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.     

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.     

Strategies for the Analysis of Repeated and Multiple Measures Designs

Differentiation is made relative to repeated and multiple measure analyses. A flowchart is provided to help the researcher determine the appropriate analysis for the design of interest. Conservative tests and a multivariate approach are suggested for repeated measures designs. For designs with multiple dependent measures, the following suggestions are provided: rank reduction, Bonferroni approach, and MANOVA. Post hoc tests are also suggested once a significant multivariate F is obtained. The post hoc tests are univariate F tests, two-group breakdown, simultaneous confidence intervals, discriminant analysis, step-down analysis, and contrasts on the classification variable. It is suggested that inclusion of these more appropriate analyses will increase the internal validity of research published in the Research Quarterly.     

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.     

A real-time biomechanical feedback system for training rowers

A system was developed that quantifies rowing mechanics while an athlete trains on a rowing ergometer. The system consists of a Concept II rowing ergometer instrumented with a load cell and a series of potentiometers, a data acquisition computer and custom software. Kinematic and kinetic rowing data are displayed in the form of a two-dimensional stick figure animation, overlaid with kinematic and kinetic profiles. The software allows data to be saved and later replayed. Static and dynamic error analyses were performed to determine the accuracy and limitations of the system. Static measurements compared joint locations predicted by the RowTrainer system with values measured directly. Average static joint position errors ranged from 2 mm to −25 mm, with a typical joint location error being 10 mm. Using three-dimensional motion analysis, both dynamic and static error analyses were conducted. Average dynamic joint errors ranged from ±1 mm to −44 mm, with typical errors on the order of ±10 mm. Errors in joint positions resulted in average knee and hip joint angle errors of 9.6° and 5.8°, respectively. Additionally, the average handle horizontal velocity error during the drive phase was −1.8%.     

对轮椅车前轮举起动作的研究

轮椅车的前轮举起动作是通过肘关节的用力伸展,给予轮椅车以前进的加速度,并由此产生一个惯性力,轮椅车以后车轴为旋转中心产生旋转。目前轮椅车前轮举起动作的训练方法,主要有床架法和借助法两种。     

Three-dimensional kinematic analysis and power output of elite flat-water kayakers

The purpose was to examine power output and three-dimensional (3D) kinematic variables in the upper limbs, lower limbs and trunk in elite flat-water kayakers during kayak ergometer paddling. An additional purpose was to analyse possible changes in kinematics with increased intensity and differences between body sides. Six male and four female international level flat-water kayakers participated. Kinematic and kinetic data were collected during three tasks; low (Int_L), high (Int_H) and maximal (Int_M) intensities. No differences were observed in any joint angles between body sides, except for shoulder abduction. Significantly greater range of motion (RoM) values were observed for Int_H compared to Int_L and for Int_M compared to Int_L in trunk and pelvis rotation, and in hip, knee and ankle flexion. The mean maximal power output was 610 ± 65 and 359 ± 33 W for the male and female athletes, respectively. The stroke frequencies were significantly different between all intensities (Int_L 59.3 ± 6.3; Int_H 108.0 ± 6.8; Int_M 141.7 ± 18.4 strokes/min). The results showed that after a certain intensity level, the power output must be increased by other factors than increasing the joint angular RoM. This information may assist coaches and athletes to understand the relationship between the movement of the kayaker and the paddling power output.     

女子中跑运动员腿力与无氧运动能力关系的研究

用自行车功量计对少年中跑女运动员进行了无氧功率实验研究。结果表明,腿力与１ｓ无氧功率峰值、５ ｓ无氧功率峰值、３０ ｓ无氧功率均值、６０ ｓ无氧功率均值高度直线相关,与３０ ｓ和６０ ｓ无氧功率递减率无相关关系。提示：腿力在以高能磷酸源系统为主要供能的短时最大强度运动能力的评价中有较高的贡献率;在以乳酸能系统为主供能的稍长时间最大强度运动中,其贡献率随运动时间的延长而降低。该实验结果对最大强度和次最大强度运动项目训练手段的选择有理论指导意义     

Effects of high-intensity interval training on canoeing performance

The purpose of this study was to compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) utilizing a canoeing ergometer on endurance determinants, as well as aerobic and anaerobic performances among flat-water canoeists. Fourteen well-trained male flat-water canoeists were divided into an HIIT group or an MICT group. All subjects performed a continuous graded exercise test (GXT) and three fixed-distance (200, 500, and 1000?m) performance tests on a canoeing ergometer to determine canoeing economy, peak oxygen uptake (VO₂peak), and power at VO₂peak, and to calculate the critical velocity (CV) and anaerobic work capacity before and after the training programmes. The training programme involved training on a canoeing ergometer three times per week for four weeks. HIIT consisted of seven 2 min canoeing bouts at an intensity of 90% VO₂peak separated by 1 min of rest. The MICT group was trained at an intensity of 65% VO₂peak continuously for 20 min. After four weeks of training, performance in the 200-m distance test and the power at VO₂peak significantly improved in the HIIT group; performance in the 500?m and 1000?m distances and CV significantly improved in the MICT group. However, all variables were not significantly different between groups. It is concluded that HIIT for four weeks is an effective training strategy for improvement of short-distance canoeing performance. In contrast, MICT improves middle-distance canoeing performances and aerobic capacity.     

2005年国家男子赛艇运动员集训期间力量训练效果研究

2005年冬训期间国家男子赛艇队聘请外教伊格尔,引进大力量训练。结果显示：大力量训练有益于发展男子赛艇队员上、下肢的最大力量,上肢的力量耐力,以及速度力量。并且上肢的最大力量对6m in力量耐力的影响高于下肢和腰背部最大力量。结论：发展男子赛艇队员上肢最大力量有益于提高赛艇运动员的速度力量。