Body mass changes and nutrient intake of dinghy sailors while racing

Dinghy sailing is a physically challenging sport with competitors on water for several hours. Regulations and space in the boat limit the amount of food and fluid competitors can carry. Consequently, it is possible that the hydration and nutritional status of dinghy sailors may be compromised while racing. Despite this, the food and fluid intake of sailors while racing are unknown. The aim of this study was to assess the dietary intake of a group of club sailors while racing and compare this with current sports nutrition guidelines. Thirty-five sailors (9 females, 26 males) were monitored during a club regatta. Body mass changes were measured before and after racing, as were food and fluid intake. Results showed that most participants were in negative fluid balance after racing (males: mean -2.1%[95% confidence limits -1.7 to -2.5%]; females: -0.9%[0 to -1.8%]), most likely due to low voluntary fluid intake (males: 1215 ml [734 to 1695 ml]; females: 792 ml [468 to 1117 m]). Carbohydrate intake (males: 59 g [21 to 97 g]; females: 30 g [0 to 61 g]) was below recommendations for normal sports activity. Results revealed that the nutritional practices of club sailors do not comply with current sports nutrition guidelines. However, the performance implications of a compromise in nutrient intake remain to be investigated. Practical advice on methods of overcoming space limitations for the carriage of adequate fluid and food is offered.     

Double poling kinematic changes during the course of a long-distance race: effect of performance level

ABSTRACT

We aimed to evaluate the changes in double poling (DP) kinematics due to a long-distance cross-country skiing race in athletes with different performance levels. A total of 100 cross-country skiers, belonging to 10 different performance groups, were filmed on flat terrain 7 and 55 km after the start line, during a 58-km classical race. Cycle velocity, frequency and length decreased from the best to the lower-ranked group, while duty cycle increased (all P <.001). Between track sections, cycle velocity and length decreased, duty cycles increased (all P <.001) while frequency was unaltered (P =.782). Group*section interactions resulted for cycle velocity (P =.005). Considering all the participants together, % change in cycle velocity between sections correlated with % change in length and duty cycle (all P <.001). Thus i) skiers in better groups showed longer and more frequent cycles as well as shorter duty cycles than skiers in slower groups; ii) throughout the race all the groups maintained the same cycle frequency while decreasing cycle velocity and length; iii) better groups showed a lower reduction in cycle velocity. Individually, a low reduction in cycle velocity during the race related to the capacity to maintain long cycles and short duty cycles.     

Reliability of power output during rowing changes with ergometer type and race distance

Coaches, sport scientists and researchers assess rowing performance on-water and on a variety of ergometers. Ergometers are frequently used because of the easier assessment environment. However, there is limited information on the ability of rowers to reproduce mean power or time-trial time when using different rowing ergometers (Concept II and RowPerfect) or completing tests over different distances (500 m versus 2000 m races). To test the efficacy of an intervention on a rower's ability to produce power, or to monitor that ability, it is essential to determine a reliable rowing performance test. The per cent standard error of measurement in performance (assessed by mean power and time-trial time) of fifteen national standard rowers was determined for five repeated 500 m and two repeated 2000 m races on a Concept II and RowPerfect ergometer. The per cent standard error of measurement (% SEM) in mean power between 5x500m races, regardless of gender, was 2.8% (95% confidence limits (CL)=2.3 to 3.4%) for the Concept II ergometer and 3.3% (95% CL=2.5 to 3.9%) for the RowPerfect ergometer (n = 15). Over 2000 m the per cent standard error of measurement in mean power was 1.3% (95% CL 0.9 to 2.9%) for the Concept II ergometer and 3.3% (95% CL 2.2 to 7.0%) for the RowPerfect ergometer The results highlight an increase in per cent standard error of the mean during performance races of less than 2000m on the Concept II ergometer, and performance races on the RowPerfect ergometer compared with the Concept II ergometer over 500 m and 2000 m. The most appropriate protocol for testing the influence of an intervention on the ability of a rower to produce power would be 2000 m races on a Concept II ergometer.     

Nutritional intake and body composition changes in a UCI World Tour cycling team during the Tour of Spain

Abstract

The aim of this study was to quantify the food intake of an International Cyclist Union (UCI) World Tour professional cyclist team and to analyse changes in body composition during the Tour of Spain. Nine male professional road cyclists (31.3?±?3.0 years) volunteered to participate in the study. Nutritional data were collected each day throughout the 3-week Tour by two trained investigators who weighed the food ingested by the cyclists. Mean nutritional intake of the cyclists was as follows: carbohydrate, 12.5?±?1.8?g/kg/day of body weight (BW) (65.0?±?5.9%); fat, 1.5?±?0.5 g/kg/day BW (17.9?±?5.6%); and protein, 3.3?±?0.3?g/kg/day BW (17.1?±?1.6%). Intake of all micronutrients, except for folate, vitamin D and potassium (which were 78.7%, 46% and 84% of Recommended Dietary Allowances (RDA), respectively), exceeded the RDA. Height, weight, skinfolds, circumferences and diameters were taken following the guidelines outlined by the International Society for the Advancement of Kinanthropometry. Body density, body fat percentage, muscle mass, total muscle mass and fat mass of the arms and thighs were calculated. Percentage body fat, fat mass and upper arm fat mass significantly decreased (p < .05) after the Tour independent of the equation method used in the calculations. Total muscle mass remained unchanged. Generally, this sample of cyclists consumed more protein and less fat than the recommended amount and had low weight, BMI and fat mass. It is suggested that sports nutritionists design personalised diets in order to maintain a correct proportion of nutrients as well as controlling possible anthropometrical changes that could affect performance.     

Body composition of female road and track endurance cyclists: Normative values and typical changes

The aims of this study were to describe normative values and seasonal variation of body composition in female cyclists comparing female road and track endurance cyclists, and to validate the use of anthropometry to monitor lean mass changes. Anthropometric profiles (seven site skinfolds) were measured over 16 years from 126 female cyclists. Lean mass index (LMI) was calculated as body weight?×?skinfolds^?x. The exponent (x) was calculated as the slope of the natural logarithm of body weight and skinfolds. Percentage changes in LMI were compared to lean mass changes measured using dual-energy X-ray absorptiometry (DXA) in a subset of 25 road cyclists. Compared to sub-elite and elite cyclists, world class cyclists were (mean [95% CI]) 1.18?kg [0.46, 1.90] and 0.60?kg [0.05, 1.15] lighter and had skinfolds that were 7.4?mm [3.8, 11.0] and 4.6?mm [1.8, 7.4] lower, respectively. Body weight (0.41?kg [0.04, 0.77]) and skinfolds (4.0?mm [2.1, 6.0]) were higher in the off-season compared to the early-season. World class female road cyclists had lower body weight (6.04?kg [2.73, 9.35]) and skinfolds (11.5?mm [1.1, 21.9]) than track endurance cyclists. LMI (mean exponent 0.15 [0.13, 0.18]) explained 87% of the variance in DXA lean mass. In conclusion, higher performing female cyclists were lighter and leaner than their less successful peers, road cyclists were lighter and leaner than track endurance cyclists, and weight and skinfolds were lowest early in the season. LMI appears to be a reasonably valid tool for monitoring lean mass changes.     

机体高功率输出与体脂关系的研究

通过对北京、安徽部分地区在校学生身体成分及无氧功率的群体测试，了解由于饮食、卫生、锻炼等生活习惯的不同而产生的身体成分的变化，无氧功率的差距，从而找出二者之间的关系、相互影响的程度以及高体脂学生的检出率，为贯彻国家体育锻炼标准、学校体育的开展、青少年的体质研究提供数据资料。     

Power and pacing calculations based on real-time locating data from a cross-country skiing sprint race

Pacing strategies in cross-country skiing have been investigated in several studies. However, none of the previous studies have been verified by collected skiing data giving the skiing velocities along a measured track. These can be used to calculate the propulsive power output. Collected real-time positioning data from a cross-country sprint skiing race were used to estimate the propulsive power by applying a power balance model. Analyses were made for the time-trial and the final for one female and one male skier. The average propulsive power over the whole race times were 311 and 296 W during the time trial and 400 and 386 W during the final, for the female and male skier, respectively. Compared to the average propulsive power over the whole race, the average active propulsive phases were calculated as 33 and 44% higher in the time trials and 36 and 37% higher in the finals for the female and male, respectively. The current study presents a novel approach to use real-time positioning data to estimate continuous propulsive power during cross-country sprint skiing, enabling in-depth analyses of power output and pacing strategies.     

我国农村居民消费结构的变迁对群众体育的影响

农村居民六大类消费结构的演变从不同角度作用于群众体育事业：1）食品衣着类从“温饱型”到“小康型”，为群众体育的发展提供了前提条件；2）居住类消费支出比重过高，一定程度上限制了群众体育在农村的普及；3）家庭设备及服务类消费变化缓慢，阻碍了体育消费水平；4）医疗保健类支出渐增，促进了农村居民新型价值观的形成和健身保健意识的增强；5）交通通讯的发展使农村居民养成良好体育习惯；6）文教娱乐用品及服务类消费反映出农村居民素质不高，造成体育发展滞后于城市。     

身体姿势和形体练习文献综述

在近十年文献资料的基础上 ,综述了身体姿势的测量方法 ,部分异常姿势的检出率、生理机制和形体练习的内容等已有的研究成果。为促进青少年拥有正确的身体姿势和优美的形体 ,作更进一步研究提供一定的依据和线索。     

浅析形体训练对高中女生身体形态、机能的影响

文章运用文献资料法、实验与数据统计法等研究方法,通过对高中女生体育教学中形体训练的实际教学效果的对比测试研究,来探讨形体训练对学生形态和机能的影响,从而证明了在高中女生体育教学中加强形体的素质训练势在必行。     

步态在提高青少年中长跑运动员成绩中的作用

为了总结训练经验，进一步吸取先进的运动技术，增强青少年中长跑运动员的竞技基础和实力，通过王军霞与宋某的步态分析，认为“高频跑”特征已成为一种技术发展趋势，较高的步频能力已成为优秀选手必备的能力之一，同时为中长跑技术训练提供一些切实可行的理论依据及对策。     

Foot strike patterns of recreational and sub-elite runners in a long-distance road race

Although the biomechanical properties of the various types of running foot strike (rearfoot, midfoot, and forefoot) have been studied extensively in the laboratory, only a few studies have attempted to quantify the frequency of running foot strike variants among runners in competitive road races. We classified the left and right foot strike patterns of 936 distance runners, most of whom would be considered of recreational or sub-elite ability, at the 10 km point of a half-marathon/marathon road race. We classified 88.9% of runners at the 10 km point as rearfoot strikers, 3.4% as midfoot strikers, 1.8% as forefoot strikers, and 5.9% of runners exhibited discrete foot strike asymmetry. Rearfoot striking was more common among our sample of mostly recreational distance runners than has been previously reported for samples of faster runners. We also compared foot strike patterns of 286 individual marathon runners between the 10 km and 32 km race locations and observed increased frequency of rearfoot striking at 32 km. A large percentage of runners switched from midfoot and forefoot foot strikes at 10 km to rearfoot strikes at 32 km. The frequency of discrete foot strike asymmetry declined from the 10 km to the 32 km location. Among marathon runners, we found no significant relationship between foot strike patterns and race times.     

Foot strike patterns of recreational and sub-elite runners in a long-distance road race

Abstract

Although the biomechanical properties of the various types of running foot strike (rearfoot, midfoot, and forefoot) have been studied extensively in the laboratory, only a few studies have attempted to quantify the frequency of running foot strike variants among runners in competitive road races. We classified the left and right foot strike patterns of 936 distance runners, most of whom would be considered of recreational or sub-elite ability, at the 10 km point of a half-marathon/marathon road race. We classified 88.9% of runners at the 10 km point as rearfoot strikers, 3.4% as midfoot strikers, 1.8% as forefoot strikers, and 5.9% of runners exhibited discrete foot strike asymmetry. Rearfoot striking was more common among our sample of mostly recreational distance runners than has been previously reported for samples of faster runners. We also compared foot strike patterns of 286 individual marathon runners between the 10 km and 32 km race locations and observed increased frequency of rearfoot striking at 32 km. A large percentage of runners switched from midfoot and forefoot foot strikes at 10 km to rearfoot strikes at 32 km. The frequency of discrete foot strike asymmetry declined from the 10 km to the 32 km location. Among marathon runners, we found no significant relationship between foot strike patterns and race times.     

含铬螺旋藻对肥胖大鼠体重及体脂的影响

为研究含铬螺旋藻对高脂高能量诱导的大鼠单纯性肥胖的体重和体脂的影响,本文以30只成年SD大鼠为对象,适应喂饲一周后,将其随机分为对照组(10只),高脂组(10只)和实验组即含铬螺旋藻组(10只)。饲养六周后处死。实验结果表明：六周高脂高能量膳食后,对照组和实验组体重和李氏指数无显著差异,高脂组体重和李氏指数显著高于实验组和对照组;高脂组TC、TG、LDL均高于实验组,TC、LDL值有显著性意义,TG值无显著性意义。提示高脂高能量所诱导大鼠单纯性肥胖和高脂血症以高胆固醇血症为主,含铬螺旋藻能明显改善由高脂高能量诱导的大鼠单纯性肥胖和高脂血症。     

高强度与高负荷训练对健美运动员机体影响研究

目的近年来高强度训练(HIT)与高负荷训练(HVT)模式在竞技体育的田径、游泳、皮划艇等项目中,已成为优秀运动员训练计划的重要内容。该模式也已引起世界健美界的高度关注,特别是在欧美国家,该模式已成为许多世界高水平健美运动员日常训练的重要内容。目前,在我国健美项目中还没有这方面系统的研究成果,为了跟上世界竞技健美运动发展趋势,填补我国竞技健美运动负重训练模式的研究空白,该文结合中国优秀健美运动员的体能状况对HIT与HVT模式进行了系统的研究。方法该研究根据运动生理学和运动训练学原理,对筛选的12名国内优秀男子健美运动员运用肌电采集系统、等动测力系统、三维人体扫描系统等实地测试备赛期12周训练中采取HIT与HVT模式的相关数据,通过生化监测系统,追踪受试者训练时生理生化指标的变化情况,科学评价HIT与HVT模式对运动员机体状况的影响。结果 HVT对运动员静态生理生化指标、全身骨密度没有明显影响。而备赛期采用HVT会造成瘦体质量较严重流失,全身各区域肌肉发达程度差距加大;全身脂肪虽有下降,分布也有改善,但效果不是很佳;HVT对运动员心肺功能及区域肌肉力量各项指标没有明显影响,对肌肉控制与调动能力有一定提升作用。HIT对帮助运动员保持肌肉含量及减少身体脂肪含量有非常积极作用,对身体成分的改善效果明显优于HVT;HIT对控制与调动肌肉的能力优于HVT。采用HVT每周负重训练总时间约260 min,而采用HIT每周负重训练总时间约160 min,两者相差约100 min/周,表明HIT模式效能更高。结论在备赛期,若运动员减脂的同时要减少瘦体质量,以降低级别参赛,则采用HVT模式;若运动员要最大限度保留瘦体质量、降低脂肪含量,则采用HIT模式效果相对更理想。     

围绕中医体质进行人体与食疗课程教学探讨

体质现象是人类生命现象的一种重要表现形式,它具有个体差异性、群类趋同性（群类性）与相对稳定性和动态可变性等特点。通过人体与食疗课教学,探讨我院高职学生学习中医体质9种类型和体质虚弱表现,进而学会科学选择与自身体质状况相对应饮食物,以培养学生正确的饮食习惯和心理认同感的教学过程。     

Time of day and short-duration high-intensity exercise influences on coagulation and fibrinolysis

Exercise has been demonstrated to have considerable effects upon haemostasis, with activation dependent upon the duration and intensity of the exercise bout. In addition, markers of coagulation and fibrinolysis have been shown to possess circadian rhythms, peaking within the morning (0600–1200?h). Therefore, the time of day in which exercise is performed may influence the activation of the coagulation and fibrinolytic systems. This study aimed to examine coagulation and fibrinolytic responses to short-duration high-intensity exercise when completed at different times of the day. Fifteen male cyclists (VO_2max: 60.3?±?8.1?ml?kg^?1?min^?1) completed a 4-km cycling time trial (TT) on five separate occasions at 0830, 1130, 1430, 1730 and 2030. Venous blood samples were obtained pre- and immediately post-exercise, and analysed for tissue factor (TF), tissue factor pathway inhibitor (TFPI), thrombin–anti-thrombin complexes (TAT) and D-Dimer. Exercise significantly increased plasma concentrations of TF (p?p?p?p?p?=?.004) and TFPI (p?=?.031), with 0830 greater than 1730 (p .001), while 1730 was less than 2030?h (p?=?.008), respectively. There was no significant effect of time of day for TAT (p?=?.364) and D-Dimer (p?=?.228). Power output, TT time and heart rate were not significantly different between TTs (p?>?.05); however, percentage VO_2max was greater at 1730 when compared to 2030 (p?=?.04). Due to a time-of-day effect present within TF, peaking at 0830, caution should be applied when prescribing short-duration high-intensity exercise bout within the morning in populations predisposed to hypercoagulability.     

中日竞走运动员身体形态比较及高原训练对体重、体脂的影响

１９９３年８月１３日－９月８日，中日首次在青海省多巴训练基地（海拔２３６６ｍ）进行了为期２６天的高原训练合作研究．本研究对中日各１０名（其中男女各５人）竞走运动员的身体形态以及在高原训练期间的体重、体脂进行了测定．结果表明：１．中日竞走运动员身体形态具有不同的规律和特点：即中方队员较为细高腿长、上下均匀，略呈桶状形体型；日方队员较为矮粗腿短、上宽下窄（肩宽骨盆窄），略呈倒园锥形体型特点。２．在高原训练期间，双方队员的体重、体脂变化规律也有所不同：日本队员体重下降、体脂也下降，从围度指标上也表现了下降趋势，体重的下降，主要是体脂的减少，从而使瘦体重增加，相应使运动能力得到提高；而中方队员（世居高原人）体重增加，体脂也增加，反映了适应高原训练及身体消耗方面稳定性的特点。在高原上进行训练，训练强度对体重的影响较大，应注意适当调整运动员量和加强营养的补充．     

Simulation to clarify the effect of paddling motion on the hull behavior of a single kayak in a sprint race

The cause and effect relationship between the paddling motion and the hull behavior of a kayak in a sprint race has not been sufficiently investigated. The objective of this study was to investigate the effect of the paddling motion on the hull behavior by numerical simulation. A dynamic simulation model of a paddler, paddle and hull in a single kayak, which was previously developed, was used for the simulation. One standard paddling motion and three modified motions were prepared for the simulation. Three modified motions were created based on suggestions by coaches of the Japan Olympic team. These motions were thought to be often seen in paddlers of lower skill level and, therefore, empirically considered to be typically bad motions. From the simulation results, the following findings were obtained: in the simulation of the standard paddling motion, the averaged hull velocity was 5.4 m/s. This was consistent with the actual hull velocity of 5.5 m/s. Typically bad motions which induced undesirable hull fluctuations reduced the propulsive efficiency.