Bilateral arm power imbalance in swim bench exercise to exhaustion     

Potts AD  Charlton JE  Smith HM 《Journal of sports sciences》2002,20(12):975-979

We examined the supposition that swimmers may exhibit an imbalance in bilateral arm power output during simulated swimming exercise. Ten competitive front crawl swimmers (5 males, 5 females; age 20.5+/-2.3 years; height 1.74+/-0.09 m; body mass 72.0+/-16.7 kg; 400 m freestyle swim time 278+/-20.5 s; mean +/- s) performed four incremental (10 W x min(-1)) swim ramp tests on a computer-interfaced biokinetic swim bench ergometer. External power output from each arm was measured continuously to exhaustion. The results showed that, throughout the course of the simulated swim, external power output clearly favoured the left arm (F1,9 = 12.5, P= 0.006). This was especially evident in the final 30 s to exhaustion, when 54.0+/-3.87% of external power output was derived from the left arm versus 46.0+/-3.87% from the right arm. The disparity in external power output was further highlighted when the participants were grouped into unilateral and bilateral breathers. Unilateral breathers (n = 5) produced 57.1+/-2.62% of external power output from the left armversus 42.9+/-2.62% from the right arm (P= 0.001). Bilateral breathers (n = 5) exhibited a more balanced external power output of 51.0+/-1.82% from the left arm and 49.0+/-1.82% from the right arm (P = 0.177). Evidence of power imbalance in the simulated swimming stroke may have important implications for optimizing swim performance. The observed power imbalance may be reduced when a bilateral breathing technique is adopted.  相似文献   

Measurement of total energy expenditure by the doubly labelled water method in professional soccer players     

Ebine N  Rafamantanantsoa HH  Nayuki Y  Yamanaka K  Tashima K  Ono T  Saitoh S  Jones PJ 《Journal of sports sciences》2002,20(5):391-397

To determine the daily energy requirements of professional soccer players during a competitive season, we measured total energy expenditure in seven players (age 22.1+/-1.9 years, height 1.75+/-0.05 m, mass 69.8+/-4.7 kg; mean +/- s) using the doubly labelled water method. Energy intake was simultaneously estimated from 7 day self-report dietary records. Mean total energy expenditure and energy intake were 14.8+/-1.7 MJ x day(-1) (3532+/-408 kcal x day(-1)) and 13.0+/-2.4 MJ x day(-1) (3113+/-581 kcal x day(-1)), respectively. Although there was a significant difference between total energy expenditure and energy intake (P < 0.01), there was a strong relationship between the two (r= 0.893, P< 0.01). Basal metabolic rate and recommended energy allowance calculated from the Recommended Dietary Allowances for the Japanese were 7.0+/-0.3 MJ x day(-1) (1683+/-81 kcal x day(-1)) and 15.6+/-0.8 MJ x day(-1) (3739+/-180 kcal x day(-1)), respectively. A physical activity level (total energy expenditure/ basal metabolic rate) of 2.11+/-0.30 indicated that, during the competitive season, professional soccer players undertake much routine physical activity, similar to that of competitive athletes during moderate training. Energy intake estimated using dietary records was under-reported, suggesting that its calculation from these data does not predict energy expenditure in soccer players.  相似文献   

Effect of verbal instructions and image size on visual search strategies in basketball free throw shooting     

Al-Abood SA  Bennett SJ  Hernandez FM  Ashford D  Davids K 《Journal of sports sciences》2002,20(3):271-278

We assessed the effects on basketball free throw performance of two types of verbal directions with an external attentional focus. Novices (n = 16) were pre-tested on free throw performance and assigned to two groups of similar ability (n = 8 in each). Both groups received verbal instructions with an external focus on either movement dynamics (movement form) or movement effects (e.g. ball trajectory relative to basket). The participants also observed a skilled model performing the task on either a small or large screen monitor, to ascertain the effects of visual presentation mode on task performance. After observation of six videotaped trials, all participants were given a post-test. Visual search patterns were monitored during observation and cross-referenced with performance on the pre- and post-test. Group effects were noted for verbal instructions and image size on visual search strategies and free throw performance. The 'movement effects' group saw a significant improvement in outcome scores between the pre-test and post-test. These results supported evidence that this group spent more viewing time on information outside the body than the 'movement dynamics' group. Image size affected both groups equally with more fixations of shorter duration when viewing the small screen. The results support the benefits of instructions when observing a model with an external focus on movement effects, not dynamics.  相似文献   

Individual pathways in the development of forceful throwing     

Langendorfer SJ  Roberton MA 《Research quarterly for exercise and sport》2002,73(3):245-256

Halverson, Roberton, and Langendorfer (1982) reported the development of children ages 6-13 years filmed longitudinally performing the forceful overarm throw. These authors described the children's progress through developmental sequences for trunk, humerus, and forearm actions; however, they did not study developmental relationships ("profiles") across these components. This paper reports how the profiles changed in the same children across trials within filming sessions and over time. The data revealed both common and individual developmental pathways. The frequencies of some pathways were not chance occurrences (p < or = .01), suggesting that within-person constraints eliminated certain movement relationships while encouraging others. The authors hypothesize that the kinematics of trunk rotation may serve as a control parameter for pattern change.  相似文献   

Visual search and biological motion perception in tennis   总被引：1，自引：0，他引：1  

Ward P  Williams AM  Bennett SJ 《Research quarterly for exercise and sport》2002,73(1):107-112

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Association of parent and peer support with adolescent physical activity     

Prochaska JJ  Rodgers MW  Sallis JF 《Research quarterly for exercise and sport》2002,73(2):206-210

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Cognitive interference during competition among volleyball players with different goal orientation profiles     

Hatzigeorgiadis A  Biddle SJ 《Journal of sports sciences》2002,20(9):707-715

In this study, we examined interfering thoughts during sport competition among university volleyball players as a function of dominant goal orientation and outcome. In particular, we investigated the performance worries and thoughts of escape experienced while performing in athletes with high task and low ego orientation and athletes with high ego and low task orientation. Goal orientations were assessed before the start of a volleyball tournament, whereas cognitive interference was assessed on three different occasions after games. The results revealed no consistent differences for performance worries. In contrast, in all analyses we found that athletes with high ego and low task orientations reported more thoughts of escape when losing than when winning, and more thoughts of escape than athletes with high task and low ego orientations when winning or losing. The results support in part the suggestion that a high ego orientation, when not accompanied by a high task orientation, can be linked to motivationally maladaptive cognitions.  相似文献   

Book reviews     

Anthony Watkinson  J.D. Lee  Anthony Watkinson  Kurt Paulus 《Learned Publishing》2002,15(4):307-312

Gaining Independence: A Manual for Planning the Launch of a Nonprofit Electronic Publishing Venture, version 1.0 by Howard Goldstein Published by SPARC, available online: http://www.arl.org/sparc/GI Indexers and Indexing in Fact and Fiction edited by Hazel K. Bell The British Library, London, 2001. Pp. 160. Paper, £16. ISBN 0-7123-4729-1 Preservation Management of Digital Materials: A Handbook by Maggie Jones and Neil Beagrie The British Library, Nov. 2001. Pp. 145. Spiral bound, £15.00. ISBN 0 7123 0886 5. Copies can be ordered from Turpin Distribution Services Ltd. Publishing Law, 2nd edn by Hugh Jones and Christopher Benson Routledge, 2002. Cased, £65.00, ISBN 0-415-26153-8; paper, £24.99, ISBN 0-415-26154-6 How to Survive Peer Review by Elizabeth Wager, Fiona Godlee and Tom Jefferson London: BMJ Books, 2002. Pp. v + 62. £12.95. ISBN 0-7279-1686-6  相似文献   

Josep Laporte Library Foundation: a model of knowledge management in the life and health sciences     

Jovell AJ 《Health information and libraries journal》2002,19(3):176-180

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The effect of ball carrying method on sprint speed in rugby union football players     

Grant SJ  Oommen G  McColl G  Taylor J  Watkins L  Friel N  Watt I  McLean D 《Journal of sports sciences》2003,21(12):1009-1015

Different methods of ball carrying can be used when a player runs with the ball in rugby union. We examined how three methods of ball carrying influenced sprinting speed: using both hands, under the left arm and under the right arm. These methods were compared with running without the ball. Our aim was to determine which method of ball carrying optimizes sprinting speed. Altogether, 48 rugby union players (age 21 +/- 2 years, height 1.83 +/- 0.1 m, body mass 85.3 +/- 12 kg, body fat 14 +/- 5%; mean +/- s) were recruited. The players performed twelve 30-m sprints in total (each player performed three trials under each of three methods of carrying the ball and sprinting without the ball). The design of the study was a form of Latin rectangle, balanced across the trial order for each of the methods and for pairwise combinations of the methods in blocks of four per trial. Each sprint consisted of a 10-m rolling start, followed by a 20-m timed section using electronic timing gates. Compared with sprinting 20 m without the ball (2.58 +/- 0.16 s), using both hands (2.62 +/- 0.16 s) led to a significantly slower time (P < 0.05). Sprinting 20 m with the ball under the left arm (2.61 +/- 0.15 s) or under the right arm (2.60 +/- 0.17 s) was significantly quicker than when using 'both hands' (P < 0.05), and both these methods were significantly slower than when running without the ball (P < 0.05). Accordingly, running with the ball in both hands led to the greatest decrement in sprinting performance, although carrying the ball under one arm also reduced the players' sprinting ability. Our results indicate that to gain a speed advantage players should carry the ball under one arm.  相似文献