort were associated with a higher level of performance. Findings suggest that elite players may be more aware of their strong and weak points as well as better able to translate this awareness into action. In addition, elite players appear to be more willing to invest effort into practice and competition. It is suggested that these better developed self-regulatory skills may translate into a more effective learning environment and ultimately result in an increased capacity for performance in elite players relative to their non-elite peers.  相似文献   

5.
Abstract

Numerous variables influence burnout, one of which is leader–member exchange. The present study was conducted to determine whether leader–member exchange quality affects burnout in professional footballers. The study used the Leader-Member Exchange-7 scale developed by Scandura and Graen (1984 Scandura, T. A. and Graen, G. B. 1984. Moderating effects of initial leader–member exchange status on the effects of a leadership intervention. Journal of Applied Psychology, 69: 428436. [Crossref], [Web of Science ®] [Google Scholar]) to measure leader (coach)–member (player) exchange and Pines's (2005 Pines, A. M. 2005. The burnout measure, short version. International Journal of Stress Management, 12: 7888. [Crossref] [Google Scholar]) abbreviated version of the burnout scale developed by Pines and Aronson (1988 Pines, A. M. and Aronson, E. 1988. Career bumout: Causes and cures, New York: Free Press.  [Google Scholar]) to measure burnout. The data were obtained from the professional players (N = 107) of six football clubs in the Turkish Secondary Football League in western Turkey. The results demonstrated that quality of leader–member exchange significantly and inversely influenced burnout of professional footballers. The study also evaluated quality of leader–member exchange in terms of three strengths of relationship (low, fair, and high) between the coach and players. Contrary to expectations, the results revealed significant differences in burnout when comparing low versus fair quality and low versus high quality, while no significant difference in burnout was observed between fair and high quality.  相似文献   

6.
Abstract

Baldo et al. (2002 Baldo, M. V. C., Ranvaud, R. D. and Morya, E. 2002. Flag errors in soccer games: The flash-lag effect brought to real life. Perception, 31: 12051210. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) and Helsen et al. (2006 Helsen, W., Gilis, B. and Weston, M. 2006. Errors in judging “offside” in association football: Test of the optical error versus the perceptual flash-lag hypothesis. Journal of Sports Sciences, 24: 521528. [Taylor & Francis Online], [Web of Science ®] [Google Scholar]) considered the flash-lag effect to explain errors made by assistant referees when judging offside in association football. The main aims of the present study were as follows: (1) to determine whether the flash-lag effect emerges in offside situations on the field of play or off the field when presented as computer animations or as video footage of real-life matches; (2) to examine offside decision-making errors in two standards of assistant referee – international FIFA and Belgian national referees. The results support the flash-lag hypothesis in several ways. First, both the FIFA and Belgian assistant referees were more likely to make errors by raising their flag when they had to assess offside situations on the field of play and when presented as three-a-side computer animations. Second, more flag errors were made when the defender moved in the opposite direction to that of the attacker. Third, the strategy of raising the flag in case of doubt was not observed when an interpretation of the offside law had to be made about the involvement of play of an attacker. Future research is needed to examine the extent to which on- and off-the-field training sessions can be used as training tools to improve offside decision-making.  相似文献   

7.
8.
Abstract

The aims of this study were twofold: (a) to determine if dispositional achievement goal orientation profiles that are reported in the literature would be observed in a sample of youth athletes, and (b) to examine potential achievement goal orientation profile differences on perceptions of the motivational climate, perceptions of peer relationships, and motivation-related responses. Male soccer players (n = 223) aged 9–12 years (mean = 10.9, s = 0.6) completed a multi-section questionnaire containing assessments of dispositional goal (task, ego) orientations, the perceived task- and ego-involving features of the motivational climate, perceived peer acceptance and friendship quality (positive friendship quality, conflict), perceived ability, soccer enjoyment, and satisfaction with one's performance and the team. Four profiles were observed that closely matched those observed by Hodge and Petlichkoff (2000 Hodge, K. and Petlichkoff, L. 2000. Goal profiles in sport motivation: A cluster analysis. Journal of Sport & Exercise Psychology, 22: 256272. [Crossref], [Web of Science ®] [Google Scholar]), though in the present study a lower proportion of participants exhibited achievement goal profiles consisting of relatively high ego orientation. Achievement goal profile differences were found for all variables except positive friendship quality, with a general trend for those reporting relatively lower task goal orientation to exhibit less adaptive responses. Overall, the findings support achievement goal frameworks (e.g. Nicholls, 1989 Nicholls, J. G. 1989. The competitive ethos and democratic education, Cambridge, MA: Harvard University Press.  [Google Scholar]) and suggest that further examination of dispositional achievement goals may afford a deeper understanding of social relationships and motivational processes in youth sport.  相似文献   

9.
Abstract

Coaching has been recognised as a demanding occupation, associated with a range of stressors. The extent to which coaches perceive stress is likely to be influenced by various personal and situational factors. The purpose of this study was to identify coaches' levels of perceived stress and examine the personal and situational factors that may influence coaches' perceptions of stress. In total, 502 coaches working with university, college, Canada Games, and/or nationally identified athletes completed this study. Coaches completed an online survey, which included questions regarding demographics, work/job-related considerations, and aspects relating to their contract. Coaches also completed the Perceived Stress Scale (Cohen, Kamarck, & Mermelstein, 1983 Cohen, S., Kamarck, T. and Mermelstein, R. 1983. A global measure of perceived stress. Journal of Health and Social Behavior, 24: 385396. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]). Overall coaches indicated slightly below average levels of perceived stress (M = 15.13 out of 40) compared with norm-values (Cohen & Janicki-Deverts, 2012 Cohen, S. and Janicki-Deverts, D. 2012. Who's stressed? Distributions of psychological stress in the United States in probability samples from 1983, 2006, and 2009. Journal of Applied Social Psychology, 42: 13201334. [Crossref], [Web of Science ®] [Google Scholar]). Demographic factors, job-related characteristics, and certain aspects of their contract were associated with coaches' perceptions of stress. In particular, unclear expectations, long-working hours (>40), lack of agreed evaluation criteria, higher salaries, and a lack of social support were related to higher perceptions of stress. As such, the findings of the current study indicate that a reduction in perceived stress is likely to be achieved through a multifaceted approach that addresses multiple factors associated with coaching.  相似文献   

10.
Abstract

The aim of this study was to examine the physiological demands and movement patterns of female basketball players after changes in the rules of the game. Nine varsity players were studied during nine official games. Each game was videotaped to identify the frequencies of the main movements performed, heart rate was recorded continuously, and blood samples were collected to determine blood lactate concentration when the competition rules allowed. The main results showed that the players performed on average 652 ± 128 movements per game, which corresponded to a change in activity every 2.82 s. Mean heart rate was 165 ± 9 beats · min?1 (89.1% of maximum heart rate) for total time and 170 ± 8 beats · min?1 (92.5% of maximum) for live time. Mean blood lactate concentration was 5.2 ± 2.7 mmol · l?1 (55.9% of maximum blood lactate concentration). In addition, heart rates were significantly higher in the first half than the second half of games. These results indicate: (1) a greater physiological load compared with previous studies on female players tested before the rules modification (Beam & Merrill, 1994 Beam, W. C. and Merrill, T. L. 1994. Analysis of heart rates recorded during female collegiate basketball (abstract). Medicine and Science in Sports and Exercise, 26: S66[Crossref] [Google Scholar]; McArdle et al., 1971 McArdle, W., Magel, J. and Kyvallos, L. 1971. Aerobic capacity, heart rate, and estimated energy cost during women's competitive basketball. Research Quarterly, 42: 178186. [PubMed], [Web of Science ®] [Google Scholar]) and (2) lower movement frequencies compared with male players competing under modern rules (Ben Abdelkrim et al., 2007 Ben Abdelkrim, N. B., El Fazaa, S. and El Ati, J. 2007. Time–motion analysis and physiological data of elite under-19-year-old basketball players during competition. British Journal of Sports Medicine, 41: 6975. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]). These observations must be taken into account by coaches and conditioning specialists working with female players.  相似文献   

11.
Abstract

In the present study, a measure to assess the motivational qualities of music in exercise was redesigned, extending previous research efforts (Karageorghis et al., 1999 Karageorghis, C. I., Terry, P. C. and Lane, A. M. 1999. Development and initial validation of an instrument to assess the motivational qualities of music in exercise and sport: The Brunel Music Rating Inventory. Journal of Sports Sciences, 17: 713724. [Taylor & Francis Online], [Web of Science ®] [Google Scholar]). The original measure, the Brunel Music Rating Inventory (BMRI), had shown limitations in its factor structure and its applicability to non-experts in music selection. Redesign of the BMRI used in-depth interviews with eight participants (mean age 31.9 years, s = 8.9 years) to establish the initial item pool, which was examined using a series of confirmatory factor analyses. A single-factor model provided a good fit across three musical selections with different motivational qualities (comparative fit index, CFI: 0.95–0.98; standardized root mean residual, SRMR: 0.03–0.05). The single-factor model also demonstrated acceptable fit across two independent samples and both sexes using one piece of music (CFI: 0.86–1.00; SRMR: 0.04–0.07). The BMRI was designed for experts in selecting music for exercise (e.g. dance aerobic instructors), whereas the BMRI-2 can be used both by exercise instructors and participants. The psychometric properties of the BMRI-2 are stronger than those of the BMRI and it is easier to use. The BMRI-2 provides a valid and internally consistent tool by which music can be selected to accompany a bout of exercise or a training session. Furthermore, the BMRI-2 enables researchers to standardize music in experimental protocols involving exercise-related tasks.  相似文献   

12.
The present study investigated the nomological validity of the Amotivation Inventory–Physical Education (Shen, Wingert, Li, Sun, & Rukavina, 2010b Shen, B., Wingert, R. K., Li, W., Sun, H. and Rukavina, P. B. 2010b. An amotivation model in physical education. Journal of Teaching in Physical Education, 29: 7284. [Web of Science ®] [Google Scholar]) scores by examining the associations of ability, effort, value, and task characteristics amotivation beliefs with self-determination theory variables. Data were collected from 401 fifth- and sixth-grade students, 416 middle-school students, and 401 high-school students. After providing support for the correlated four-factor structure, the hierarchical structure, internal consistency, and composite reliability of the Amotivation Inventory–Physical Education scores, large negative correlations emerged with perceived autonomy support by the PE teacher; needs for autonomy, competence, and relatedness; identified regulation; intrinsic motivation; and students' subjective vitality. Strong positive correlations were obtained with unidimensional amotivation and external regulation, and weak correlations were obtained with introjected regulation. Also, multidimensional amotivation beliefs partially mediated the relationship between the need for autonomy and subjective vitality. The results provided support for the nomological aspect of construct validity of the Amotivation Inventory–Physical Education scores.  相似文献   

13.
Abstract

This study documents the effect of players' dismissals on team performance in professional soccer. Our aim was to determine whether the punishment meted out for unacceptable player behaviour results in reduced team performance. The official web site of the German Soccer Association was used for coding data from games played in the first Bundesliga between the 1963 – 64 and 2003 – 04 (n = 41) seasons. A sample of 743 games where at least one red card was issued was used to test hypotheses derived from crisis theory (Bar-Eli & Tenenbaum, 1989a Bar-Eli, M. and Tenenbaum, G. 1989a. A theory of individual psychological crisis in competitive sport. Applied Psychology, 38: 107120. [Crossref], [Web of Science ®] [Google Scholar]). Players' dismissals weaken a sanctioned team in terms of the goals and final score following the punishment. The chances of a sanctioned team scoring or winning were substantially reduced following the sanction. Most cards were issued in the later stages of matches. The statistics pertaining to outcome results as a function of game standing, game location, and time phases – all strongly support the view that teams can be considered conceptually similar to individuals regarding the link between stress and performance. To further develop the concept of team and individual psychological performance crisis in competition, it is recommended that reversal theory (Apter, 1982 Apter, M. J. 1982. The experience of motivation: The theory of psychological reversals, London: Academic Press.  [Google Scholar]) and self-monitoring and distraction theories (Baumeister, 1984 Baumeister, R. F. and Steinhilber, A. 1984. Paradoxical effects of supportive audiences on performance under pressure: The home field disadvantage in sports championships. Journal of Personality and Social Psychology, 47: 8593. [Crossref], [Web of Science ®] [Google Scholar]) be included in the design of future investigations pertaining to choking under pressure.  相似文献   

14.
Abstract

Coping strategies are important for performance in sport and individual differences may contribute to the coping strategies adopted by athletes. In this study, we explored the main and interactive effects of the big five personality dimensions on sport-related coping and compared personality profiles of discrete groups of athletes. Altogether, 253 athletes (mean age 21.1 years, s = 3.7) completed the NEO-FFI (Costa & McCrae, 1992 Costa, P. T. and McCrae, R. R. 1992. Revised NEO personality inventory and NEO five-factor inventory: Professional manual, Odessa, FL: Psychological Assessment Resources.  [Google Scholar]), and the Coping Function Questionnaire for Sport (Kowalski & Crocker, 2001 Kowalski, K. C. and Crocker, P. R. E. 2001. Development and validation of the Coping Function Questionnaire for adolescents in sport. Journal of Sport and Exercise Psychology, 23: 136155. [Web of Science ®] [Google Scholar]). Results showed that extraverted athletes, who were also emotionally stable and open to new experiences (a three-way interaction effect), reported a greater use of problem-focused coping strategies. Conscientious athletes (main effect), and athletes displaying high levels of extraversion, openness, and agreeableness (a three-way interaction effect), reported a greater use of emotion-focused coping strategies, and athletes with low levels of openness, or high levels of neuroticism (main effects), reported a greater use of avoidance coping strategies. Different personality characteristics were observed between higher-level and lower-level athletes, between men and women athletes, and between individual and team sport athletes. These findings suggest that the five-factor model of personality can help distinguish various levels of athletic involvement and can help identify the coping strategies athletes are likely to adopt during participation.  相似文献   

15.
This study explores the longitudinal and subgroup measurement properties of a 10-item, physical activity decisional balance scale, previously published by Plotnikoff, Blanchard, Hotz, and Rhodes (2001 Plotnikoff, R. C., Blanchard, C., Hotz, S. B. and Rhodes, R. 2001. Validation of the decisional balance scales in the exercise domain from the Transtheoretical Model: A longitudinal test. Measurement in Physical Education and Exercise Science, 5: 191206. [Taylor & Francis Online] [Google Scholar]), within a diabetic sample of Canadian adults. Results indicated that a three-factor measurement model consistently improved model fit compared to the previously published two-factor model. Evidence of configural, metric, and scalar measurement invariance across time and among subgroups suggests that the 10-item decisional balance scale is appropriate for investigating associative relationships with other constructs and for comparing group means of the pros and cons subscales among a variety of diabetic population subgroups.  相似文献   

16.
The goal of the current study was to establish the factor validity of the Questionnaire Assessing School Physical Activity Environment (Robertson-Wilson, Lévesque, & Holden, 2007 Robertson-Wilson, J., Lévesque, L. and Holden, R. R. 2007. Development of a questionnaire assessing school physical activity environment. Measurement in Physical Education and Exercise Science, 11: 93107. [Taylor & Francis Online] [Google Scholar]) using confirmatory factor analysis procedures. Another goal was to establish internal reliability and test–retest reliability. The confirmatory factor analysis results of this study supported a slightly altered version of the Questionnaire Assessing School Physical Activity Environment's school physical activity environment subscale. Internal reliability was adequate, while test–retest reliability was questionable. In brief, the pattern of findings indicated that while the original Questionnaire Assessing School Physical Activity Environment is likely adequate for some research purposes, a slightly modified version (Questionnaire Assessing School Physical Activity Environment-R) was psychometrically stronger. However, given the distinct differences in samples used in the original validation study and the current study, more research on the psychometric properties of the Questionnaire Assessing School Physical Activity Environment is needed to determine if the current results and Robertson-Wilson et al.'s (2007 Robertson-Wilson, J., Lévesque, L. and Holden, R. R. 2007. Development of a questionnaire assessing school physical activity environment. Measurement in Physical Education and Exercise Science, 11: 93107. [Taylor & Francis Online] [Google Scholar]) results are sample specific.  相似文献   

17.
The Trichotomous Achievement Goal Scale was developed by Agbuga and Xiang (2008 Agbuga, B. and Xiang, P. 2008. Achievement goals and their relations to self-reported persistence/effort in secondary physical education: A trichotomous achievement goal framework. Journal of Teaching in Physical Education, 27: 179191. [Web of Science ®] [Google Scholar]) by including selected items from the scales of Duda and Nicholls (1992 Duda, J. L. and Nicholls, J. 1992. Dimensions of achievement motivation in schoolwork and sport. Journal of Educational Psychology, 84: 290299. [Crossref], [Web of Science ®] [Google Scholar]), Elliot (1999 Elliot, A. J. 1999. Approach and avoidance motivation and achievement goals. Educational Psychologist, 34: 169189. [Taylor & Francis Online], [Web of Science ®] [Google Scholar]), and Elliot and Church (1997 Elliot, A. J. and Church, M. A. 1997. A hierarchical model of approach and avoidance achievement motivation. Journal of Personality and Social Psychology, 72: 218232. [Crossref], [Web of Science ®] [Google Scholar]) and adapting them into Turkish. The scale consists of 18 items, and students rated each item on a 7-point Likert scale. To ascertain the validity and reliability of the Trichotomous Achievement Goal Scale, it was administered to 845 female and 861 male Turkish high school students attending three public schools in the 2008–2009 spring semester. Exploratory and confirmatory factor analyses were conducted, and Cronbach's alpha and Fornell and Larcker's (1981 Fornell, C. and Larcker, D. F. 1981. Evaluating structural equation models with unobservable variables and measurement error. Journal of Marketing Research, 18: 3950. [Crossref], [Web of Science ®] [Google Scholar]) criteria were tested on the items that measured the students' achievements, screening for the three distinct types of achievement goals proposed by the trichotomous framework. Based on the results of the study, the 16-item Trichotomous Achievement Goal Scale can be claimed as a valid a reliable scale.  相似文献   

18.
Abstract

Swain (1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) employed the mathematical model of Di Prampero et al. (1979 Di Prampero, P. E., Cortili, G., Mognoni, P. and Saibene, F. 1979. Equation of motion of a cyclist. Journal of Applied Physiology, 47: 201206. [PubMed], [Web of Science ®] [Google Scholar]) to predict that, for cycling time-trials, the optimal pacing strategy is to vary power in parallel with the changes experienced in gradient and wind speed. We used a more up-to-date mathematical model with validated coefficients (Martin et al., 1998 Martin, J. C., Milliken, D. L., Cobb, J. E., McFadden, K. L. and Coggan, A. R. 1998. Validation of a mathematical model for road cycling power. Journal of Applied Biomechanics, 14: 276291. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) to quantify the time savings that would result from such optimization of pacing strategy. A hypothetical cyclist (mass = 70 kg) and bicycle (mass = 10 kg) were studied under varying hypothetical wind velocities (?10 to 10 m · s?1), gradients (?10 to 10%), and pacing strategies. Mean rider power outputs of 164, 289, and 394 W were chosen to mirror baseline performances studied previously. The three race scenarios were: (i) a 10-km time-trial with alternating 1-km sections of 10% and ?10% gradient; (ii) a 40-km time-trial with alternating 5-km sections of 4.4 and ?4.4 m · s?1 wind (Swain, 1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]); and (iii) the 40-km time-trial delimited by Jeukendrup and Martin (2001 Jeukendrup, A. E. and Martin, J. 2001. Improving cycling performance: How should we spend our time and money?. Sports Medicine, 31: 559569. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]). Varying a mean power of 289 W by ± 10% during Swain's (1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) hilly and windy courses resulted in time savings of 126 and 51 s, respectively. Time savings for most race scenarios were greater than those suggested by Swain (1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]). For a mean power of 289 W over the “standard” 40-km time-trial, a time saving of 26 s was observed with a power variability of 10%. The largest time savings were found for the hypothetical riders with the lowest mean power output who could vary power to the greatest extent. Our findings confirm that time savings are possible in cycling time-trials if the rider varies power in parallel with hill gradient and wind direction. With a more recent mathematical model, we found slightly greater time savings than those reported by Swain (1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]). These time savings compared favourably with the predicted benefits of interventions such as altitude training or ingestion of carbohydrate-electrolyte drinks. Nevertheless, the extent to which such power output variations can be tolerated by a cyclist during a time-trial is still unclear.  相似文献   

19.
Salivary cortisol is often used as an index of physiological and psychological stress in exercise science and psychoneuroendocrine research. A primary concern when designing research studies examining cortisol stems from the high cost of analysis. Planned missing data designs involve intentionally omitting a random subset of observations from data collection, reducing both the cost of data collection and participant burden. These designs have the potential to result in more efficient, cost-effective analyses with minimal power loss. Using salivary cortisol data from a previous study (Hogue, Fry, Fry, & Pressman, 2013 Hogue, C. M., Fry, M. D., Fry, A. C. and Pressman, S. D. 2013. The influence of a motivational climate intervention on participants’ salivary cortisol and psychological responses. Journal of Sport & Exercise Psychology, 35: 8597. [PubMed], [Web of Science ®] [Google Scholar]), this article examines statistical power and estimated costs of six different planned missing data designs using growth curve modeling. Results indicate that using a planned missing data design would have provided the same results at a lower cost relative to the traditional, complete data analysis of salivary cortisol.  相似文献   

20.
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