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1.
The aim of this study was to establish differences in intra-cyclic horizontal velocity variation of the body's centre of mass in breaststroke swimmers with flat and undulating styles. Vertical eel-like body waving and trunk rotations were measured to distinguish styles. To reconstruct trunk extension and kyphosis in the poorly visible zone close to the water surface, a semi-automated video-analysis system was developed. From 45 internationallevel swimmers examined, two groups of women and two groups of men were identified, those using the most undulating and those using the flattest styles. Among the men with the flattest style, the maximum and minimum horizontal velocity of the body's centre of mass differed by 76% from the mean swimming velocity; among the women with the most undulating style, the figure was 53%. In the most undulating style, less horizontal velocity variation of the body's centre of mass could be explained by movements of the body parts above the water surface, creating a transfer of momentum: a quick backward upper trunk rotation generates resistance and a quick forward shoulder girdle and upper arm movement, followed by a quick forward upper trunk and head rotation, generates propulsion. In addition, during an upward leg kick, some swimmers generated propulsion similar to that seen in eels.  相似文献   

2.
In a group of 699 Belgian nursing professionals, we estimated body composition using the four-component anthropometric model, relying on the equations originally formulated by Matiegka in 1921 and later revised by Drinkwater and colleagues. We estimated muscle mass using the more recent formula proposed by Martin and co-workers. A discrepancy was noted between estimated total body mass and 'assessed' mass, suggesting erroneous estimations of the components.  相似文献   

3.
Abstract

The purpose of this study was to compare Heath and Carter's anthropometric approach with the multiple regression technique for the prediction of lean body mass (LBM). Lean body mass was estimated from whole-body 40K spectrometry and body density in college-age women. Heath and Carter's second component correlates .40 with LBM (density)/height and .24 with LBM (40K)/height. The correlations are quite low and indicate that LBM per unit of height is not closely related to the second component. When lean body mass and height were used together in multiple regression analysis as separate predictors instead of a ratio, 48% of the variation was accounted for in the second component. A test of validity of the measures used to calculate Heath and Carter's second component was evaluated through the use of multiple regression analysis, incorporating height and anthropometric measures as independent variables and LBM from density and 40K as dependent variables. The muscle circumferences but not skeletal widths in the Heath and Carter method were found to be valid predictors of LBM through regression analysis. LBM is predicted with a standard error of estimate of 2.2 kg using the anthropometric variables of Heath and Carter's second component. This error is comparable to the results of other anthropometric predictions of LBM in college-age women.  相似文献   

4.
The purpose of this study was to determine the association of somatotype, body composition, and physical performance in 7- through 12-year-old boys. Two objective methods of measuring somatotype, Sheldon's trunk index method and Heath–Carter's anthropometric method, were used. Body composition was estimated as fat and lean body mass from 40K measurement, using a whole-body counter, and from two skinfold thickness measures. Physical performance measures consisted of three tests of running (mile run, 600-yd run and 50-yd dash) and two tests of jumping (standing broad jump and vertical jump). In general, somatotype components had lower correlations with running and jumping variables than did body composition or body size variables such as height, weight, and percent fat. Heath and Carter's third component, derived from the inverse ponderal index, correlated more closely with performance scores than did other components of somatotype. Somatotype components in combination with each other and with body size and body composition variables in a multiple regression analysis indicated little association with running performance, but some association with jumping. Mesomorphy and second component were the least significant somatotype components, as indicated by the standardized regression coefficients.  相似文献   

5.
Abstract

A squad of Premiership soccer players (n=24) provided informed consent to participate in this study. Using ISAK (International Society of Advancement of Kinanthropometry) accredited methods, a total of 39 measurements (sectioned as: skinfolds, girths, lengths, and breadths) were made for each player. The procedure involved three measures at each site to calculate a mean value and an acceptable technical error margin. All data collection was performed by an ISAK level 3 accredited anthropometrist. The data analysis consisted of demographic and anthropometric data, including fractionation of body mass and estimated body fat from sum of skinfolds. Scaling of the raw data was done by using the phantom strategem to obtain calculated data for inter-player comparison. Mean calculated scores for playing position were obtained. A multivariate analysis of variance revealed no differences between positions (F 15,41.810=0.783, P=0.688). Previous studies have reported heterogeneity between playing positions. However, in this study, stature and body mass were not different between strikers, midfielders, defenders, and goalkeepers. Research has suggested that a soccer player's anthropometric dimensions can be a major determinant for success within a playing position. In this study, within-position variation was quite large in some cases, which could indicate that a team that does not have the opportunity to hand-pick players, based on anthropometric characteristics, may be at a disadvantage.  相似文献   

6.
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7.
Abstract

The aim of this study was to compare equations for estimating percentage body fat from skinfold thickness in elite sport climbers by assessing their agreement with percentage body fat measured using dual-energy X-ray absorptiometry (DXA). Skinfold thickness was measured in a convenience sample of 19 elite sport climbers [9 women and 10 men; mean age 31.2 years (s = 5.0) and 28.6 years (s = 3.6), respectively]. Percentage body fat was estimated using 17 different equations, and it was also measured by DXA. A significant inter-methods difference was observed for all equations, except for Durnin's equation in men (inter-methods difference: ?0.57% and ?0.29%; 1.96 s: 5.56 and 5.23 for Siri's and Brozek's equation, respectively) and women (inter-methods difference: ?0.67% and ?1.29% for Siri's and Brozek's equation, respectively), and for Wilmore's equation using Siri's body fat equation in women (inter-methods difference: ?1.86%). In women, the limits of agreement were lower when using Durnin's equation compared with Wilmore's equation (1.96 s: 3.86% and 5.13%, respectively). In conclusion, of the 17 studied equations, Durnin's equation was the most accurate in estimating percentage body fat in both male and female elite climbers. Therefore, Durnin's equation could be used to assess percentage body fat in elite sport climbers if more accurate methods are not available. The generalizability of the results is limited by the fact that the sample was not selected at random.  相似文献   

8.
The aim of this study was to determine the effects of long-term professional golf participation on whole-body and regional bone mass and density. Dual-energy X-ray absorptiometry was performed on 15 male professional golfers and 18 sedentary individuals, matched for sex, race, age (29 ± and 25 ± 1 years, respectively), body mass (79 ± 2 and 74 ± 2 kg), height (1.78 ± 0.01 and 1.77 ± 0.02 m) and percent body fat (20 ± 2 and 21 ± 2%; mean ± s χ). We found that long-term professional golf participation is not associated with significant increments in regional or whole-body bone mass or density. Neither the lumbar spine nor the femoral neck showed any noticeable enhancement of bone mass in professional golfers compared with controls from the same population. The only effect of professional golf participation on regional body composition was a 9% increase in muscle mass in the dominant arm (P ? 0.05).  相似文献   

9.
Abstract

This study examined the agreement between estimates of thigh volume (TV) with anthropometry and dual-energy x-ray absorptiometry (DXA) in healthy school children. Participants (n=168, 83 boys and 85 girls) were school children 10.0–13.9 years of age. In addition to body mass, height and sitting height, anthropometric dimensions included those needed to estimate TV using the equation of Jones & Pearson. Total TV was also estimated with DXA. Agreement between protocols was examined using linear least products regression (Deming regressions). Stepwise regression of log-transformed variables identified variables that best predicted TV estimated by DXA. The regression models were then internally validated using the predicted residual sum of squares method. Correlation between estimates of TV was 0.846 (95%CI: 0.796–0.884, Sy·x=0.152L). It was possible to obtain an anthropometry-based model to improve the prediction of TVs in youth. The total volume by DXA was best predicted by adding body mass and sum of skinfolds to volume estimated with the equation of Jones & Pearson (R=0.972; 95%CI: 0.962–0.979; R 2=0.945).  相似文献   

10.
The ability of bioelectrical impedance analysis and anthropometry to predict fat mass and fat-free mass was compared in a sample of 82 male athletes from a wide variety of sports, using dual-energy X-ray absorptiometry (DXA) as the reference method. The percent fat measured by DXA was 10.9 - 4.9% (mean - s ), and fat mass was predicted with a standard error of the estimate of 1.7 kg for skinfolds and 2.8 kg for bioelectrical impedance analysis (P?0.001). Fat-free mass was predicted with a standard error of the estimate of 1.7 kg for anthropometry and 2.6 kg for bioelectrical impedance analysis (P?0.001). Regression of various individual skinfolds and summed skinfolds, to examine the eff ect of skinfold selection combinations by stepwise regression, produced an optimal fat mass prediction using the thigh and abdominal skinfold sites, and an optimal fat-free mass prediction using the thigh, abdominal and supra-ilium sites. These results suggest that anthropometry off ers a better way of assessing body composition in athletes than bioelectrical impedance analysis. Applying the derived equations to a separate sample of 24 athletes predicted fat and fat-free mass with a total error of 2.3 kg (2.9%) and 2.2 kg (2.7%), respectively. Combining the samples introduced more heterogeneity into the sample (n=106), and the optimal prediction of fat mass used six skinfolds in producing a similar standard error of the estimate (1.7 kg), although this explained a further 4% of the variation in DXA-derived fat. Fat-free mass was predicted best from four skinfolds, although the standard error of the estimate and coefficient of determination were unchanged.  相似文献   

11.
障碍跑     
《中华武术》2009,(6):64-64
跨越水池的生物力学分析 在跨越障碍架时,起跨腿在障碍栏架前1．50～1．80米外蹬离地面,上体前倾,微弯曲的摆动腿抬起,用脚的中部踏在横木上。上体继续降低,膝关节接近90°,带动身体重心迅速超越栏架,膝关节保持90°弯曲直到跨离障碍架,一个太小的膝角会妨碍起跨。  相似文献   

12.
A loss in total body mass during an ultraendurance performance is usually attributed to dehydration. We identified the changes in total body mass, fat mass, skeletal muscle mass, and selected markers of hydration status in 31 male nonprofessional ultratriathletes participating in a Triple Iron triathlon involving 11.4 km swimming, 540 km cycling and 126.6 km running. Measurements were taken prior to starting the race and after arrival at the finish line. Total body mass decreased by 1.66 kg (SD = 1.92; -5.3 kg to +1.2 kg; p < .001), skeletal muscle mass by 1.00 kg (SD = 0.90; -2.54 kg to +2.07 kg; p < .001), and fat mass by 0.58 kg (SD = 0.78; -1.74 kg to +0.87 kg; p < .001). The decrease in total body mass was associated with the decrease in skeletal muscle mass (r = .44; p < .05) and fat mass (r = .51; p < .05). Total body water and urinary specific gravity did not significantly change. Plasma urea increased significantly (p < .001); the decrease in skeletal muscle mass and the increase in plasma urea were associated (r = .39; p < .05). We conclude that completing a Triple Iron triathlon leads to decreased total body mass due to reduced fat mass and skeletal muscle mass but not to dehydration. The association of decrease in skeletal muscle mass and increased plasma urea suggests a loss in skeletal muscle mass.  相似文献   

13.
Abstract

Hydration status is not easily measured, but acute changes in hydration status are often estimated from body mass change. Changes in body mass are also often used as a proxy measure for sweat losses. There are, however, several sources of error that may give rise to misleading results, and our aim in this paper is to quantify these potential errors. Respiratory water losses can be substantial during hard work in dry environments. Mass loss also results from substrate oxidation, but this generates water of oxidation which is added to the body water pool, thus dissociating changes in body mass and hydration status: fat oxidation actually results in a net gain in body mass as the mass of carbon dioxide generated is less than the mass of oxygen consumed. Water stored with muscle glycogen is presumed to be made available as endogenous carbohydrate stores are oxidized. Fluid ingestion and sweat loss complicate the picture by altering body water distribution. Loss of hypotonic sweat results in increased osmolality of body fluids. Urine and faecal losses can be measured easily, but changes in the water content of the bladder and the gastrointestinal tract cannot. Body mass change is not always a reliable measure of changes in hydration status and substantial loss of mass may occur without an effective net negative fluid balance.  相似文献   

14.
ABSTRACT

The skating acceleration to maximal speed transition (sprint) is an essential skill that involves substantial lower body strength and effective propulsion technique. Coaches and athletes strive to understand this optimal combination to improve performance and reduce injury risk. Hence, the purpose of this study was to compare body centre of mass and lower body kinematic profiles from static start to maximal speed of high calibre male and female ice hockey players on the ice surface. Overall, male and female skaters showed similar centre of mass trajectories, though magnitudes differed. The key performance difference was the male’s greater peak forward skating speed (8.96 ± 0.44 m/s vs the females’ 8.02 ± 0.36 m/s, p < 0.001), which was strongly correlated to peak leg strength (R 2 = 0.81). Males generated greater forward acceleration during the initial accelerative steps, but thereafter, both sexes had similar stride-by-stride accelerations up to maximal speed. In terms of technique, males demonstrated greater hip abduction (p = 0.006) and knee flexion (p = 0.026) from ice contact to push off throughout the trials. For coaches and athletes, these findings underscore the importance of leg strength and widely planted running steps during the initial skating technique to achieve maximal skating speed over a 30 m distance.  相似文献   

15.
The aim of this study was to develop an exercise protocol to simulate tennis matchplay on a 'category 2' surface. Match analyses were used to form the basis for the design of the protocol. The protocol involved playing against a tennis ball serving machine. Part A of the protocol comprised 92 min 46 s of simulated tennis matchplay; Part B consisted of continuous hitting to the point of 'volitional fatigue' or when the required hitting frequency for two consecutive ball feeds could no longer be maintained. Ten elite tennis players (5 males, 5 females) volunteered to participate in the study, which was performed on an indoor tennis court (Matchplay?, En-Tout-Cas)?. Their age, body mass and estimated maximal oxygen uptake were as follows: males, 21.7±1.0 years, 73.6±2.6 kg and 58.0±1.7 ml?·?kg?1?·?min?1, respectively; females, 21.9±1.3 years, 62.3±2.0 kg and 42.2±0.7 ml?·?kg?·?min?1, respectively (mean±). Heart rate, change in body mass and time to volitional fatigue were monitored. The heart rate responses of the participants to the simulated matchplay (range: 140-157 beats?·?min?1, 73-81% peak heart rate) were consistent with the results of previous studies, for 'actual' matchplay. This protocol was successful in simulating similar physiological responses in Part A to 'actual' matchplay on a 'category 2' surface, in a controlled environment; it was also a sensitive evaluation tool of skilled performance in Part B. The current protocol may be used as a baseline protocol for studying the influence of, for example, training and dietary intervention on performance.  相似文献   

16.
The purpose of the study was to determine the anthropological status of elite male and female speed skaters, who were members of the 1985–7 Canadian national teams. The data were compared to those for a control group of University students. The subjects were 8 males and 6 females between 19 and 27 years of age. Nine breadth, 14 girth, 16 length and 15 skinfold measurements were used to compute parameters of body build and the composition; corrected diameters, masses, volumes and fat‐free volumes of the upper arm, forearm, thigh and calf. The speed skaters were found to be similar in body height and mass (males: 178 ± 7.6 cm and 75.5 ± 5.5 kg, females: 165.8 ± 3.8 cm and 62.3 ± 5.8 kg) to the student controls, but they had relatively and absolutely shorter legs and longer trunks. The speed skaters had a lower amount of body fat and higher FFM than their respective student controls and significantly greater relative (P ≤ 0.01) and absolute (P ≤ 0.05) total muscle mass. Analysis of composition within segments indicated that the additional muscle mass is located entirely in the lower extremity. The volume and mass of the thigh was greater (P ≤ 0.01 for the males) than that of the respective controls while the estimated volume of fat was lower. The female speed skaters were found to have more fat on their thigh than either the male speed skaters or male controls. The corrected diameter and mass of the thigh were greater (with respect to the sex) than those reported for 400 m sprinters, marathon runners, cross‐country skiers and figure skaters. The results of the initial assessment were compared to the two consecutive tests of the men's team (conducted 8 and 12 months later) and to one repeated test of the women's team (3 months later). Changes were recorded in skinfold measurements and the muscle component of the thigh.  相似文献   

17.
Abstract

Aspects of team players' performance are negatively affected when ~ 2% body mass is lost by perspiration. Although such dehydration is likely reached during summer practice in outdoors sports, it is unclear if such dehydration is achieved during the practice of indoor sports. We assessed the fluid and electrolyte deficits of elite team players during practice for the following indoor sports: indoor soccer (n=9), basketball (n=11), volleyball (n=10), and handball (n=13). Morning hydration status was estimated by measuring urine specific gravity. Sweat rate was calculated from body mass changes and fluid intake. Sweat sodium concentration from the forearm was used to estimate whole-body sodium losses. Over 91% of the players were moderately hypohydrated (urine specific gravity>1.020) at waking 3 h before practice. Indoor soccer players sweated at a higher rate (1.8 litres · h?1) than volleyball and handball players (1.2 and 1.1 litres · h?1, respectively; P<0.05), whereas sweat rate was not different between basketball players (1.5 litres · h?1) and the other team sport players (P>0.05). In average, 62±13% of sweat losses were replaced and teams' body mass loss did not exceed 1.2±0.3%. Sodium losses were similar among teams, averaging 1.2±0.2 g. The exercise fluid replacement habits of professional indoor team players are adequate to prevent 2% dehydration. However, most players could benefit from increasing fluid intake between workouts to offset the high prevalence of morning hypohydration.  相似文献   

18.
新时期我国社会体育指导员发展的问题与策略   总被引：1，自引：0，他引：1  
采用文献资料、逻辑分析等方法,探讨我国大众体育主要具有健身方法、手段的科学性、管理组织的网络性以及健身内容的多样性等特征,分析了我国社会体育指导员的管理体制、培养体制及队伍结构等存在的问题,提出了新时期我国社会体育指导员发展策略。  相似文献   

19.
全面建设小康社会时期的大众体育发展趋势分析   总被引：4，自引：1，他引：3  
方千华 《福建体育科技》2004,23(1):12-14,20
采用文献资料、逻辑分析等方法,探讨我国大众体育的发展趋势,结果表明我国大众体育具有推广的普及化、健身的科学化、管理的法制化、产业的市场化、活动的多样化、投入的扩大化、组织的网络化、群体的老龄化八大趋势,为建立全面建设小康时期的大众体育理论体系提供参考资料和理论依据。  相似文献   

20.
Abstract

A uniform measure of the gender-related differential performance of female and male Olympic and World champions is proposed: relative power output applied to the environment. Laws of physics are employed to derive equations for estimating relative power output. In previous controlled laboratory studies, equally trained male and female athletes were shown to have a relative power output not significantly different from relative lean body mass. As to the estimated power output for 32 Olympic and World championship events contested between 1976 and 2004, eight in running, four in speed skating, three in jumping, twelve in swimming and five in rowing: 100% of the 32 event mean percentage differences in power output and 96% of the 411 event percentage differences in power output are within one standard deviation of the appropriate lean body mass percentage difference, consistent with equality of training. For 1952 – 1972, significantly higher percentage differences in power output are estimated in running and swimming compared with 1976 – 2004, consistent with women being less well trained than men during that earlier period. It is noted that efforts in recent years to provide equality of opportunity for female athletes coincide with equalization of estimated relative power output in competition with the relative lean body mass.  相似文献   

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