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1.
Abstract

In this study, we examined the effect of two creatine monohydrate supplementation regimes on 24-h urinary creatine and methylamine excretion. Nine male participants completed two trials, separated by 6 weeks. Participants ingested 4 × 5 g · day?1 creatine monohydrate for 5 days in one trial and 20 × 1 g · day?1 for 5 days in the other. We collected 24-h urine samples on 2 baseline days (days 1–2), during 5 days of supplementation (days 3–7), and for 2 days post-supplementation (days 8–9). Urine was assayed for creatine using high-performance liquid chromatography and methylamine using gas chromatography. Less creatine was excreted following the 20 × 1 g · day?1 regime (49.25 ± 10.53 g) than the 4 × 5 g · day?1 regime (62.32 ± 9.36 g) (mean ± s; P < 0.05). Mean total excretion of methylamine (n = 6) over days 3–7 was 8.61 ± 7.58 mg and 24.81 ± 25.76 mg on the 20 × 1 g · day?1 and 4 × 5 g · day?1 regimes, respectively (P < 0.05). The lower excretion of creatine using 20 × 1 g · day?1 doses suggests a greater retention in the body and most probably in the muscle. Lower and more frequent doses of creatine monohydrate appear to further attenuate formation of methylamine.  相似文献   

2.
We assessed the relationship between young children's movement skills and their physical activity in early adolescence. Balance, agility, eye-hand coordination, and skinfold thicknesses in 207 Mexican American and Anglo American children (104 boys, 103 girls) were measured at ages 4, 5, and 6 years. Habitual physical activity was assessed at the age of 12 years by two interviewer-administered 7-day recalls. Ethnic differences in movement skills were not found. Young girls were better at jumping and balancing, and young boys were better at catching. Tracking of skills was low, and children's early childhood skills were not related to their physical activity 6 years later. Further studies involving additional movement skills and other populations are recommended to determine if enhanced movement skills in children promote subsequent physical activity.  相似文献   

3.
ABSTRACT

This study aimed to investigate the effects of different training modalities on the soluble Klotho (S-Klotho) plasma levels in sedentary middle-aged adults. A total of 74 middle-aged adults (53.4 ± 5.0 years old; 52.7% women) were enrolled in the FIT-AGEING study. We conducted a 12-week randomised controlled trial. The participants were randomly assigned to 4 different groups: (i) a control group (no exercise), (ii) a physical activity recommendation from the World Health Organization group (PAR), (iii) a high intensity interval training group (HIIT), and (iv) a high intensity interval training group adding whole-body electromyostimulation training group (HIIT-EMS). S-Klotho plasma levels, anthropometric measurements, and body composition variables were measured before and after the intervention programme. All exercise training modalities induced an increase in the S-Klotho plasma levels (all P ≤ 0.019) without statistical differences between them (all P ≥ 0.696). We found a positive association between changes in lean mass index and changes in the S-Klotho plasma levels, whereas a negative association was reported between changes in fat mass outcomes and changes in the S-Klotho plasma levels after our intervention study. In conclusion, our results suggest that the link between exercise training and the increase in S-Klotho plasma levels could be mediated by a decrease of fat mass and an increase of lean mass.  相似文献   

4.
Health literacy represents an increasingly important subject in health sciences. This article initially illustrates a domain-specific model of physical activity-related health competence. Movement competence, control competence, and PA-specific self-regulation competence are described as sub-competencies.  相似文献   

5.
In recent years, Pop Warner, the world’s largest youth football organization, has seen its numbers decline. This decline is due to concerns about new research establishing a link between football and chronic traumatic encephalopathy, a debilitating neurodegenerative disease. Hundreds of thousands of parents are now struggling with a difficult ethical issue: should kids play football? Since parents have an obligation to help children develop the capacities required for autonomous choice, the risks posed by football establish a strong presumption against allowing kids to play the game. I consider whether this presumption can be defeated by the arguments for allowing kids to play dangerous sports offered by John Russell in his papers ’The Value of Dangerous Sport’ and ‘Children and Dangerous Sport and Recreation’. While Russell does not argue that kids should be permitted to play football, and agrees that some sports may be too risky for children, he argues that kids should often be allowed to participate in extraordinarily risky sports. I contend that the reasons given in support of this position fail to defeat the presumption against allowing kids to play football. Thus, in the absence of further argument, or radical changes to the game, children should not play football.  相似文献   

6.
Abstract

The aim of this study was to quantify the movement patterns of various playing positions during professional rugby union match-play, such that the relative importance of aerobic and anaerobic energy pathways to performance could be estimated. Video analysis was conducted of individual players (n=29) from the Otago Highlanders during six “Super 12” representative fixtures. Each movement was coded as one of six speeds of locomotion (standing still, walking, jogging, cruising, sprinting, and utility), three states of non-running intensive exertion (rucking/mauling, tackling, and scrummaging), and three discrete activities (kicking, jumping, passing). The results indicated significant demands on all energy systems in all playing positions, yet implied a greater reliance on anaerobic glycolytic metabolism in forwards, due primarily to their regular involvement in non-running intense activities such as rucking, mauling, scrummaging, and tackling. Positional group comparisons indicated that while the greatest differences existed between forwards and backs, each positional group had its own unique demands. Front row forwards were mostly involved in activities involving gaining/retaining possession, back row forwards tended to play more of a pseudo back-line role, performing less rucking/mauling than front row forwards, yet being more involved in aspects of broken play such as sprinting and tackling. While outside backs tended to specialize in the running aspects of play, inside backs tended to show greater involvement in confrontational aspects of play such as rucking/mauling and tackling. These results suggest that rugby training and fitness testing should be tailored specifically to positional groups rather than simply differentiating between forwards and backs.  相似文献   

7.
Abstract

The objective of this study was to determine whether sprint performance is related to the mechanical (elongation – force relationship of the tendon and aponeurosis, muscle strength) and morphological (fascicle length, pennation angle, muscle thickness) properties of the quadriceps femoris and triceps surae muscle – tendon units. Two groups of sprinters (slow, n = 11; fast, n = 17) performed maximal isometric knee extension and plantar flexion contractions on a dynamometer at 11 different muscle – tendon unit lengths. Elongation of the tendon and aponeurosis of the gastrocnemius medialis and the vastus lateralis was measured using ultrasonography. We observed no significant differences in maximal joint moments at the ankle and knee joints or morphological properties of the gastrocnemius medialis and vastus lateralis between groups (P > 0.05). The fast group exhibited greater elongation of the vastus lateralis tendon and aponeurosis at a given tendon force, and greater maximal elongation of the vastus lateralis tendon and aponeurosis during maximum voluntary contraction (P < 0.05). Furthermore, maximal elongation of the vastus lateralis tendon and aponeurosis showed a significant correlation with 100-m sprint times (r = ?0.567, P = 0.003). For the elongation – force relationship at the gastrocnemius medialis tendon and aponeurosis, the two groups recorded similar values. It is suggested that the greater elongation of the vastus lateralis tendon and aponeurosis of the fast group benefits energy storage and return as well as the shortening velocity of the muscle – tendon unit.  相似文献   

8.
From February 17th to 22nd, annual World Magic Seminar was held in Las Vegas, U.S.A. There were 850 attendees from all over the world. Representatives from China Acrobats Association took part in the events in order to make promotion for the World Championships of Magic 2009 in Beijing. We set up a promotion booth,  相似文献   

9.
Abstract

Our aim was to present a mathematical model of rowing and sculling that allowed for a comparison of oar blade designs. The relative movement between the oar blades and water during the drive phase of the stroke was modelled, and the lift and drag forces generated by this complex interaction were determined. The model was driven by the oar shaft angular velocity about the oarlock in the horizontal plane, and was shown to be valid against measured on-water mean steady-state shell velocity for both a heavyweight men's eight and a lightweight men's single scull. Measured lift and drag force coefficients previously presented by the authors were used as inputs to the model, whichs allowed for the influence of oar blade design on rowing performance to be determined. The commonly used Big Blade, which is curved, and it's flat equivalent were compared, and blade curvature was shown to generate a 1.14% improvement in mean boat velocity, or a 17.1-m lead over 1500 m. With races being won and lost by much smaller margins than this, blade curvature would appear to play a significant role in propulsion.  相似文献   

10.
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11.
TEAM3D热情、奉献与纪律：Team3D的美国梦Desire Dedication Discipline:The American Dream of Team3D Team 3D的故事,是一个美国梦的故事。至少Team 3D的历程,符合无数青年人的梦想。在一种具有包容性的文化下成长起来的年轻人,多元化的生活方式的理念已经深入人心,在这样的背景下,成功的外延被无限的放大。从Volcanno登上华盛顿邮报开始,标志着Team3D代表的独立自主的思想被西方主流社会所认知。  相似文献   

12.
Abstract

This study examined the impact of high and low proficiency level, transfer distality, and gender on the contextual interference effect with an open skill. Subjects were separated into two levels of proficiency based on performance on a pretest similar to the experimental task. Analysis of error scores during acquisition indicated that the partitioning of subjects according to ability level had been successful. Transfer distality was varied by presenting subjects with two tasks varying in similarity to the acquisition task. Analysis of absolute constant, constant, variable, and total error scores in transfer strongly suggested that subjects' consistency rather than response bias was affected by the experimental variables. The findings suggested that, for the task used in this study, proficiency level does not account for gender differences in the contextual interference effect, as the effect was only reliably found for females. For coincident timing skills, it appears that there may be two distinct conclusions drawn from the results of this study: contextual interference only benefits female subjects' consistency and the effect of contextual interference increases with the distality of transfer, regardless of the subjects' proficiency level.  相似文献   

13.
The purpose of this study was to compare home advantage at the top two levels of the domestic leagues of a wide selection of countries worldwide. Limited previous work has been inconclusive with home advantage at level 2 appearing at least as high as at level 1. Home advantage was quantified for the most recent seven seasons of the top two levels for 47 countries worldwide and included 168,341 matches. A paired t?test was used to assess the difference between levels for each country. Home advantage was significantly more likely to be higher at level 2 than at level 1. The difference was especially apparent in Bosnia–Herzegovina, Serbia and Iran (all p?<?0.001). Kazakhstan was the only country with a significantly higher advantage at level 1. Possible factors that might be contributing to this finding include players and referees at level 1 being better trained to avoid being influenced by crowd support. Level 2 players may be more intimidated by performing away from home, less well equipped to cope with unfamiliar surroundings and routines, and will also have travelled in less comfort.  相似文献   

14.
The aim of this paper is to describe and explain the changes in the gender balance of jockeyship in Swedish horse racing in the period 1890–2000. The change in gender coding, and its causes, are both complex. Two distinctive periods of change are argued to have been crucial, the 1940s and 1970s. In the first period women were given permission to ride in amateur races; in the second period they were allowed to become professionals. It is suggested here that the changes in the gender balance are explained by male support, the intersection of gender and social class and gender coding.  相似文献   

15.
Abstract

The purpose of this study was to evaluate the effects of a realistic, feasible, and commonly used fitness training programme on cardiac autonomic control in 14 sedentary men aged 62.0 ± 6.1 years (mean ± s). All participants performed a one-year fitness training programme in which training intensity and frequency were specifically chosen to be compliant for the majority of the participants (2 – 3 sessions per week at moderate intensity). At the same time, a reference group consisting of 15 sedentary age-matched men (age 64.2 ± 6.5 years) did not change their habitual physical activity. Measurements were performed before and after the training intervention. Cardiac autonomic control was inferred from resting values (supine and standing) of heart rate variability (HRV) computed in the frequency domain over 10-min intervals. Endurance capacity was evaluated during a maximal incremental bicycle ergometer test. In spite of an increase in peak oxygen consumption ([Vdot]O2peak) by 6.4% after training, heart rate in the training group remained unchanged at rest and at the same metabolic demand. No changes in resting parameters of HRV were shown for either groups or positions. Results from this study provide no evidence of a clinically meaningful increase in the vagal modulation to the sinus node at rest after one year of low-volume and moderate-intensity fitness training in men aged 55 – 75 years.  相似文献   

16.
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17.
The following research approximated how the central nervous system of Paralympic wheelchair athletes resolve kinematic redundancies during upper-limb movements. A multibody biomechanical model of a tetraplegic Paralympic athlete was developed using subject-specific body segment parameters. The angular joint kinematics throughout a specified Paralympic sport movement (i.e., wheelchair curling) were experimentally measured using inertial measurement units. The motor control system of the Paralympian was mathematically modelled and simulated using forward dynamics optimization. The predicted kinematics from different optimization objective functions (i.e., minimizing resultant joint moments, mechanical joint power, and angular joint velocities and accelerations) were compared with those experimentally measured throughout the wheelchair curling movement. Of the optimization objective functions under consideration, minimizing angular joint accelerations produced the most accurate predictions of the kinematic trajectories (i.e., characterized with the lowest overall root mean square deviations) and the shortest optimization computation time. The implications of these control findings are discussed with regards to optimal wheelchair design through predictive dynamic simulations.  相似文献   

18.
This paper compares French- and English-language Canadian television coverage of Australian Aboriginal athlete Cathy Freeman during the 2000 Olympics using a narrative framework. The specific focus of the analysis is the representation of Freeman's political identity as an agent and symbol of Aboriginal reconciliation – the struggle for apology, reparatio, and social justice in the light of the history and legacy of colonial oppression and exclusion. Freeman has used her sporting success to signify visibly and with some controversy her identification with political Aboriginality and reconciliation, and she went into the 2000 games bearing an unusual weight of expectation, intensified by being chosen to light the Olympic cauldron, that a victory in the 400 metres would mark symbolically reconciliation between Aboriginal and non-Aboriginal Australians. The analysis generally conforms the hypothesis that the normative dimension of these expectations would be accentuated more in the French- than English-language coverage, and this resulted in a more consistently affirmative portrayal of Freeman and her performance. The English-language coverage emphasized the ambivalent nature of her role. The corollary of this was that the English-language coverage paid greater attention to the substance of Aboriginal grievances and struggle. Nonetheless, neither network saw Freeman's identity in openly critical terms: in Freeman's Olympic narrative sport and politics were allowed to mix in a relatively unproblematic way.  相似文献   

19.
Modern Japan has considered global sport an appropriate forum for not only defining the national cultural identity of Japan but also for conducting its international diplomacy. The recent phenomenon of Japanese baseball athletes ‘defecting’ from Japanese leagues to play for the American baseball leagues has often been described in political terms. This paper argues that the current trend of analysing Japanese nationals playing baseball in America in political terms can be historically contextualized by reviewing the bids by Japanese cities for the 1940, 1964, 1998 and 2016 Olympic Games.  相似文献   

20.
This article examines theories and practices of moral and physical education among the Scottish missionaries in the Malawi region of south-central Africa during late nineteenth and early twentieth centuries. Within the wider history of British imperial education and the English public school games ethic, the Scottish missionaries of the Livingstonia and Blantyre missions offer an interesting and important counterpoint to their middle-class English counterparts. Although the Scots had their own distinct educational traditions which shaped their pedagogical programmes in Africa, they were not unaffected by the games ethic. Drill and team games gradually became an important part of missionary education in Blantyre and Livingstonia, with the holistic aim of developing the body, mind and moral character of the mission pupils. In Malawi, the games ethic, first introduced by middle-class Edinburgh missionaries, developed alongside an ‘industrial ethic’, and a distinctly ‘Scottish blend’ of missionary education that combined Scottish industrial and English non-industrial traditions emerged.  相似文献   

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