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1.
This study compares the instrumentation and analysis techniques used when determining the power expended pedalling a rope-braked ergometer manufactured by Monark (Sweden) during a low intensity test. Power values were generated by eight subjects. The instrumentation consisted of load cells to measure the rope brake forces, a tachometer to measure the flywheel velocity and instrumented pedal cranks manufactured by Schoberer Rad Messtechnik (SRM). The subjects pedalled a rope-braked ergometer at 60 rev min-1, against a resistance of 3 kg, for 5 minutes. Three different measurements of the mean power were recorded and these were compared with the value given by Monark. The SRM cranks provided two sets of results using different software packages supplied with the cranks. SRM standard software is used for taking measurements during training and cycle races over long time periods. An additional piece of software is provided by SRM called Ptnew, which gives readings of torque and pedal cadence over periods up to 30 seconds. Using the values supplied by Monark each subject generated 180 W of power. The mean power for the eight subjects, measured using the SRM cranks, was 170.36 W (SD 4.11) using the alternative SRM software (Ptnew) over a 30 second period and 173.68 W (SD 2.21) using the standard SRM software. From the direct measurement of the brake forces and flywheel velocity the mean power across the eight subjects was 148.90 W (SD 5.89). The SRM cranks measure the input power, whereas the direct measurement system measures the power output excluding mechanical losses. These values give a figure for the mechanical efficiency for the roped-braked ergometer of 88%. It was found that Monark overestimates the power generated by the subjects when compared with both the SRM systems and the direct measurement instrumentation.  相似文献   

2.
Competitive track cycling races are won by milliseconds, and the regulation of an athlete’s power output is an important factor in performance. The aim of this study was to use a mathematical model to predict finishing times for different pacing strategies for the individual pursuit (IP), to identify the optimal strategy in terms of fastest finishing time. Power profiles were generated for a number of common pacing strategies used in cycling, which were based on actual SRM power data for an elite, male, IP cyclist for whom the average power, maximum power, total work done and actual finishing time were known. The total work output was the same for all strategies and the finishing time was predicted using a mathematical model developed previously. The results showed that, of the strategies tested, an initial “all-out” high power acceleration phase followed by a lower constant power output produced the fastest finishing time for a 4,000 m IP event, and that the time spent in the initial high power acceleration phase had a significant effect on performance.  相似文献   

3.
米卫国 《体育科研》2010,31(1):77-79
采用加速度传感仪来分析射击射箭项目的专项技术特点,通过相关部位的加速变化曲线来反映专项技术动作的稳定性及时相等特征,方法新颖,具有良好的可行性。实践说明,进一步提高加速度传感仪的精度、适宜频率、教据侍输方式及校准方法等将是方法本身在射击射箭项目中深入应用的发展方向。  相似文献   

4.
Fourteen elite and 14 amateur athletes were subjected to vibratory stimulation during bilateral biceps curl exercises of explosive strength exertion. The athletes performed two separate series of three sets of exercises in random order. The second set of one series was administered with superimposed vibration of 44 Hz and an acceleration of about 30 m x s(-2) transmitted through the two-arms handle to the arm muscles. The mechanical power of each repetition was measured by the 'Power Teach' instrument. The maximal and mean power values for each set were automatically recorded and shown on the screen. The acute effect was evaluated as the difference between the mean and peak power output in the second (with vibratory stimulation) and first (without vibratory stimulation) sets. Similarly, the residual effect was taken to be the difference between the power values of the third (after vibratory stimulation) and the first (before vibratory stimulation) sets. The results were subjected to a repeated-measures analysis of variance with group as a between-participants factor. The results showed that exercise mode (with vs without vibratory stimulation) resulted in a significant immediate effect for mean power and for maximal power. The factor group (elite vs amateurs) resulted in a significant effect for maximal power only. The increase in explosive strength exertion attributed to vibratory stimulation was 30.1 and 29.8 W (10.4% and 10.2%) for maximal and mean power respectively in the elite group, and 20.0 and 25.9 W (7.9% and 10.7%) respectively in the amateur athletes. Vibratory stimulation resulted in an insignificant residual effect.  相似文献   

5.
In this study, we assessed the agreement between the powers recorded during a 30 s upper-body Wingate test using three different methods. Fifty-six men completed a single test on a Monark 814E mechanically braked ergometer fitted with a Schoberer Rad Messtechnik (SRM) powermeter. A commercial software package (Wingate test kit version 2.21, Cranlea, UK) was used to calculate conventional and corrected (with accelerative forces) values of power based on a resistive load (5% body mass) and flywheel velocity. The SRM calculated powers based on torque (measured at the crank arm) and crank rate. Values for peak 1 and 5 s power and mean 30 s power were measured. No significant differences (P >0.05) were found between the three methods for 30 s power values. However, the corrected values for peak 1 and 5 s power were 36 and 23% higher (P <0.05) respectively than those for the conventional method, and 27 and 16% higher (P <0.05) respectively than those for the SRM method. The conventional and SRM values for peak 1 and 5 s power were similar (P >0.05). Power values recorded using each method were influenced by sample time (P <0.05). Our results suggest that these three measures of power are similar when sampled over 30 s, but discrepancies occur when the sample time is reduced to either 1 or 5 s.  相似文献   

6.
Plyometric jumping is a commonly prescribed method of training focused on the development of reactive strength and high-velocity concentric power. Literature suggests that aquatic plyometric training may be a low-impact, effective supplement to land-based training. The purpose of the present study was to quantify acute, biomechanical characteristics of the take-off and flight phase for plyometric movements performed in the water. Kinetic force platform data from 12 young, male adults were collected for counter-movement jumps performed on land and in water at two different immersion depths. The specificity of jumps between environmental conditions was assessed using kinetic measures, temporal characteristics, and an assessment of the statistical relationship between take-off velocity and time in the air. Greater peak mechanical power was observed for jumps performed in the water, and was influenced by immersion depth. Additionally, the data suggest that, in the water, the statistical relationship between take-off velocity and time in air is quadratic. Results highlight the potential application of aquatic plyometric training as a cross-training tool for improving mechanical power and suggest that water immersion depth and fluid drag play key roles in the specificity of the take-off phase for jumping movements performed in the water.  相似文献   

7.
Fourteen elite and 14 amateur athletes were subjected to vibratory stimulation during bilateral biceps curl exercises of explosive strength exertion. The athletes performed two separate series of three sets of exercises in random order. The second set of one series was administered with superimposed vibration of 44 Hz and an acceleration of about 30 m .s-2 transmitted through the two-arms handle to the arm muscles. The mechanical power of each repetition was measured by the ‘Power Teach’ instrument. The maximal and mean power values for each set were automatically recorded and shown on the screen. The acute effect was evaluated as the difference between the mean and peak power output in the second (with vibratory stimulation) and first (without vibratory stimulation) sets. Similarly, the residual effect was taken to be the difference between the power values of the third (after vibratory stimulation) and the first (before vibratory stimulation) sets. The results were subjected to a repeated-measures analysis of variance with group as a between-participants factor. The results showed that exercise mode (with vs without vibratory stimulation) resulted in a significant immediate effect for mean power and for maximal power. The factor group (elite vs amateurs) resulted in a significant effect for maximal power only. The increase in explosive strength exertion attributed to vibratory stimulation was 30.1 and 29.8 W (10.4% and 10.2%) for maximal and mean power respectively in the elite group, and 20.0 and 25.9 W (7.9% and 10.7%) respectively in the amateur athletes. Vibratory stimulation resulted in an insignificant residual effect.  相似文献   

8.
In this study, we assessed the agreement between the powers recorded during a 30?s upper-body Wingate test using three different methods. Fifty-six men completed a single test on a Monark 814E mechanically braked ergometer fitted with a Schoberer Rad Messtechnik (SRM) powermeter. A commercial software package (Wingate test kit version 2.21, Cranlea, UK) was used to calculate conventional and corrected (with accelerative forces) values of power based on a resistive load (5% body mass) and flywheel velocity. The SRM calculated powers based on torque (measured at the crank arm) and crank rate. Values for peak 1 and 5?s power and mean 30?s power were measured. No significant differences (P?>0.05) were found between the three methods for 30?s power values. However, the corrected values for peak 1 and 5?s power were 36 and 23% higher (P?<0.05) respectively than those for the conventional method, and 27 and 16% higher (P?<0.05) respectively than those for the SRM method. The conventional and SRM values for peak 1 and 5?s power were similar (P?>0.05). Power values recorded using each method were influenced by sample time (P?<0.05). Our results suggest that these three measures of power are similar when sampled over 30?s, but discrepancies occur when the sample time is reduced to either 1 or 5?s.  相似文献   

9.
The use of cycle ergometers with strain gauges bonded on to the cranks enables the evaluation of strength, velocity and power. However, the torque measured at the end of downstroke is higher at high velocity than at medium velocity in contradiction with the force–velocity relationship. Kinematic data were collected with a camera during sprints on a Lode ergometer with strain gauges. Leg mechanical energy (E Leg) and its derivative (dE Leg/dt) were calculated from the sum of the kinetic and potential energies. The opposition of P ext (output at crank level) and dE Leg/dt before bottom dead centre suggested a transformation of E Leg into external work, explaining the higher torque at the end of downstroke at peak velocity. Another explanation is that the leg muscles worked on different parts of their torque–angle relationships as the phase between knee and ankle angles was different at low and high cycling frequencies. Musculo-skeletal net power output (algebraic sum of P ext and dE Leg/dt) indicated that musculo-skeletal structures participated in the upward movement, whereas P ext was negative.  相似文献   

10.
This study aimed to determine if the Garmin Vector (Schaffhausen, Switzerland) power meter produced acceptable measures when compared with the Schoberer Rad Messetechnik (SRM; Julich, Germany) power meter across a range of high-intensity efforts. Twenty-one well-trained cyclists completed power profiles (seven maximal mean efforts between 5 and 600 s) using Vector and SRM power meters. Data were compared using assessments of heteroscedasticity, t tests, linear regression, and typical error of estimate (TEE). The data were heteroscedastic, whereby the Vector pedals increasingly overestimated values at higher power outputs; however, t tests did not identify any significant differences between power meters (p > .05). Using linear regression, Vector data were fit to an SRM equivalent (slope = .99; intercept = ?9.87) and TEE produced by this equation was 3.3% (3.0%–3.8%). While the data shows slight heteroscedasticity due to differing strain-gauge placement and resultant torque measurement variance, the Vector appears acceptable for measures of power output across various cycling efforts.  相似文献   

11.
The aim of this study was to describe and validate a new cycling ergometer with original characteristics that allow the measurement of biomechanical variables with position and crank inertial load used by the cyclist in field condition. The braking pedalling force, that permitted the simulation of the resistance to the cyclist in the field, is performed with a brushless electric motor. The validity and the reproducibility of the power output measurements were compared with the widely accepted SRM powermeter. The results indicate that taking into account a systematic error, the measurements are valid compared with the SRM, and the reproducibility of the power output measurements is similar to the SRM. In conclusion, this ergometer is the only one that allows at the same time for (1) valid and reproducible power output measurements at submaximal intensity, (2) utilisation of the personal bicycle of the cyclist, and (3) simulation of the inertial characteristics of the road cycling.  相似文献   

12.
通过对上海市男子短距离自行车运动员在10运会前一年的比赛、训练情况进行连续追踪，应用SRM训练系统对运动员在训练和比赛情况进行分析，对SRM训练系统在自行车运动员专项力量训练中的应用进行了探讨，结果发现：（1）使用SRM训练系统可以监测自行车运动员比赛或训练中的实时情况，通过功率、速度以及频率等指标，可以反映自行车运动员专项能力的变化情况。（2）自行车运动员的运动成绩取决于专项力量的大小，而不是绝对力量的高低。（3）自行车运动员的专项力量是在自行车运动中表现出来的一种高频率的踏蹬力量。  相似文献   

13.
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.  相似文献   

14.
The metabolic cost of locomotion at any given speed, when expressed per kilogram of body mass, is greater for children than for older individuals. Incomplete explanations for the age-related difference motivated this study, which used a multidisciplinary method to examine metabolic, kinematic and electromyographic data from three maturational groups of children. Thirty children aged 7-8 (n = 10), 10-12 (n = 10) and 15-16 (n = 10) years completed 4 min bouts of submaximal treadmill exercise at six speeds--two walking and four running--assigned in random order. Metabolic (net VO2), kinematic (total body mechanical power, energy transfer rates, stride rate) and electromyographic (co-contraction of agonist and antagonist muscles in thigh and leg segments) data were collected. Multiple regression analysis was performed with net VO2 or efficiency as the dependent variable and mechanical power, thigh and leg co-contraction, stride rate and age as independent variables. It was possible to explain up to 77% of the age-related variance in net VO2 and 62% of the variation in efficiency using combinations of these variables. Age was the best single predictor of both VO2 and efficiency. Co-contraction, possibly used to enhance joint stability, was an important component of the observed age-related differences, although mechanical power was not. Additional variance might be explained as specific growth-related factors affecting the metabolic cost of locomotion are identified, as mechanical work models improve, and as methods are developed to measure the effects of stored elastic energy and the metabolic cost of isometric muscle actions.  相似文献   

15.
人体机械功计算方法的实验研究   总被引：1，自引：1，他引：0  
人体运动中的机械功是评定运动效果的一个重要指标,由于人体生物结构的复杂性和器官功能的多重性特点,目前还没有形成公认的分析计算方法。本研究首先在作者提出的假设之下给出四类人体机械功计算的可能方法。采用Monark864型自行车功率定负荷,JagerEOS型心肺功能测试仪测室生理能耗,用环节分析法计算机械功。14名受试都是职业自行车队队员。本研究结果提示:采用刚体力学模型计算的人体机械功可看作是运动中生理能耗的一次近似,要提高计算准确度,还需考虑其它耗能因素,建立更为精细的人体能量代谢模型。  相似文献   

16.
In this study, a new system for the calibration of bicycle ergometers, home trainers and bicycle power monitoring devices is described. This system contains a portable calibration rig as well as a specialised calibration software and is designed for easy and efficient use directly on-site by non-expert personnel. Key features of the calibration rig include a cradle used to implement a torque reaction measurement technique, roller casters, sliding coupling, and crowned splines to facilitate and speed up the calibration process. The maximum power uncertainty delivered by the calibration rig for a nominal power level range of 50–600 W is ±0.9%. A software to guide users through the calibration process and generate calibration charts is described. To illustrate how the calibration system is typically used, the calibration charts of two different brands of home trainers have been obtained, and the power output measurement accuracy of two bicycle power monitoring devices has been determined. Power discrepancies were noted. The results in this study reveal that the calibration system is an effective tool in characterising the behaviour of home trainers.  相似文献   

17.
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.  相似文献   

18.
Sprint push-off technique is fundamental to sprint performance and joint stiffness has been identified as a performance-related variable during dynamic movements. However, joint stiffness for the push-off and its relationship with performance (times and velocities) has not been reported. The aim of this study was to quantify and explain lower limb net joint moments and mechanical powers, and ankle stiffness during the first stance phase of the push-off. One elite sprinter performed 10 maximal sprint starts. An automatic motion analysis system (CODA, 200 Hz) with synchronized force plates (Kistler, 1000 Hz) collected kinematic profiles at the hip, knee, and ankle and ground reaction forces, providing input for inverse dynamics analyses. The lower-limb joints predominately extended and revealed a proximal-to-distal sequential pattern of maximal extensor angular velocity and positive power production. Pearson correlations revealed relationships (P < 0.05) between ankle stiffness (5.93 ± 0.75 N x m x deg(-1)) and selected performance variables. Relationships between negative power phase ankle stiffness and horizontal (r = -0.79) and vertical (r = 0.74) centre of mass velocities were opposite in direction to the positive power phase ankle stiffness (horizontal: r = 0.85; vertical: r = -0.54). Thus ankle stiffness may affect the goals of the sprint push-off in different ways, depending on the phase of stance considered.  相似文献   

19.
The purpose of the authors in this study was to develop an instrument to assess fourth and fifth grade students' attitudes toward physical education. The methods for validation included (a) an elicitation study and instrument question development, (b) a pilot study, and (c) a series of analyses to assess, construct, and content validity and to assess reliability. Once data for 1,344 students were collected, an iterative process was completed using principal component analysis, exploratory factor analysis, Cronbach's alpha, and confirmatory factor analysis using structure equation modeling. Data analysis showed that the instrument fit two different models. The first model shows students' attitudes to be influenced by cognition and affect. The second model shows a 4-factor model comprised of cognition- teacher, cognition-curriculum, affect- teacher, and affect-curriculum. This study yielded an instrument with valid and reliable scores that can assess elementary school students' attitudes toward physical education.  相似文献   

20.
Evaluations were made of the stability reliability of force measurements obtained from an Ariel dynamometer, the test -- retest reliability of force and power data for bench presses using the same dynamometer at multiple velocities, and the logical (face) validity of force and power output using the same instrument and exercise. Stability reliability of the dynamometer was determined from daily duplicate force calibration checks using two standard loads. Intra- and intertest coefficients of variation ranged from 0.07% to 1.16%. The test -- retest reliability of the bench press force and power outputs of 33 young men as well as the logical validity of their bench press force and power outputs were assessed at 0.0, 0.124, 0.496, and 0.868 m · sec-1, respectively. Intraclass correlation coefficients for force and power ranged from .95 to .99. Plots for both force and power were similar to those expected for analogous single-joint exercises. Therefore, data presented here support the stability reliability of the dynamometer for force measurements, the reliability of the bench press protocol, and the face validity of force outputs over a velocity spectrum.  相似文献   

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