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.     

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.     

Influence of foot-stretcher height on rowing technique and performance

Strength, technique, and coordination are crucial to rowing performance, but external interventions such as foot-stretcher set-up can fine-tune technique and optimise power output. For the same resultant force, raising the height of foot-stretchers on a rowing ergometer theoretically alters the orientation of the resultant force vector in favour of the horizontal component. This study modified foot-stretcher heights and examined their instantaneous effect on foot forces and rowing technique. Ten male participants rowed at four foot-stretcher heights on an ergometer that measured handle force, stroke length, and vertical and horizontal foot forces. Rowers were instrumented with motion sensors to measure ankle, knee, hip, and lumbar–pelvic kinematics. Key resultant effects of increased foot-stretcher heights included progressive reductions in horizontal foot force, stroke length, and pelvis range of motion. Raising foot-stretcher height did not increase the horizontal component of foot force as previously speculated. The reduced ability to anteriorly rotate the pelvis at the front of the stroke may be a key obstacle in gaining benefits from raised foot-stretcher heights. This study shows that small changes in athlete set-up can influence ergometer rowing technique, and rowers must individually fine-tune their foot-stretcher height to optimise power transfer through the rowing stroke on an ergometer.     

不同的空中姿态对摸高成绩的影响

用一维重心板对两名体育系大学生进行了四种不同姿态重心位置的测试，结合人体重心上抛运动规律，对不同空中姿态下的摸高成绩影响幅度进行了测算，结果表明，空中姿态对摸高成绩有影响；摸高成绩以直腿单手上举为最高，而以屈双腿双手上举为最底，两的差值在30cm左右。姿态对摸高的影响幅度占摸高成绩的10％左右：在影响幅度上，下肢姿态比上肢更重要；男子与女子间表现出无明显的差异。     

A comparison of electromyography and stroke kinematics during ergometer and on-water rowing

Abstract

This study assessed muscle recruitment patterns and stroke kinematics during ergometer and on-water rowing to validate the accuracy of rowing ergometry. Male rowers (n = 10; age 21 ± 2 years, height 1.90 ± 0.05 m and body mass 83.3 ± 4.8 kg) performed 3 × 3 min exercise bouts, at heart and stroke rates equivalent to 75, 85 and 95% V?O₂peak, on both dynamic and stationary rowing ergometers, and on water. During exercise, synchronised data for surface electromyography (EMG) and 2D kinematics were recorded. Overall muscle activity was quantified by the integration of rmsEMG and averaged for each 10% interval of the stroke cycle. Muscle activity significantly increased in rectus femoris (RF) and vastus medialis (VM) (P <0.01), as exercise intensity increased. Comparing EMG data across conditions revealed significantly (P <0.05) greater RF and VM activity during on-water rowing at discrete 10% intervals of stroke cycle. In addition, the drive/recovery ratio was significantly lower during dynamic ergometry compared to on-water (40 ± 1 vs. 44 ± 1% at 95%, P <0.01). Results suggest that significant differences exist while comparing recruitment and kinematic patterns between on-water and ergometer rowing. These differences may be due to altered acceleration and deceleration of moving masses on-ergometer not perfectly simulating the on-water scenario.     

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.     

Sagittal plane motion of the lumbar spine during ergometer and single scull rowing

Lumbar spine injury in rowers is common and ergometer rowing has been cited as a risk factor for this injury. The purpose of this study is to compare lumbar kinematics between ergometer and single scull rowing and to examine the effect of fatigue on kinematics. The sagittal lumbar spine motion of 19 elite male rowers (lumbar spine injury free in the previous six months) was measured with an electrogoniometer during a ‘step test’ on an ergometer and in a single sculling boat. Maximum range of lumbar flexion was recorded in standing for reference. Power output and heart rate were recorded during the ergometer tests. Heart rate was used as a surrogate for power output in the sculling test. Maximum lumbar flexion increased during the step test and was significantly greater on the ergometer (4.4° ± 0.9°change), compared with the boat (+1.3° ± 1.1°change), (3.1°difference, p = 0.035). Compared to the voluntary range of motion, there is an increase of 11.3% (ergometer) and 4.1% (boat). Lumbar spine flexion increases significantly during the course of an ergometer trial while changes in a sculling boat were minimal. Such differences may contribute to the recent findings linking ergometer use to lower-back injury.     

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.     

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.     

A mathematical model for power output in rowing on an ergometer

A mathematical model relating power output of rower to stroke rate on an ergometer (the Concept II Indoor Rower TM, Model C) is studied. The model is used to analyse the ergometer performance of a particular rower. It is determined that he can be more efficient (i.e. decrease power output while maintaining fixed velocity) by decreasing stroke rate, but at the expense of increasing force during the drive. It is also shown that he can be more efficient by increasing the drag factor (using higher vent setting) without increasing force. Dependence of power output on rowing style (the shape of the force curve) is also examined. It is shown that variation of force during the drive has little effect on efficiency, but efficiency is reduced by asymmetry of the force curve that favours the legs.     

High reliability of performance of well-trained rowers on a rowing ergometer.

High retest reliability is desirable in tests used to monitor athletic performance, but the reliability of many popular tests has not been established. The aim of this study was to determine the reliability of performance of a 2000-m time-trial lasting approximately 7 min performed on a Concept II rowing ergometer. Eight well-trained rowers (peak oxygen uptake 61+/-5 ml x kg(-1) x min(-1); mean +/- standard deviation) performed the time-trials on three occasions at 3-day intervals. Mean power (313+/-38 W in trial 1) improved by 2.3% (95% confidence interval 0.1 to 4.5%) in trial 2 and by a further 0.9% (-1.4 to 3.3%) in trial 3. The variability of performance for individual rowers expressed as a coefficient of variation for mean power was 2.0% (1.3 to 3.1%), and the retest correlation was 0.96 (0.87 to 0.99). Variability and changes in performance expressed as time to complete the test were approximately one-third those of mean power, apparently because simulated velocity is proportional to the cube root of power on this ergometer. Such high reliability makes this combination of ergometer, athlete and test protocol very suitable for monitoring rowing performance and for investigating factors that affect performance in short, high-intensity endurance events.     

体育比赛中的体态语言初探

依据体态语言理论,阐述体育比赛中的体态语言,并对其特点、影响因素以及在训练中应注意的事项进行了初步探讨     

Caution: The use of an electromagnetic device to measure trunk kinematics on rowing ergometers

The aim of the study was to determine the accuracy and variability of an electromagnetic device in measuring spinal kinematics on a traditional and replica rowing ergometer. Kinematic data collected from the 3-Space Fastrak^TM system using a Standard Concept II ergometer were compared with a replica ergometer that was in part, composed of non-ferrous materials (modified ergometer). The Fastrak's sensors were fixed to a wooden “spine” with known angles (as measured by an inclinometer). The mean inclinometer angle from four sensors (1 ± 0.2°) was significantly different than the mean angle recorded on the standard ergometer ( ? 5.4 ± 3.4°) (p = 0.007) whilst the angles recorded on the modified ergometer (1.4 ± 0.8°) were statistically equivalent to the inclinometer recordings (p = 0.660). These results indicate that the presence of ferrous material in a standard ergometer reduced the accuracy and increased the variability of data collected with the electromagnetic device. However, information collected on largely non-ferrous ergometers can provide coaches, biomechanists and clinicians with a quick and effective way to measure trunk kinematics during ergometer rowing.     

滑行姿势和功率对速滑成绩的影响

通过影像测量方法，探讨了速滑姿势与能量输出之间的关系。结果认为：功率与步频和滑行姿势密切相关；在滑行同一距离项目中，输出功率总量决定水平相近的运动员之间成绩上的微小差异：绝对意义的低姿势只能是躯干保持水平位置，而相对意义的低姿势以发挥下肢蹬伸力量为前提；高的能量输出主要是通过大量的蹬伸做功而产生。     

Visual and postural control of an arbitrary posture: The handstand

Abstract

The aim of this study was to increase our understanding of postural regulation by analysing an arbitrary posture – the handstand. We assessed the relative influence of peripheral vision and central visual anchoring on the postural balance of gymnasts in the inverted-stand posture. Displacements of the centre of pressure, the angles between the body segments, and the gymnast's height in the handstand were analysed. Postural regulation in the handstand appeared to be organized according to a system similar to that in erect posture, with three articular levels suggesting the existence of a typical organization of human posture. Moreover, both intra-modal (central and peripheral vision) and inter-modal sensory systems (vision and other balance systems) contributed to the postural regulation. The results are interpreted in terms of an ecological approach to posture in which postural regulation can be considered as an emergent phenomenon.     

Influence of lower leg muscle fatigue on the centre of pressure in a static upright posture

Abstract

We examined the influence of fatigue in the lower leg muscles on the centre of pressure sway during a static upright posture. Twelve healthy young men and women completed the exercise stress test on the triceps surae muscle and continued the exercise until their muscles were fatigued. A centre of pressure sway of 1 min was carried out in a Romberg posture at rest and at different instants after fatiguing exercise: immediately after, 5 min after, and 10 min after exercise. Blood lactate concentration was measured from fingertip samples taken before and immediately after exercise. To evaluate body sway, the following four centre of pressure sway factors were selected: unit time sway, front–back sway, left–right sway, and high-frequency band power spectrum. The measurement device used was an Anima stabilometer (G5500). The data sampling frequency was 20 Hz. After exercise, blood lactate concentration was increased. Significant differences were observed in unit time sway, front–back sway, and high-frequency band power spectrum immediately after exercise. These values eventually returned to baseline levels 5 min after fatiguing exercise.     

Relationship between 2000-m rowing ergometer performance times and World Rowing Championships rankings in elite-standard rowers

Abstract

In this study, we evaluated the extent to which 2000-m rowing ergometer performance times predicted final rankings at the World Rowing Championships in a sample of 638 rowers of both sexes and body-mass classifications (i.e. open-category and lightweight rowers). Rowing ergometer performance times were examined using a questionnaire, and in 17 of 23 events they were positively correlated (P ≤ 0.049) with the final rankings at the Championships. The highest correlations were for the ergometer performance times achieved by rowers in lightweight men's single sculls (r = 0.78; P = 0.005), women's single sculls (r = 0.75; P = 0.002), men's single sculls (r = 0.72; P = 0.004), and lightweight men's double sculls (r = 0.72; P < 0.001). We used linear regression to establish regression equations to predict final rankings based on 2000-m rowing ergometer performance times for each event in which there was a correlation greater than r = 0.50. Although correlations in 12 events met this criterion, the large standard errors of the estimate hindered ranking predictions in all of the studied events. Regression equations could be used to determine the most probable 2000-m ergometer performance time for a rower to achieve specific rankings at the World Rowing Championships.     

Asymmetry in elite rowers: effect of ergometer design and stroke rate

Between limb movement asymmetries and foot force production asymmetries are thought to be detrimental for both rower's performance and risk of injury, particularly when rowing frequently on ergometers. Several ergometers with different designs can be used by rowers as part of their indoor training. Hence, this study aimed to compare asymmetries in lower limb joint kinematics and foot force production with respect to ergometer design and rowing intensity. A new symmetry index was proposed to assess these asymmetries in elite rowers during a test on three ergometers. Additionally, the asymmetry in lower limb length was assessed to investigate its relationship with kinematic and kinetic asymmetries. Parameters describing medium (5–10%) or high (>10%) asymmetries were compared between rowing ergometers and intensities. Results indicated medium asymmetries for the ankle joint angle and hip–knee joint accelerations and high asymmetries for the resultant force and the ankle joint acceleration associated with a low inter-stroke variability. Kinetic asymmetry was neither correlated to kinematic asymmetry nor with lower limb length asymmetry. The use of a mobile ergometer led to higher joint acceleration asymmetries. Further studies are necessary to investigate the relation between these findings and muscular adaptations that may increase the risk of lower-back injury.     

对中学健美操运动员身体基本姿态训练的研究

良好的基本姿态是健美操训练的基础,对身体基本姿态训练的重要性及必要性进行了分析,总结了基本姿态训练的方法,包括站立姿态的训练、身体主要部位基本姿态训练,以及把大众健美操基本动作作为基本姿态的训练手段等.