Agreement between Polar and SRM mobile ergometer systems during laboratory-based high-intensity,intermittent cycling activity

Abstract

The purpose of this study was to assess the agreement between two mobile cycle ergometer systems for recording high-intensity, intermittent power output. Twelve trained male cyclists (age 31.4 ± 9.8 years) performed a single 3 min intermittent cycle test consisting of 12 all-out efforts, separated by periods of passive recovery ranging from 5 to 15 s. Power output was recorded using a Polar S710 heart rate monitor and power sensor kit and an SRM Powercrank system for each test. The SRM used torque and angular velocity to calculate power, while the S710 used chain speed and vibration to calculate power. Significant differences (P < 0.05) in power were found at 8 of the 12 efforts. A significant difference (P = 0.001) was also found when power was averaged over all 12 intervals. Mean power was 556 ± 102 W and 446 ± 61 W for the SRM and S710 respectively. The S710 underestimated power by an average of 23% with random errors of ?/÷ 24% when compared with the SRM. Random errors ranged from 36% to 141% with a median of 51%. The results indicate there was little agreement between the two systems and that the Polar S710 did not provide a valid measure of power during intermittent cycling activity when compared with the SRM. Power recorded by the S710 system was influenced greatly by chain vibration and sampling rates.     

Agreement between polar and SRM mobile ergometer systems during laboratory-based high-intensity, intermittent cycling activity

The purpose of this study was to assess the agreement between two mobile cycle ergometer systems for recording high-intensity, intermittent power output. Twelve trained male cyclists (age 31.4 +/- 9.8 years) performed a single 3 min intermittent cycle test consisting of 12 all-out efforts, separated by periods of passive recovery ranging from 5 to 15 s. Power output was recorded using a Polar S710 heart rate monitor and power sensor kit and an SRM Powercrank system for each test. The SRM used torque and angular velocity to calculate power, while the S710 used chain speed and vibration to calculate power. Significant differences (P < 0.05) in power were found at 8 of the 12 efforts. A significant difference (P = 0.001) was also found when power was averaged over all 12 intervals. Mean power was 556 +/- 102 W and 446 +/- 61 W for the SRM and S710 respectively. The S710 underestimated power by an average of 23% with random errors of */[division sign] 24% when compared with the SRM. Random errors ranged from 36% to 141% with a median of 51%. The results indicate there was little agreement between the two systems and that the Polar S710 did not provide a valid measure of power during intermittent cycling activity when compared with the SRM. Power recorded by the S710 system was influenced greatly by chain vibration and sampling rates.     

Physical demands and power profile of different stage types within a cycling grand tour

This study aims to describe the intensity and load demands of different stage types within a cycling Grand Tour. Nine professional cyclists, whom are all part of the same World-Tour professional cycling team, participated in this investigation. Competition data were collected during the 2016 Giro d’Italia. Stages within the Grand Tour were classified into four categories: flat stages (FLAT), semi-mountainous stages (SMT), mountain stages (MT) and individual time trials (TT). Exercise intensity, measured with different heart rate and power output based variables, was highest in the TT compared to other stage types. During TT’s the main proportion of time was spent at the high-intensity zone, whilst the main proportion of time was spent at low intensity for the mass start stage types (FLAT, SMT, MT). Exercise load, quantified using Training Stress Score and Training Impulse, was highest in the mass start stage types with exercise load being highest in MT (329, 359?AU) followed by SMT (280, 311?AU) and FLAT (217, 298?AU). Substantial between-stage type differences were observed in maximal mean power outputs over different durations. FLAT and SMT were characterised by higher short-duration maximal power outputs (5–30?s for FLAT, 30 s–2?min for SMT) whilst TT and MT are characterised by high longer duration maximal power outputs (>10?min). The results of this study contribute to the growing body of evidence on the physical demands of stage types within a cycling Grand Tour.     

Knowledge is power: Issues of measuring training and performance in cycling

ABSTRACT

Mobile power meters provide a valid means of measuring cyclists’ power output in the field. These field measurements can be performed with very good accuracy and reliability making the power meter a useful tool for monitoring and evaluating training and race demands. This review presents power meter data from a Grand Tour cyclist’s training and racing and explores the inherent complications created by its stochastic nature. Simple summary methods cannot reflect a session’s variable distribution of power output or indicate its likely metabolic stress. Binning power output data, into training zones for example, provides information on the detail but not the length of efforts within a session. An alternative approach is to track changes in cyclists’ modelled training and racing performances. Both critical power and record power profiles have been used for monitoring training-induced changes in this manner. Due to the inadequacy of current methods, the review highlights the need for new methods to be established which quantify the effects of training loads and models their implications for performance.     

SRM系统在短距离自行车专项能力测试与评定中的应用研究

应用场地SRM系统对上海自行车队重点队员6人的场地专项训练分阶段进行跟踪测试,以便筛选有效指标评价短距离自行车主要专项能力。结果表明,在短距离自行车爆发力评价中,最大功率和平均功率、最大频率和平均频率是反映运动能力的有效指标;平均功率和平均频率是反映力量耐力的有效指标;在对短距离自行车专项最大速度的评价中,最大频率和平均频率是反应运动能力的有效指标;而平均频率是反映高速耐力的有效指标。     

Reliability and Validity of Outcome Expectancy-Related Measures in Physical Education

The purpose of this study was to examine the reliability and validity of outcome likelihood, outcome value, and outcome expectancy using data collected from students in secondary school physical education classes. Dependent measures were examined for construct, concurrent, and predictive validity, as well as internal and temporal reliability. The results of the investigation indicated the following. First, confirmatory factor analyses for the dependent variables (outcome likelihood, outcome value, outcome expectancy) revealed a suitable fit of the data with a hypothesized factor structure. Second, significant associations between these variables and other personal beliefs and values provided sound evidence for the concurrent validity of outcome likelihood, outcome value, and outcome expectancy. Third, results of regression analyses revealed that outcome likelihood and outcome value had strong predictive validity in predicting physical activity behaviors. Finally, the internal reliabilities of self-report scales for the outcome likelihood, outcome value, and outcome expectancy over a three-semester period were satisfactory. The temporal reliabilities were also acceptable.     

最佳运动成绩与训练过程若干关系的综合分析

获取最佳运动成绩是运动员训练的最终目标。最佳成绩的取得、提高及维持都需要通过训练过程来实现。训练过程是运动员具有的潜在能力向现实竞技水平转化的时间和空间载体。运动员竞技能力水平的不断发展和训练水平相对滞后这一对矛盾的存在与不断破立,推动着训练过程不断由低级向高级发展。训练过程空间性的特征反映了竞技能力动态平衡的重要性。运动训练中运动员最佳竞技状态的时间越长,最佳运动成绩出现的机率最大。在训练过程中要以最佳成绩为导向,科学规划训练过程。探索最佳成绩出现的特征,推动训练过程发展创造最佳成绩。     

The validity and reliability of a sample of 10 Wattbike cycle ergometers

ABSTRACT

The purpose of the study was to assess the validity and inter-bike reliability of 10 Wattbike cycle ergometers, and to assess the test–retest reliability of one Wattbike. Power outputs from 100 to 1000 W were applied using a motorised calibration rig (LODE) at cadences of 70, 90, 110 and 130 rev · min^?1, which created nineteen different intensities for comparison. Significant relationships (P < 0.01, r² = 0.99) were found between each of the Wattbikes and the LODE. Each Wattbike was found to be valid and reliable and had good inter-bike agreement. Within-bike mean differences ranged from 0.0 W to 8.1 W at 300 W and 3.3 W to 19.3 W at 600 W. When taking into account the manufacturers stated measurement error for the LODE (2%), the mean differences were less than 2%. Comparisons between Wattbikes at each of the nineteen intensities gave differences from 0.6 to 25.5 W at intensities of 152 W and 983 W, respectively. There was no significant difference (P > 0.05) between the measures of power recorded in the test–retest condition. The data suggest that the Wattbike is an accurate and reliable tool for training and performance assessments, with data between Wattbikes being able to be used interchangeably.     

A six-year monitoring case study of a top-10 cycling Grand Tour finisher

This study analysed the evolution of the physical potential of a twice top-10 Grand Tour cycling finisher (Tour de France and Vuelta a España) whose training was monitored between the ages of 18 and 23 years. The world-class cyclist’s power output (PO) data and training indices were analysed over six years to determine the evolution of his record power profile and training load (TL), which were estimated by using the session rating of perceived exertion (RPE) method. The total annual duration and TL increased through six seasons by 79% and 83%, respectively. The record POs in all exercise intensity zones improved over the six years. The increases in TL, monotony (+34%) and strain (+162%) from the junior category to the world-class level significantly correlated with an improvement in his aerobic potential, which was characterised by an increase in the record POs between 5 min and 4 h. This case study of the performance level and training parameters of a world-class cyclist provides comprehensive insight into the evolution of a cyclist to the top level. Furthermore, determining the record power profile of this athlete over six competitive seasons illuminates the maturation of the physical potential of a top-10 Grand Tour finisher.     

A physiological and biomechanical comparison of over-ground,treadmill and ergometer wheelchair propulsion

Abstract

The purpose of the study was to determine which laboratory-based modality provides the most valid physiological and biomechanical representation of over-ground sports wheelchair propulsion. Fifteen able-bodied participants with previous experience of wheelchair propulsion performed a 3-minute exercise trial at three speeds (4, 6 and 8 km ? h^–1) in three testing modalities over separate sessions: (i) over-ground propulsion on a wooden sprung surface; (ii) wheelchair ergometer propulsion; (iii) treadmill propulsion at four different gradients (0%, 0.7%, 1.0% and 1,3%). A 0.7% treadmill gradient was shown to best reflect the oxygen uptake (7.3 to 9.1% coefficient of variation (CV)) and heart rate responses (4.9 to 6.4% CV) of over-ground propulsion at 4 and 6 km ? h^–1. A 1.0% treadmill gradient provided a more valid representation of oxygen uptake during over-ground propulsion at 8 km ? h^–1 (8.6% CV). Physiological demand was significantly underestimated in the 0% gradient and overestimated in the 1.3% gradient and wheelchair ergometer trials compared to over-ground trials (P<0.05). No laboratory-based modality provided a valid representation of the forces applied during OG (≥ 18.4% CV). To conclude, a 0.7% treadmill gradient is recommended to replicate over-ground wheelchair propulsion at lower speeds (4 and 6 km ? h^–1) whereas a 1.0% gradient may be more suitable at 8 km ? h^–1.     

我国女子3000m障碍的训练特征与恢复

女子3 000m障碍是北京奥运会的新项目,分析其主要训练特征,以及高强度的训练后疲劳产生的机制,并提出了消除疲劳的方法,是科学训练取得好成绩的关键。     

Evaluating Measures of Optimism and Sport Confidence

The psychometric properties of the Life Orientation Test-Revised (LOT-R), the Sport Confidence Inventory (SCI), and the Carolina SCI (CSCI) were examined in a study involving 260 athletes. The study aimed to test the dimensional structure, convergent and divergent validity, and invariance over competition level of scores generated by these instruments. Exploratory structural equation modeling (ESEM) supported the measurement models for the SCI and CSCI but favoured a two-dimensional model for the LOT-R. ESEM analyses of the total pool of 33 items indicated satisfactory divergent validity among these optimism and sport confidence measures with the only overlap occurring between the LOT-R and CSCI measures of optimism. The SCI discriminated among athletes participating at different competitive levels and emerged as the most suitable instrument for measuring individual differences in sport confidence. The CSCI emerged as a better measure of optimism in a sporting context than the more general LOT-R.     

铁人三项自行车-跑换项过程的调整与训练

探讨了造成铁人三项自行车-跑换项过程中运动员常会出现不适感的原因.呼吸肌疲劳、脱水、糖原耗竭和感受器的传导反馈调整落后于身体活动变化,引起生物力学指标的不利改变,使跑的效率下降,可能是造成不适感的主要原因.自行车赛段的骑行位置和最后阶段的蹬车频率会对换项调整产生显著影响,运动员应注意根据自己的特点确定战术.换项过程中运动员身体所承受的特殊变化提示,针对比赛中将会遇到的情况进行专门训练,可能有助于提高运动员的耐受性,加快感受器的调整适应,减小生物力学指标的不利改变,减少运动损伤.     

The relationship between inertial measurement unit-derived ‘force signatures’ and ground reaction forces during cricket pace bowling

Abstract

This study assessed the reliability and validity of segment measured accelerations in comparison to front foot contact (FFC) ground reaction force (GRF) during the delivery stride for cricket pace bowlers. Eleven recreational bowlers completed a 30-delivery bowling spell. Trunk- and tibia-mounted inertial measurement units (IMUs) were used to measure accelerations, converted to force, for comparisons to force plate GRF discrete measures. These measures included peak force, impulse and the continuous force–time curve in the vertical and braking (horizontal) planes. Reliability and validity was determined by intra-class correlation coefficients (ICC), coefficient of variation (CV), Bland–Altman plots, paired sample t-tests, Pearson’s correlation and one-dimensional (1D) statistical parametrical mapping (SPM). All ICC (0.90–0.98) and CV (4.23–7.41%) were acceptable, except for tibia-mounted IMU braking peak force (CV = 12.44%) and impulse (CV = 18.17%) and trunk vertical impulse (CV = 17.93%). Bland–Altman plots revealed wide limits of agreement between discrete IMU force signatures and force plate GRF. The 1D SPM outlined numerous significant (p < 0.01) differences between trunk- and tibia-located IMU-derived measures and force plate GRF traces in vertical and braking (horizontal) planes. The trunk- and tibia-mounted IMUs appeared to not represent the GRF experienced during pace bowling FFC when compared to a gold-standard force plate.     

自行车运动训练测试台的研制

微机控制的自行车运动员综合训练测试系统,可提供运动员在特制的训练台上骑行,台上装有模拟阻力和测速装置,还设置有脚蹬力和多种测角装置,可同步检测各种力值与角度并实时处理。骑行中由模拟显示盘显示诱导、骑行的轨迹信号和骑行参数。系统配有三套软件可进行诊断、检测和诱导。可屏幕分析或储存打印。     

Repeated sprint ability in young basketball players: one vs. two changes of direction (Part 1)

The present study aimed to compare the changes of direction on repeated sprint ability (RSA) vs. intensive repeated sprint ability (IRSA) protocols in basketball. Eighteen young male basketball players performed on RSA [10 × 30-m (15 + 15-m, one change of direction)] and IRSA [10 × 30-m (10 + 10 + 10-m, two changes of direction)]. A correlation matrix between RSA, IRSA, “squat jump (SJ)–countermovement jump (CMJ)”, footstep analysis and total distance in Yo-Yo intermittent recovery level 1 was performed. The best time, worst time, total time and the number of footsteps were significantly smaller in the RSA test compared to IRSA test (P < 0.001), even though they were significantly correlated with each other (r > 0.80, P < 0.05). Blood lactate level and fatigue index did not show any difference between tests. The sensibility of the two tests assessed by the Bland–Altman analysis revealed a small bias (<1.5%) for almost all variables. Moreover, almost all time variables of the two tests were significantly correlated with the SJ (r > 0.478, P < 0.05), CMJ (r > 0.515, P < 0.05) and Yo-Yo (r > 0.489, P < 0.05) performances. The IRSA provided a reliable method for assessing specific sprint ability (with 10-m legs for IRSA ~2.3 s vs. 15 m for RSA ~3 s) with a closer link to basketball game’s actions (~2 s). Besides, IRSA could be an appropriate choice for assessing both RSA and changes of direction capacities in basketball players.     

Relationships between lower-limb kinematics and block phase performance in a cross section of sprinters

Abstract

This study investigated lower-limb kinematics to explain the techniques used to achieve high levels of sprint start performance. A cross-sectional design was used to examine relationships between specific technique variables and horizontal external power production during the block phase. Video data were collected (200 Hz) at the training sessions of 16 sprinters who ranged in 100 m personal best times from 9.98 to 11.6 s. Each sprinter performed three 30 m sprints and reliable (all intraclass correlation coefficients, ICC(2,3) ≥ 0.89) lower-limb kinematic data were obtained through manual digitising. The front leg joints extended in a proximal-to-distal pattern for 15 sprinters, and a moderate positive relationship existed between peak front hip angular velocity and block power (r = 0.49, 90% confidence limits = 0.08–0.76). In the rear leg, there was a high positive relationship between relative push duration and block power (r = 0.53, 90% confidence limits = 0.13–0.78). The rear hip appeared to be important; rear hip angle at block exit was highly related to block power (r = 0.60, 90% confidence limits = 0.23–0.82), and there were moderate positive relationships with block power for its range of motion and peak angular velocity (both r = 0.49, 90% confidence limits = 0.08–0.76). As increased block power production was not associated with any negative aspects of technique in the subsequent stance phase, sprinters should be encouraged to maximise extension at both hips during the block phase.     

自行车场地全能赛的项目特征与训练方法

自行车场地全能赛是2012年伦敦奥运会自行车正式比赛项目,运动员在连续两天内需要完成6个小项的比赛。全能赛对运动员的专项速度和耐力素质水平均有较高要求,其中速度能力对比赛成绩的影响大于耐力,速度型运动员可能更加适合从事全能赛项目。全能赛对运动员专项能力的全面要求决定了训练的复杂性,应根据阶段训练目标和运动员的不足针对性的安排专项能力、身体力量和有氧能力训练。     

周期训练理论的基本原理及研究中的若干新问题

通过对周期训练理论基本原理的剖析，以及对其在现代运动实践中的应用与发展所作的审视，发现传统的周期训练理论并没有发生根本变化；提出为适应现代比赛赛制的变化，广大教练员在安排运动训练结构时，仍要以周期训练理论为指导，正确处理好比赛与训练的关系；认为加强训练负荷刺激及其效应的基础理论研究，是未来专项周期训练理论工作的发展方向。