Abstract：
:Propulsive forces are important determinants of swimming performance. The aim of this study was to quantify the measurement error (uncertainty) in propulsive forces calculated from kinematic data. Ten operators digitized underwater video recordings of a breaststroke swimmer's right arm action. Four landmarks on the hand were digitized at 50 Hz and their three-dimensional coordinates obtained using a DLT algorithm. Two angles (alpha and psi) defining the orientation of the hand relative to the fluid flow were calculated following the procedures of Schleihauf et al. (1983). The hydrodynamic force acting on the hand (FR) was calculated using the force coefficients of Schleihauf (1979). Errors in single measurements of hand speed, alpha and psi were estimated for each video field analysed. Errors in alpha and psi led to average errors in the lift and drag coefficients of 27 and 20% respectively, which, when combined with an average hand speed error of 6%, produced an average error in FR of 26%. Each of these errors was reduced by a factor of square root 10 when the mean of 10 measurements was used to calculate FR. Researchers should report both the estimated errors in their hydrodynamic data and the procedures used to reduce them.
journal_name
J Sports Scijournal_title
Journal of sports sciencesauthors
Payton CJ,Bartlett RMdoi
10.1080/02640419508732261subject
Has Abstractpub_date
1995-12-01 00:00:00pages
447-54issue
6eissn
0264-0414issn
1466-447Xjournal_volume
13pub_type
杂志文章abstract：:The aim of this study was to compare ankle and knee joint moments observed when playing on sport surfaces that slide slightly relative to the ground with the moments observed when playing on conventional sport surfaces. Three-dimensional resultant internal joint moments and kinematic characteristics of the lower extre...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640410802669161
更新日期：2009-03-01 00:00:00
abstract：:Despite low mineral intakes in several groups of female 'ball-game' players, investigations of blood profiles and physical performance do not indicate any evident physiological benefits of micronutrient supplementation. Nevertheless, measurements of iron status are warranted, particularly in female athletes. Iron ther...
journal_title：Journal of sports sciences
pub_type： 杂志文章,评审
doi：
更新日期：1994-07-01 00:00:00
abstract：:This study aims to assess fundamental movement skill (FMS) proficiency, physical self-confidence levels, and the relationship between these variables and gender differences among adolescents. Three hundred and ninety five adolescents aged 13.78 years (SD = ±1.2) from 20 schools were involved in this study. The Test of...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2016.1235280
更新日期：2017-09-01 00:00:00
abstract：:This study addressed the paucity of evidence of whether visual anticipation can be improved in emerging experts in striking sports. Twelve emerging expert batsmen from a state cricket squad were equally randomised into intervention and control groups. They were pre-and-post tested on a video temporal occlusion test of...
journal_title：Journal of sports sciences
pub_type： 杂志文章,随机对照试验
doi：10.1080/02640414.2019.1621510
更新日期：2019-09-01 00:00:00
abstract：:Previous research on unstable footwear has suggested that it may induce mechanical noise during walking. The purpose of this study was to explore whether unstable footwear could be considered as a noise-based training gear to exercise body center of mass (CoM) motion during walking. Ground reaction forces were collect...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2018.1474726
更新日期：2018-12-01 00:00:00
abstract：:Twenty specialist marathon runners and 23 specialist ultra-marathon runners underwent maximal exercise testing to determine the relative value of maximum oxygen consumption (VO2max), peak treadmill running velocity, running velocity at the lactate turnpoint, VO2 at 16 km h-1, % VO2max at 16 km h-1, and running time in...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640419008732129
更新日期：1990-04-01 00:00:00
abstract：:This study characterises the relationship between gait variability and speed in runners using data from trunk accelerations in each axis. Twelve participants of varying fitness ran on the treadmill with three sessions of six randomly ordered self-selected speeds. A VO2max test was conducted on the fourth session. Runn...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2016.1262053
更新日期：2017-11-01 00:00:00
abstract：:This study aimed to explore how social media is being used by sports nutritionists as part of service provision, as well as practitioners' experiences and opinions of its use in practice. An exploratory sequential mixed methods approach was used during this research. Forty-four sports nutritionists completed an online...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2019.1642052
更新日期：2019-11-01 00:00:00
abstract：:In this study, we found that the optimum take-off angle for a long jumper may be predicted by combining the equation for the range of a projectile in free flight with the measured relations between take-off speed, take-off height and take-off angle for the athlete. The prediction method was evaluated using video measu...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640410400022011
更新日期：2005-07-01 00:00:00
abstract：:For the first time we aimed to: (1) assess fat-free mass (FFM) and RMR in youth soccer players, (2) compare measured RMR to estimated RMR using previously published prediction equations, and (3) develop a novel population-specific prediction equation. In a cross-sectional design, 99 males from a Premier League academy...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2020.1717286
更新日期：2020-01-01 00:00:00
abstract：:Present study examined the effects of conjugated linoleic acid (CLA) supplementation on glycogen resynthesis in exercised human skeletal muscle. Twelve male participants completed a cross-over trial with CLA (3.8 g/day for 8 week) or placebo supplements by separation of 8 weeks. CLA is a mixture of trans-10 cis-12 and...
journal_title：Journal of sports sciences
pub_type： 临床试验,杂志文章
doi：10.1080/02640414.2014.970219
更新日期：2015-01-01 00:00:00
abstract：:In this study, we examined (1) the relationship between self-talk and affect and (2) the nature of motivating self-talk. Ninety high-school athletes completed the Affect Grid and the Self-Talk Grid before practice and competition. Significant positive second-order partial correlations of low to moderate strength offer...
journal_title：Journal of sports sciences
pub_type： 临床试验,杂志文章
doi：10.1080/026404101750238926
更新日期：2001-07-01 00:00:00
abstract：:The aim of this study was to examine the occurrence of the sticking region by examining how three different grip widths affect the sticking region in powerlifters' bench press performance. It was hypothesised that the sticking region would occur at the same joint angle of the elbow and shoulder independent of grip wid...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2015.1046395
更新日期：2016-01-01 00:00:00
abstract：:The purpose of this study was to establish normative data for regional sweat sodium concentration ([Na+]) and whole-body sweating rate in athletes. Data from 506 athletes (367 adults, 139 youth; 404 male, 102 female) were compiled from observational athlete testing for a retrospective analysis. The participants were s...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2015.1055291
更新日期：2016-01-01 00:00:00
abstract：:Situational factors as well as individual differences are assumed to play an important role in perceptions of stress. One factor that may affect an elite athlete's perception of stress may be his or her perceived motivational climate. To examine the relative importance of dispositional and situational factors on the p...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/026404100365090
更新日期：2000-03-01 00:00:00
abstract：:The purpose of this study was to examine the accuracy of methods to estimate ball spin rate and spin axis direction using multi-camera tracking technology. The method implemented by Hawk-Eye and a theoretical ball trajectory model were assessed for their accuracy against high speed-vision. A theoretical ball trajector...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2019.1697189
更新日期：2020-02-01 00:00:00
abstract：:The aim of this study was to assess the effects of nicotinamide adenine dinucleotide hydride (NADH) on maximal oxygen uptake (VO2max), maximal anaerobic running time, and mental performance. Eight men were exposed to a supplement treatment (30 mg NADH as ENACHI tablets per day) and to a placebo treatment, each of 4 we...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640410701474200
更新日期：2008-02-01 00:00:00
abstract：:In two retroactive interference experiments, we assessed the effect of mentally imagined movement speed on subsequent motor performance. All participants performed a sequential motor action at three speeds during a baseline test and a retention test. During the retention interval of Experiment 1, the participants (n =...
journal_title：Journal of sports sciences
pub_type： 临床试验,杂志文章,随机对照试验
doi：10.1080/02640410050082305
更新日期：2000-08-01 00:00:00
abstract：:We examined the influence of caffeine supplementation on cognitive performance and perceptual responses in female team-game players taking low-dose monophasic oral contraceptives of the same hormonal composition. Ten females (24 ± 4 years; 59.7 ± 3.5 kg body mass; 2-6 training sessions per week) took part in a randomi...
journal_title：Journal of sports sciences
pub_type： 杂志文章,随机对照试验
doi：10.1080/02640414.2015.1052746
更新日期：2016-01-01 00:00:00
abstract：:Coaches are central to talent development in youth soccer and what they say and do impacts on players' achievements and well-being. Researchers have systematically observed coach behaviour and practice activities within this setting (i.e. 'what coaches do'). We review this research in light of contemporary discussion ...
journal_title：Journal of sports sciences
pub_type： 杂志文章,评审
doi：10.1080/02640414.2012.721930
更新日期：2012-01-01 00:00:00
abstract：:The purpose of this investigation was to analyze the validity and reliability of an iPhone app (named: Dorsiflex) for the measurement of weight-bearing ankle dorsiflexion. To do this, twelve healthy participants (age=28.6±2.3 years) performed a weight-bearing lunge test with each leg in five separate occasions, while ...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2018.1494908
更新日期：2019-02-01 00:00:00
abstract：:The aim of this study was to compare thoracic spine alignment with two- and three-dimensional calculations of shoulder alignment (defined as a line joining the acromion processes of the right and left scapula) when all measures were projected onto the transverse plane. A six-camera Vicon system was used to reconstruct...
journal_title：Journal of sports sciences
pub_type： 杂志文章
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更新日期：2002-06-01 00:00:00
abstract：:Laboratory-based studies indicate mild dehydration adversely affects mood. Although ultra-endurance events often result in mild to moderate dehydration, little research has evaluated whether the relationship between hydration status and mood state also exists in these arduous events. Therefore, the purpose of this stu...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2015.1021275
更新日期：2015-01-01 00:00:00
abstract：:Although it has been generally assumed that the risk of decompression sickness is virtually zero during a single breath-hold dive in humans, repeated dives may result in a cumulative increase in the tissue and blood nitrogen tension. Many species of marine mammals perform extensive foraging bouts with deep and long di...
journal_title：Journal of sports sciences
pub_type： 杂志文章,评审
doi：10.1080/02640410903121351
更新日期：2009-12-01 00:00:00
abstract：:Previous research has highlighted the positive effect that different warm-up protocols have on golf performance (e.g. Sorbie et al., 2016; Tilley & Macfarlane, 2012) with the design of warm-ups and programmes targeting and improving golf performance through the activation and development of specific muscle groups. Thi...
journal_title：Journal of sports sciences
pub_type： 杂志文章,随机对照试验
doi：10.1080/02640414.2018.1522699
更新日期：2019-03-01 00:00:00
abstract：:The aim of this study was to observe changes in the kinematics and muscle activities when barefoot running was initially adopted by six habitually shod, recreational rearfoot striking runners. Participants ran on a treadmill shod for 5 min, completed 3 × 10-min intervals of barefoot running and then completed a final ...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2015.1034756
更新日期：2016-01-01 00:00:00
abstract：:Since junior performances have little predictive value for future success, other solutions are sought to assess a young player's potential. The objectives of this systematic review are (1) to provide an overview of instruments measuring personal talent determinants of young players in racquet sports, and (2) to evalua...
journal_title：Journal of sports sciences
pub_type： 杂志文章,评审
doi：10.1080/02640414.2015.1061201
更新日期：2016-01-01 00:00:00
abstract：:Fundamental movement skills (FMS) have been assessed in children in order to investigate the issues of the low proportion of children who meet physical activity (PA) guidelines and rising levels of obesity. The aim of this research was to identify whether previous or current FMS level is a better predictor of PA level...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2014.918644
更新日期：2014-01-01 00:00:00
abstract：:Longitudinal research provides valuable information about change and progress towards elite performance. Unfortunately, there is a lack of longitudinal research in handball. In this study, 94 youth handball players (oldest group: n = 41; age 15-17 and youngest group: n = 53; age 13-15) were followed over a three-year ...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/02640414.2012.733819
更新日期：2013-01-01 00:00:00
abstract：:In this study, we examined the relationships between body sway, aim point fluctuation and performance in rifle shooting on an inter- and intra-individual basis. Six elite shooters performed 20 shots under competition conditions. For each shot, body sway parameters and four aim point fluctuation parameters were quantif...
journal_title：Journal of sports sciences
pub_type： 杂志文章
doi：10.1080/0264041031000101881
更新日期：2003-07-01 00:00:00
