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1.
Lotte L. Lintmeijer Mathijs J. Hofmijster Guido A. Schulte Fischedick Patrick J. Zijlstra A. J. “Knoek” Van Soest 《Journal of sports sciences》2018,36(18):2138-2146
In rowing, mechanical power output is a key parameter for biophysical analyses and performance monitoring and should therefore be measured accurately. It is common practice to estimate on-water power output as the time average of the dot product of the moment of the handle force relative to the oar pin and the oar angular velocity. In a theoretical analysis we have recently shown that this measure differs from the true power output by an amount that equals the mean of the rower’s mass multiplied by the rower’s center of mass acceleration and the velocity of the boat. In this study we investigated the difference between a rower’s power output calculated using the common proxy and the true power output under different rowing conditions. Nine rowers participated in an on-water experiment consisting of 7 trials in a single scull. Stroke rate, technique and forces applied to the oar were varied. On average, rowers’ power output was underestimated with 12.3% when determined using the common proxy. Variations between rowers and rowing conditions were small (SD = 1.1%) and mostly due to differences in stroke rate. To analyze and monitor rowing performance accurately, a correction of the determination of rowers’ on-water power output is therefore required. 相似文献
2.
Brock Laschowski Cameron C. Hopkins John R. de Bruyn Volker Nolte 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(1):76-86
The deflection of rowing oar shafts subjected to a static load was investigated. Two sets of sculling oars of different design stiffness were tested at three different lengths from 2.66 to 2.70 m. Loads up to 201 N were applied to the blade end of the oar shafts, and deflections were measured at six positions along the length of the shafts. The experimental results were compared with theoretical predictions obtained by modelling the oar shafts as homogenous end-loaded cantilever beams. The results show that the oar shafts are not uniform, in contradiction to the assumed model, but rather are most compliant near the sleeves and up to 80% stiffer towards the blades. The effect of oar shaft stiffness and length on the deflection angle at the blade end of the oar shaft was at most 1.18 ± 0.01°. The measured variation of stiffness along the shaft has implications for boat propulsion and rowing performance. 相似文献
3.
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
4.
赛艇运动技术的力学原理及测试分析 总被引：8，自引：2，他引：6
从流体力学原理出发来研究如何使桨叶发挥出最大效率,讨论了桨频和拉桨幅度与推力之间的关系,进而给出了合理的运动技术形式的力学原则。研制了赛艇实船技术测试系统。利用该系统能够实时采集划船时的力量、角度、速度、加速度等,便于划船运动技术的诊断、分析赛艇运动员的专项力量特点,为运动训练的量化及科学化提供了基础。通过测试改进了运动员的技术动作,使得运动技术更加合理。 相似文献
5.
Abstract The aim of the present study was to find a more optimal blade design for rowing performance than the Big Blade, which has been shown to be less than optimal for propulsion. As well as the Big Blade, a flat Big Blade, a flat rectangular blade, and a rectangular blade with the same curvature and projected area as the Big Blade were tested in a water flume to determine their fluid dynamic characteristics at the full range of angles at which the oar blade might present itself to the water. Similarities were observed between the flat Big Blade and rectangular blades. However, the curved rectangular blade generated significantly more lift in the angle range 0 – 90° than the curved Big Blade, although it was similar between 90 and 180°. This difference was attributed to the shape of the upper and lower edges of the blade and their influence on the fluid flow around the blade. Although the influence of oar blade design on boat speed was not investigated here, the significant increases in fluid force coefficients for the curved rectangular blade suggest that this new oar blade design could elicit a practically significant improvement in rowing performance. 相似文献
6.
The aim of the present study was to find a more optimal blade design for rowing performance than the Big Blade, which has been shown to be less than optimal for propulsion. As well as the Big Blade, a flat Big Blade, a flat rectangular blade, and a rectangular blade with the same curvature and projected area as the Big Blade were tested in a water flume to determine their fluid dynamic characteristics at the full range of angles at which the oar blade might present itself to the water. Similarities were observed between the flat Big Blade and rectangular blades. However, the curved rectangular blade generated significantly more lift in the angle range 0-90 degrees than the curved Big Blade, although it was similar between 90 and 180 degrees. This difference was attributed to the shape of the upper and lower edges of the blade and their influence on the fluid flow around the blade. Although the influence of oar blade design on boat speed was not investigated here, the significant increases in fluid force coefficients for the curved rectangular blade suggest that this new oar blade design could elicit a practically significant improvement in rowing performance. 相似文献
7.
This case study reports the results of a 12-year (2005–2016) follow-up study of two Olympic champion rowers. The rowers were prospective athletes at the junior level when the study began, and we monitored their relevant physiological and performance data annually. Our findings indicated that their V?O2max gradually increased up to about 22 years of age and leveled off at a value of approximately 7 l·min?1 with minimal fluctuations thereafter. However, the variables that directly influence the V?O2max changed. There was an age-related decline in maximal heart rate of about 0.5 beats·year?1, while oxygen pulse, which serves as an indirect measure of stroke volume, correspondingly increased by about 1 ml O2·beat?1 per year, allowing the athletes to maintain exceptional V?O2max values. Maximal minute power of the studied rowers, derived each year from their ramp-wise tests, closely resembled the mean power output sustained during the 2000-m all-out tests on a rowing ergometer. A 12-year improvement of 28% and 33% occurred for the mean power output sustained over 2000 and 6000-m on a rowing ergometer, respectively. The findings contribute to the body of knowledge on athletes representing the true elites of their respective sports. 相似文献
8.
Abstract In rowing, power is inevitably lost as kinetic energy is imparted to the water during push-off with the blades. Power loss is estimated from reconstructed blade kinetics and kinematics. Traditionally, it is assumed that the oar is completely rigid and that force acts strictly perpendicular to the blade. The aim of the present study was to evaluate how reconstructed blade kinematics, kinetics, and average power loss are affected by these assumptions. A calibration experiment with instrumented oars and oarlocks was performed to establish relations between measured signals and oar deformation and blade force. Next, an on-water experiment was performed with a single female world-class rower rowing at constant racing pace in an instrumented scull. Blade kinematics, kinetics, and power loss under different assumptions (rigid versus deformable oars; absence or presence of a blade force component parallel to the oar) were reconstructed. Estimated power losses at the blades are 18% higher when parallel blade force is incorporated. Incorporating oar deformation affects reconstructed blade kinematics and instantaneous power loss, but has no effect on estimation of power losses at the blades. Assumptions on oar deformation and blade force direction have implications for the reconstructed blade kinetics and kinematics. Neglecting parallel blade forces leads to a substantial underestimation of power losses at the blades. 相似文献
9.
黄胜初 《武汉体育学院学报》2005,39(12):69-71,78
对黄胜初于2000年建立的双动力赛艇动力学方程进行矢量推导,结果显示,在操桨过程中人体质心的移动产生无击水动力。据此,认为国际赛艇联合会(FISA)赛艇教练员培训手册(2002年版)中,单动力赛艇动力模型衍生出的三点错误之处。研究认为,国内生物力学界和赛艇界对赛艇动力学及其在训练中的应用存在认识上的误区。应注重回桨技术的研究和训练,降低1桨中拉推桨时间比,提高1桨的划桨效率。 相似文献
10.
A. Millward 《Journal of sports sciences》2013,31(2):93-103
A model of the motion of a single‐scull rowing hull has been developed and verified against rowing performance data. The model was then used to explore the effect of changes in the cyclic rowing force on the boat speed. The calculations have shown that the shape of the rowing force curve and the proportion of recovery time in the total stroke can have an important effect on the boat speed. It has also been shown that a study of the fluid mechanics of the oar blade would be advantageous in determining whether a reduction in the power wasted can be obtained by changing the ratio of rowing force to normal force. 相似文献
11.
A Millward 《Journal of sports sciences》1987,5(2):93-103
A model of the motion of a single-scull rowing hull has been developed and verified against rowing performance data. The model was then used to explore the effect of changes in the cyclic rowing force on the boat speed. The calculations have shown that the shape of the rowing force curve and the proportion of recovery time in the total stroke can have an important effect on the boat speed. It has also been shown that a study of the fluid mechanics of the oar blade would be advantageous in determining whether a reduction in the power wasted can be obtained by changing the ratio of rowing force to normal force. 相似文献
12.
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
13.
Abstract Rowers sit on a seat that slides relative to the boat/ergometer. If a rower lifts him or herself from this sliding seat at any time, the seat will move away from under them and the rowing action is disrupted. From a mechanical perspective, it is clear that the need for the rower to remain in contact with the sliding seat at all times imposes position-dependent constraints on the forces exerted at the oar handle and the footstretcher. Here we investigate if the mechanical power output during rowing, which is strongly related to these forces, might be improved if the contact with the sliding seat was of no concern to the rower. In particular, we examine if elimination of these constraints by strapping the rower to the sliding seat leads to an increase in performance during the start on a standard rowing ergometer. Eleven well-trained female rowers performed 5-stroke starts in normal and strapped conditions. Handle force, vertical seat force, footstretcher force, and handle kinematics were recorded, from which mechanical power and work output were calculated. Most of the relevant mechanical variables differed significantly between the normal and strapped conditions. Most importantly, mechanical power output (averaged over the 5-stroke start) in the strapped condition was 12% higher than in the normal condition. We conclude that strapping a rower's pelvis to the sliding seat allows more vigorous execution of the stroke phases, resulting in a substantial improvement in performance during the start of ergometer rowing. 相似文献
14.
赛艇运动中拉桨阶段的桨力曲线反映了运动员的发力特征，是专项竞技能力诊断的重要途径。根据国家队的测试实例，对不同艇种、不同桨位的桨力曲线特征进行归纳分析总结，对赛艇项目进行系列测试（桨频：35桨/min），结合专项认为专项技术较好的多人艇运动员大多采用A型；双人单桨项目中．领桨手倾向于采用A型桨力-时间曲线，一号位桨手倾向于采用B型桨力-时间曲线。不同桨频下的桨力-时间曲线特征可作为训练效果的评估依据，低桨频训练必须保持合理的拉桨速度和拉桨力量。 相似文献
15.
中国赛艇优秀男子轻量级运动员技术特征分析 总被引：3，自引：1，他引：2
通过研制的赛艇实船力量测试系统对我国优秀男子轻量级运动员技术特点进行了测试分析。结果表明该系统为科学地评定、改进和完善赛艇技术提供了强有力的工具。目前我国男子轻量级多人艇技术配合上的主要问题是身体移动、停止、再启动时机不一致，身体的整体重心回位不够及时，另外，桨叶入水时拉桨不够迅速、圆滑，腿部蹬力过大。经过测试分析以后，包括老运动员在内，技术动作得到明显的改进和完善。 相似文献
16.
We evaluated (1) the test-retest reliability of the Wingate test conducted on a rowing ergometer, and (2) the sensitivity of this test in determining the differences in performance attained by 12- to 18-year-old rowers. Altogether, 297 male rowers aged 12.0-18.9 years (mean?±?s: 14.8?±?1.7) completed a maximal 30-s test on a rowing ergometer, and 80 rowers representing all age groups were retested after 5-7 days. No change was evident in participants' performance in terms of mean power output (P?=?0.726; Cohen's d?=?0.04), maximal power output (P?=?0.567; Cohen's d?=?0.06), and minimum power output (P?=?0.318; Cohen's d?=?0.11) in the second test. The intra-class correlation coefficients were high (≥0.973) and coefficients of variation were low (≤7.3%). A series of analyses of variance were used to compare the performances among 12- to 18-year-old rowers, and age-related increases in performance were evident (P?相似文献
17.
The aim of this study was to assess the effect of manipulating stroke rate on the distribution of mechanical power in rowing. Two causes of inefficient mechanical energy expenditure were identified in rowing. The ratio between power not lost at the blades and generated mechanical power (P(rower)) and the ratio between power not lost to velocity fluctuations and P(rower) were used to quantify efficiency (e(propelling) and e(velocity) respectively). Subsequently, the fraction of P(rower) that contributes to the average velocity (chi(boat)) was calculated (e(net)). For nine participants, stroke rate was manipulated between 20 and 36 strokes per minute to examine the effect on the power flow. The data were analysed using a repeated-measures analysis of variance. Results indicated that at higher stroke rates, P(rower), chi(boat), e(propelling), and e(net) increase, whereas e(velocity) decreases (P < 0.0001). The decrease in e(velocity) can be explained by a larger impulse exchange between rower and boat. The increase in e(propelling) can be explained because the work at the blades decreases, which in turn can be explained by a change in blade kinematics. The increase in e(net) results because the increase in e(propelling) is higher than the decrease in e(velocity). Our results show that the power equation is an adequate conceptual model with which to analyse rowing performance. 相似文献
18.
Matthew M. Doyle Andrew Lyttle Bruce Elliott 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):178-192
The aim of this study was to examine biomechanical variables relating to the force production of men's Lightweight (LW) and Heavyweight (HW) rowing pairs. Seven HW and seven LW coxless pairs were studied under a range of stroke rates, from 20 spm to race rating (average of 33.7 spm for the HWs and 33.9 spm for the LWs). Each crew was equipped with biomechanical apparatus allowing the measurement of gate force, horizontal oar angle, and boat velocity. The HW crews exhibited significantly higher (p < 0.05) values for all variables examined, at all rates. Peak handle force was 26.2% to 30.2% higher in the HW group. Average handle force ranged from 18.7% to 22.1% higher than the LW group. Work per stroke was found to be 26% to 28% higher for the HW crews, and Power Per Kilogram was also greater for the HW crews, from 24.0% to 29.2%. The LWs were observed to be consistently, but not significantly, slower than the HWs (from 96.9% at the race situation, to 98.7% at 28 spm). These observations are important when considering biomechanical performance indicators in rowing, as significant changes in performance indicators may lead to only minimal alteration in boat velocity. 相似文献
19.
Oar force and oar angle data resulting from a 6‐min maximal rowing ergometer test undertaken by novice (n = 9), good (n ‐ 23) and national (n = 9) level male rowers, were used to identify biomechanical performance variables which accurately discriminated between rowers of differing ability levels. The variables included two work capacity measures, mean propulsive power output per kilogram of body mass (W kg‐1) and propulsive work consistency (%), and two skill variables, stroke‐to‐stroke consistency (%) and stroke smoothness (%). Discriminant function analysis indicated the presence of two functions, both of which clearly indicated the importance of mean propulsive power output per kilogram of body mass as a discriminating variable. Function 2 gave greater weight to stroke‐to‐stroke consistency and stroke smoothness than function 1; however, function 1 was the most powerful discriminator. Classification procedures were used to predict the ability level to which a rower most likely belonged and involved defining the ‘distance’ between each rower and each ability level centroid, with the rower being classified into the ‘nearest’ ability level. These procedures indicated that 100% of the elite, 73.9% of the good, 88.9% of the novice and 82.9% of all rowers were correctly classified into their respective skill levels. Stepwise discriminant analysis included the variables in the following order: mean propulsive power output per kilogram of body mass, stroke‐to‐stroke consistency, stroke smoothness and propulsive work consistency (P < 0.001). The results of this study indicate that biomechanical performance variables related to rowing capacity and skill may be identified and used to discriminate accurately between rowers of differing skill levels, and that, of these variables, propulsive work consistency is the least effective discriminator. 相似文献
20.
Abstract The purpose of this investigation was to examine the fluid dynamic characteristics of the two most commonly used oar blades: the Big Blade and the Macon. Scaled models of each blade, as well as a flat Big Blade, were tested in a water flume using a quasi-static method similar to that used in swimming and kayaking research. Measurement of the normal and tangential blade forces enabled lift and drag forces generated by the oar blades to be calculated over the full range of sweep angles observed during a rowing stroke. Lift and drag force coefficients were then calculated and compared between blades. The results showed that the Big Blade and Macon oar blades exhibited very similar characteristics. Hydraulic blade efficiency was not therefore found to be the reason for claims that the Big Blade could elicit a 2% improvement in performance over the Macon. The Big Blade was also shown to have similar characteristics to the flat plate when the angle of attack was below 90°, despite significant increases in the lift coefficient when the angle of attack increased above 90°. This result suggests that the Big Blade design may not be completely optimized over the whole stroke. 相似文献