Total kinetic energy production of body segments is different between racing and training paces in elite Olympic rowers

Total kinetic energy (TKE) was calculated for 28 Canadian national team Olympic rowers during training on water, comparing low-stroke rates (18–22 stroke/min) and high-stroke rates (32–40 stroke/min), using video analysis. Stroke duration was normalized to 100%, beginning and ending at the “catches”, with the drive phase occurring first and recovery second. Two discrete points were identified during the stroke, both occurring when the fingers had the same horizontal position as the ankles (i.e. mid-drive and mid-recovery). The ratios of recovery-to-drive TKE at these points for the entire body at low and high-stroke rates were 0.36 ± 0.34 and 1.26 ± 0.54 respectively. Significant differences were found for the lower leg, upper arm and forearm segments, and within the female groups. Low-stroke rate is a typical training pace and high-stroke rate is analogous to a race pace. This study demonstrates that TKE production during recovery in a race was not replicated during training. While training at low-stroke rates is vital for technique refinement, this study stresses the importance of training appropriately for the energy expenditure during high-stroke rate recovery. This is commonly overlooked by coaches and athletes.     

Omega Wave系统评价赛艇运动员心功能的应用研究

运用实验法、比较法等对广东省优秀赛艇运动员一周强度训练前后机体疲劳状态进行监测,通过Omega Wave系统评价运动员的心功能。结果表明:部分运动员神经疲劳程度偏高,个别运动员已产生疲劳积累。针对改善疲劳状态提出了若干建议。     

Normal training response in skeletal muscle of post-infarction heart failure patients

Abstract

Congestive heart failure (CHF) patients experience reduced muscle fatigue resistance and exercise capacity. The aim of this study was to assess whether skeletal muscle in CHF patients has a normal training response compared to healthy subjects. We compared the effect of one-legged knee extensor (1-KE) endurance training in CHF patients (n=10), patients with coronary artery disease (CAD, n=9) and healthy subjects (n=13). The training response was evaluated by comparing trained leg and control leg after the training period. The fall in peak torque during 75 maximal 1-KE isokinetic contractions revealed that CHF patients were less fatigue resistant than healthy subjects in the control leg, but not in the trained leg. Peak power and peak oxygen uptake during dynamic 1-KE exercise was ~10–16% higher in trained leg than control leg. This training response was not significant different between groups. Muscle biopsies of vastus lateralis showed that fibre type composition was not different between trained leg and control leg. Capillary density was 6.5% higher in trained leg than control leg when all groups were pooled. In conclusion, the more fatigable skeletal muscle of CHF patients responds equally to endurance training compared to skeletal muscle of CAD patients and healthy subjects.     

Reliability and validity of a new double poling ergometer for cross-country skiers

Abstract

Thirty-eight competitive cross-country skiers were divided into three groups to assess the reliability and validity of a new double poling ergometer. Group A (n = 22) performed two maximal 60-s tests, Group B (n = 8) repeated peak oxygen uptake tests on the double poling ergometer, and Group C (n = 8) performed a maximal 6-min test on the double poling ergometer and a double poling time-trial on snow. The correlation between the power calculated at the flywheel and the power applied at the base of the poles was r = 0.99 (P < 0.05). The power at the poles was 50 – 70% higher than that at the flywheel. There was a high test – retest reliability in the two 60-s power output tests (coefficient of variation = 3.0%) and no significant difference in peak oxygen uptake in the two 6-min all-out tests (coefficient of variation = 2.4%). There was a strong correlation between the absolute (W) and relative power (W · kg^?1) output in the 6-min double poling ergometer test and the double poling performance on snow (r = 0.86 and 0.89 respectively; both P < 0.05). In conclusion, our results show that the double poling ergometer has both high reliability and validity. However, the power calculated at the flywheel underestimated the total power produced and needs to be corrected for in ergonomic estimations.     

Isoperformance curves: An application in team selection

Abstract

An isoperformance curve (or surface) defines combinations of two (or more) physiological attributes of individuals such that equal performances for a specified event would be expected of them. Parameters from the two- and three-parameter critical power models are used to illustrate the concept. There are a number of sporting races where teams of individuals compete simultaneously as a unit. Rowing and team pursuit cycling are two well-known examples. Team selection may be difficult if there are more candidates available than places in the team. Based on the assumption that team members should be evenly matched with respect to performance rather than physiological attributes, proximity to a particular isoperformance curve (or surface) may suggest an obvious grouping of individuals. Isoperformance lines also enable identification of an athlete's individual training needs, since the components of the isoperformance lines can be affected by specific training interventions.     

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.     

Relative Endurance and Physiological Responses: A Study of Individual Differences in Prepubescent Boys and Adult Men

Abstract

The reliability of individual differences in relative endurance performance and physiological response was studied in prepubescent boys (N = 21) and adult men (N = 21). Subjects were tested twice (test and retest) on a relative endurance test consisting of pedalling a bicycle ergometer for 8 minutes duration at a high initial work-rate. The work-rate averaged 103% ± 1.0% VO₂ max (mean ± S.E.) for the children and 105% ± 1.1% VO₂ max for the adults, p > .05. Except for minute 3, children and adults had similar patterns for consistency of relative endurance performance (RPM). However, in comparison to adults, children had smaller individual difference variation for both VO₂ and HR (p > .05). On the average, children had a greater proportion of total variability in VO₂ (34% vs. 17%) and HR (49% vs. 13%) due to intra-individual variability in comparison to true individual differences. Children-adult differences were attributed to maturity differences.     

赛艇训练对血清尿素的影响

对赛艇运动员一次性大负荷的测功仪运动和不同强度的专项力量练习后的血清尿素的变化进行研究。实验结果显示血清尿素浓度不仅受运动强度、时间的影响．也受运动类型的影响。力量训练容易使血清尿素浓度升高;相同的练习类型与时间下,强度刺激越大,血清尿素升高越大;小强度力量训练对血清尿素有一定的清除作用。     

赛艇运动员2000m测功仪测试中主要用力肌群的表面肌电特征研究

目的:通过对湖北省男子赛艇运动员进行测功仪2 000m全力划测试,了解赛艇运动员在测功仪2 000m全力划中肌肉的发力顺序、各主要肌群力量分布比例情况、疲劳以及用力特点。研究方法:12名男子赛艇运动员测功仪2 000m全力划,测主要用力肌群的表面肌电图。结果:在测功仪2 000m全力划测试中,赛艇运动员一个完整的动作中肌肉的发力顺序为胫骨前肌>股四头肌内侧头>竖脊肌>背阔肌>三角肌后束>肱二头肌;i EMG值在比赛一开始就瞬时升高,随着比赛的进行i EMG值开始下降,到1500m处下降到最低值,而在最后冲刺阶段i EMG值达到最大值,左侧i EMG值大于右侧;从比赛开始到比赛结束,MF和MPF整体表现为随着运动负荷的增加和运动疲劳的出现呈下降的趋势,在最后冲刺阶段MF和MPF都有所增加,总的来说其下降幅度较大,增加幅度较小。     

河北省优秀赛艇运动员划桨力量—时间曲线分析

对双人双桨项目桨手上、下肢划桨力量—时间曲线进行分析,总结归纳队员划桨过程中力量不均衡、发力不协调、水下支撑长度不一致、拉桨动作欠流畅等技术问题,以期为训练效果的评估及针对性训练提供理论依据。