Biomechanics feedback for rowing

Factors that affect boat speed are important determinants of rowing performance and should form the basis of feedback to rowers and their coaches. Biomechanical analysis of rowing has led to variables that are causally linked to boat speed. With modern technology, these variables can be measured and feedback can be presented instantaneously on-water, or be presented simultaneously with video after the event. This paper demonstrates the links between the criterion of success in rowing, the time for completing 2000 m and the forces acting on the boat, and describes an instrumentation system for providing feedback of these variables to rowers and coaches. These feedback techniques have been used with rowers from national to Olympic competition standard. Aspects of technique have been linked to the determinants of boat speed and several examples are presented here. The motor learning literature supports the effectiveness of kinetic information feedback for the improvement of motor skill and provides a relevant conceptual framework for the improvement of rowing performance. However, although rowers and their coaches value this feedback, further research must be undertaken to establish a sound basis for comparing the effectiveness of such feedback compared with traditional styles, such as verbal feedback of performance.     

Optimization of oar blade design for improved performance in rowing

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.     

The efficacy of video feedback for learning the golf swing

This study was designed to examine the efficacy of video instruction relative to that of verbal and self-guided instruction. Before training, 30 golfers were assigned at random to one of three groups: video, verbal or selfguided instruction. Video instruction was defined as a practice session in which the teacher was aided by the use of video. Verbal instruction was defined as practising with the teacher providing verbal feedback. Self-guided practice was defined as practising without the aid of a teacher. The participants had a pre-test, four 90 min practice sessions, an immediate post-test and a 2 week delayed post-test. During the pre-test and post-tests, all participants were required to strike 15 golf balls, with a 7-iron, from an artificial turf mat for distance and accuracy. The results showed that all groups were equal on the pre-test. On the first post-test, the two instruction groups performed worse than the self-guided group. However, on the second post-test, the two instruction groups performed better than the self-guided group, with the video group performing best. We interpret these results to mean that video analysis is an effective means of practice, but that the positive effects may take some time to develop.     

The influence of stretcher height on posture in ergometer rowing

Abstract

The aim of this investigation was to determine the effect on rower posture of raising the stretchers. Nine male university rowers completed a single 30-s trial at each of three stretcher heights on an ergometer, at 30 strokes min^?1. The first ten strokes with complete data were averaged and data for four time points during the stroke extracted: catch, mid-drive, finish, and mid-recovery. Ankle angle was shown to increase significantly at all points during the stroke (P<0.01) as the stretchers were raised. Knee angle was only significantly increased into a more extended posture at mid-drive (P<0.05) and mid-recovery (P<0.01) for the higher stretcher positions, hip angle was significantly reduced into a more flexed posture at the catch (P<0.05) and at mid-recovery (P<0.05), and the trunk was significantly extended at the catch (P<0.01), finish (P<0.01), and mid-recovery (P<0.05) as the stretchers were raised. Our results show that the increase in stretcher height caused the rower's body to rotate posteriorly in the sagittal plane. This we suggest reduced the vertical component of stretcher force, thus achieving a more mechanically effective position, which could have led to the slower rate of fatigue reported previously for the two raised stretcher positions (Caplan & Gardner, 2005). The increased flexion of the hip should not be ignored, however, as this may lead to overstretching of the hip extensors if the stretchers are raised too high. Further research is required to determine the extent to which the stretchers can be raised in on-water rowing.     

Power,consent and resistance: an autoethnography of competitive rowing

This study builds upon existing socio-cultural work into sports coaching by probing the meanings and varieties of the shared coach–athlete experience. Specifically, the paper utilises an autoethnographic approach in an attempt to chart the complex and dynamic relationship that existed between me, the principal author, as a rowing coxswain and my coach during the preparation for a national rowing championship. Data were drawn from a training diary, emails (both sent and received) and memories during the six months I spent with Coach. The data are presented through three separate yet inter-related stories. Here, the plot of the tale hinges on the tension between my personal perceptions of effective coaching and those employed by Coach. The findings are principally theorised through Nyberg's and Giddens’ concepts of power and resistance, as a fruitful relationship between Coach and me (and the crew) soon turned into a dysfunctional one. The conclusion emphasises the importance of recognising the power-ridden nature of coaching and the value of the autoethnographic genre in exploring it.     

Strapping rowers to their sliding seat improves performance during the start of single-scull rowing

In this study, the effect of strapping rowers to their sliding seat on performance during 75 m on-water starting trials was investigated. Well-trained rowers performed 75 m maximum-effort starts using an instrumented single scull equipped with a redesigned sliding seat system, both under normal conditions and while strapped to the sliding seat. Strapping rowers to their sliding seat resulted in a 0.45 s lead after 75 m, corresponding to an increase in average boat velocity of about 2.5%. Corresponding effect sizes were large. No significant changes were observed in general stroke cycle characteristics. No indications of additional boat heaving and pitching under strapped conditions were found. The increase in boat velocity is estimated to correspond to an increase in average mechanical power output during the start of on-water rowing between 5% and 10%, which is substantial but smaller than the 12% increase found in a previous study on ergometer starting. We conclude that, after a very short period of adaptation to the strapped condition, single-scull starting performance is substantially improved when the rower is strapped to the sliding seat.     

Strapping rowers to their sliding seat improves performance during the start of ergometer rowing

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.     

The effect of rowing to exhaustion on frontal plane angular changes in the lumbar spine of elite rowers

Abstract

Lumbar spine injury is common in rowers and examination of spinal kinematics may improve the understanding of this injury's prevalence. This study aimed to examine the range of frontal plane angular displacement (AD) in the lumbar spine at L3 during ergometer rowing and to investigate the effect of exhaustion on lumbar kinematics. Twelve elite male rowers completed an incremental test on a Concept 2 ergometer. Lumbar AD at L3 was measured continually throughout the rowing trial using a Spectrotilt Inclinometer and blood lactate was sampled at 3-minute intervals. AD of between 4.7° and 8.8° was recorded at L3. There was a significant increase in AD between the first and last stage of the test (mean increase = 4.1 ± 1.94°, 95% Confidence Interval [CI], 2.9 to 5.3°, t = 7.36, P = 0.000014). Incremental rise in AD was associated with an incremental rise in blood lactate but regression confirmed that only stroke rate was a significant predictor for increasing angle. Thus there is a statistically significant increase in frontal plane AD at L3 over the course of an incremental exercise test although it cannot be confirmed if this is as a result of exhaustion. The values of AD confirm that there is motion in the frontal plane in ergometer rowing.     

From the field of play to the laboratory: Recreating the demands of competition with augmented reality simulated sport

ABSTRACT

Biomechanical analysis has typically been confined to a laboratory setting. While attempts have been made to take laboratory testing into the field, this study was designed to assess whether augmented reality (AR) could be used to bring the field into the laboratory. This study aimed to measure knee load in volleyball players through a jump task incorporating AR while maintaining the perception-action couplings by replicating the visual features of a volleyball court. Twelve male volleyball athletes completed four tasks: drop landing, hop jump, spike jump, and spike jump while wearing AR smart glasses. Biomechanical variables included patellar tendon force, knee moment and kinematics of the ankle, knee, hip, pelvis and thorax. The drop landing showed differences in patellar tendon force and knee moment when compared to the other conditions. The hop jump did not present differences in kinetics when compared to the spike conditions, instead of displaying the greatest kinematic differences. As a measure of patellar tendon loading the AR condition showed a close approximation to the spike jump, with no differences present when comparing landing forces and mechanics. Thus, AR may be used in a clinical assessment to better replicate information from the competitive environment.     

从运动生物力学角度看抓举失败——以全国男子举重锦标赛江苏队员为例

通过立体摄像方法，从运动生物力学的角度，对成功和失败试举动作进行了对比分析。从中看出，对同一运动员尽管成功和失败抓过程中，杠铃重心都达到相同的最大高度，然而杠铃重心和人体重心的相对垂直距离是不一样的失败试举过程中，运动员没有获得足够的垂直支撑空间，在极限负荷情况下当然不能发挥出最大的支撑力量，造成失败。     

短跑着地缓冲的运动生物力学分析

对短跑的动力来源问题、缓冲时相问题、缓冲距离问题等关键性的特点问题进行探讨与分析,从生物力学的角度短跑着地缓冲的动作进行分析,并探究了影响着地缓冲的若干因素,以期完善人们对该动作的认识,服务训练。     

Biomechanics of judo backward breakfall for different throwing techniques in novice judokas

It is generally accepted that proper learning of the breakfall technique during early judo training is essential for attenuating the risk of judo-related head injury. Therefore, it is critical to understand the kinematics and head injury risks of breakfall motion to design a more safe and effective judo teaching paradigm that results in reduction of injury risk. We aimed to investigate the biomechanics of judo backward breakfalls by comparing osoto-gari and ouchi-gari in novice judokas. Twelve male novice judokas (age: 21.3 years, SD?=?0.6 years; height: 1.74?m, SD?=?0.04?m; body weight: 71.3, SD?=?6.4?kg; body mass index: 23.5, SD?=?2.3) volunteered to participate in this study. The kinematic data of the breakfall motion for both osoto-gari and ouchi-gari were collected using a three-dimensional motion analysis technique (200?Hz). We observed significant differences between the movement patterns for the two techniques, especially in the lower extremity movements. In addition, a significantly greater peak extension momentum (osoto-gari: 1.29, SD?=?0.23?kg?m^2?s^?1; ouchi-gari: 0.84, SD?=?0.29?kg?m^2?s^?1) and lower head position along the vertical axis (osoto-gari: 0.18, SD?=?0.05?m; ouchi-gari: 0.31, SD?=?0.08?m) with a large effect size were found in the breakfall for osoto-gari. Our results suggest that a different paradigm is needed for effectively teaching each breakfall technique that will enable us to substantially lower the risk of judo-related head injuries in novice judokas.     

Prediction of elite schoolboy 2000-m rowing ergometer performance from metabolic,anthropometric and strength variables

In 19 elite schoolboy rowers, the relationships between anthropometric characteristics, metabolic parameters, strength variables and 2000-m rowing ergometer performance time were analysed to test the hypothesis that a combination of these variables would predict performance better than either individual variables or one category of variables. Anthropometric characteristics, maximal oxygen uptake (V O 2m ax ), accumulated oxygen deficit, net efficiency, leg strength and 2000-m rowing ergometer time were measured. Body mass, V O 2max and knee extension correlated with 2000-m performance time (r = -0.41, -0.43 and-0.40, respectively; P 0.05), while net efficiency and accumulated oxygen deficit did not. Multiple-regression analyses indicated that the prediction model using anthropometric variables alone best predicts performance (R = 0.82), followed by the equation comprising body mass, V O 2max and skinfolds (R = 0.80). Although the regression equations increased the predictive power from that obtained using single variables, the hypothesis that a prediction model consisting of variables from different physiological categories would predict performance better than variables from one physiological category was not supported.     

足底压力测量仪器的性能及在运动生物力学研究领域的应用

足底压力及压力分布测量技术已在很多研究领域,特别是运动生物力学方面得到广泛应用。对目前比较常用的测量仪器及性能做了比较分析,并列举了在运动生物力学领域的应用实例,以达到对相关仪器主要性能指标的了解、选择及应用的目的。     

Is stroke smoothness a reliable indicator of fatigue in ergometer rowing?

A measure of stroke smoothness (SS) has been presented previously to indicate the degree to which rowers produce an “ideal” handle force profile that of the positive half of a sine wave [2]. This study aimed to determine the influence of fatigue on SS. Ten male rowers completed a maximal intensity trial. Fast Fourier transform methods were used to calculate SS which was given by the amplitude of the fundamental frequency as a percentage of the sum of the first ten peaks. Visual inspection of the data showed indications of a reduction in movement coordination as a function of fatigue. However, SS did not change significantly between the first, middle and last ten strokes (p = 0.205), despite a 21% reduction in mean power between the start and end of the trial. The results suggested that although the shape of the force profile can qualitatively indicate a reduction in movement coordination, the smoothness of the force profiles remains similar with fatigue.     

人体前臂肌腱生物力学特征实验研究

目的:研究人体前臂肌腱的生物力学特征,可为其损伤的防治、修复、人工材料替换等提供理论依据.方法:用专门仪器完成58例成人新鲜前臂肌腱"一维拉伸破坏试验",并对实验数据进行统计学处理;结果:1)前臂多数肌腱在0%～5%应变内,拉伸应力随应变缓慢增加,曲线平坦,属于曲线的"坡脚区",在8%～16%应变段,拉伸应力随应变增大而增大,变形达到20%左右,拉伸应力不再随应变增长,并且各肌腱之间极限应力与极限应变没有显著性差异;2)前臂肌腱中有部分肌腱的拉伸刚度与弹性响应两项指标,相互之间有显著性差异.结论:前臂多数肌腱在承受拉伸负荷时,应力变化特点相似,最大载荷的能力差异不大,但是抵抗变形的能力与变形的难易程度等方面有一定的差异.     

Science and medicine of rowing: A review

The biology and medicine of rowing are briefly reviewed. Effort in a 2000 -m race is about 70% aerobic. Because the boat (and in some instances a cox) must be propelled, successful competitors are very tall, with a large lean mass and aerobic power. Large hearts may lead to erroneous diagnoses of a cardiomyopathy. Large respiratory minute volumes must be developed by chest muscles that are also involved in rowing. The vital capacity is typically large, and breathing becomes entrained. Expiration cannot be slowed relative to inspiration (as normally occurs at high rates of ventilation) and the limiting flow velocity may be reached, with the potential for airway collapse. Performance is strongly related to the power output at the ‘anaerobic threshold’, and lactate measures provide a guide to an appropriate intensity of endurance training. Peak blood lactate levels are higher in males (commonly 11–19 mmol·l -1 and occasionally as high as 25 mmol·l -1) than in females (9–11 mmol·l -1), probably because males have a greater muscle mass in relation to blood volume. The skeletal muscles are predominantly slow twitch in type, developing an unusual force and power at low contraction velocities. Many rowers have a suboptimal diet, eating excessive amounts of fat. Lightweight rowers also have problems of weight cycling. Aerobic power and muscle endurance often change by 10% over the season, but such fluctuations can be largely avoided by a well-designed winter training programme. Injuries include back and knee problems, tenosynovitis of the wrist and, since the introduction of large blades, fractures of the costae.     

第十六届全国运动生物力学学术交流大会述评

第16届全国运动生物力学学术交流大会于2013年9月22-25日在广西壮族自治区桂林市广西师范大学召开.大会邀请了11位国内外知名专家学者做了相关研究的专题报告,展示了当前国际国内在运动生物力学及其相关联学术研究方面的诸多成果,为参会的各位学者、从事运动生物力学方面工作的各位技术人员、在校大学生等提供了一个很好的学习交流的机会.     

Analogy learning: A means to implicit motor learning

Two experiments were conducted to examine the hypothesis that learning by analogy will invoke characteristics of an implicit mode of motor learning. In the first experiment, table tennis novices learned to hit forehand topspin implicitly, explicitly or by analogy. The results showed that the analogy and implicit learning groups accumulated equivalently fewer explicit rules than the explicit learning group during the learning phase. When a concurrent secondary task was added, the explicit learning group suffered from a significantly more serious performance impairment than the analogy and implicit learning groups; no significant differences were seen between the latter two groups. Self-perceived performance was correlated to actual performance in the explicit learning group but not in the analogy or the implicit learning groups. In the second experiment, the performance of an explicit learning group was found to be impaired by both a stress intervention and a thought suppression intervention, whereas the performance of an analogy learning group was not. These characteristics of analogy learning parallel those reported in the implicit learning literature, suggesting that analogy learning may be an effective method for teaching skills implicitly in sport.     

运动生物力学在田径运动中的应用及前景

对运动生物力学在田径运动中的运用情况进行了针对性地归纳、分析,认为学科自身的特点和研究传统是其在该领域得以广泛应用的主要原因.文章同时从其研究现状、理论方法、研究手段等角度进行了分析、探讨,研究得出测量技术的进步和计算机技术的进一步应用是现阶段运动生物力学取得突破性发展的首要环节;充分利用力学、机能解剖学和生理学等基础学科的研究成果,并形成自己独特的理论与方法是这门学科的发展趋势.