以循环经济理念促进和谐社会建设     

魏澄荣  程春生 《三明学院学报》2006,23(3):261-265

循环经济所内具的和谐本质、和谐功能与构建和谐社会的内在要求具有高度的一致性。循环经济以人为本的发展观、可持续发展的经济观、人和自然及社会和谐统一的系统观、低消耗和少排放的生产观、综合利益一致性的效益观有利于构建社会主义和谐社会。  相似文献   

Sodium lactate infusion during a cycling time-trial does not increase lactate concentration or decrease performance     

《European Journal of Sport Science》2013,13(6):367-374

Abstract

The aim of this study was to determine whether an exogenous sodium lactate infusion increases blood lactate concentration and decreases performance during a 20-km time-trial. Highly trained male cyclists performed a 20-km time-trial with a saline (control) or sodium lactate infusion. Sodium lactate was infused at rates previously observed to raise blood lactate concentration by 2 mmol·l^?1 in trained individuals cycling at 65% of maximum oxygen uptake. Blood lactate concentration increased (P≤0.0001) during both the control and sodium lactate trials compared with rest, with peak values of 9.6 and 10.6 mmol·l^?1, respectively. The increase in sodium lactate over time was not significantly different from the control (P=0.34). Time to complete the time-trial and average power for the time-trial were not significantly different between the control (25.72±0.80 min; 348.0±32.4 W) and sodium lactate trials (25.58±0.93 min; 352.6±39.3 W). In addition, rating of perceived exertion, heart rate, and respiratory parameters did not differ between trials. In conclusion, when exogenous lactate is infused during a 20-km cycling time-trial, an exercise bout performed above the maximal lactate steady state, blood lactate concentration did not increase. Furthermore, exogenous lactate infusion did not decrease exercise performance, increase perceived exertion, or change respiratory parameters. Because lactate per se did not change performance outcomes or measured perceived exertion, we suggest that alternative objective measures of exercise intensity and performance be explored.  相似文献   

The effect of pre-exercise carbohydrate feedings on the intensity that elicits maximal fat oxidation     

Juul Achten & Asker E Jeukendrup 《Journal of sports sciences》2013,31(12):1017-1025

The aim of the present study was to examine the effect of ingesting 75?g of glucose 45?min before the start of a graded exercise test to exhaustion on the determination of the intensity that elicits maximal fat oxidation (Fat_max). Eleven moderately trained individuals ( V?O_2max: 58.9±1.0?ml?·?kg^?1?·?min^?1; mean±s_x¯ ), who had fasted overnight, performed two graded exercise tests to exhaustion, one 45?min after ingesting a placebo drink and one 45?min after ingesting 75?g of carbohydrate in the form of glucose. The tests started at 95?W and the workload was increased by 35?W every 3?min. Gas exchange measures and heart rate were recorded throughout exercise. Fat oxidation rates were calculated using stoichiometric equations. Blood samples were collected at rest and at the end of each stage of the test. Maximal fat oxidation rates decreased from 0.46±0.06 to 0.33±0.06?g?·?min^?1 when carbohydrate was ingested before the start of exercise (P?<0.01). There was also a decrease in the intensity which elicited maximal fat oxidation (60.1±1.9% vs 52.0±3.4% V?O_2max) after carbohydrate ingestion (P?<0.05). Maximal power output was higher in the carbohydrate than in the placebo trial (346±12 vs 332±12?W) (P?<0.05). In conclusion, the ingestion of 75?g of carbohydrate 45?min before the onset of exercise decreased Fat_max by 14%, while the maximal rate of fat oxidation decreased by 28%.  相似文献   

Effect of a novel pedal design on maximal power output and mechanical efficiency in well-trained cyclists     

Erwin Koninckx  Peter Hespel 《Journal of sports sciences》2013,31(10):1015-1023

Abstract

In this study, we evaluated the effects of a novel pedal design, characterized by a downward and forward shift of the cleat fixing platform relative to the pedal axle, on maximal power output and mechanical efficiency in 22 well-trained cyclists. Maximal power output was measured during a series of short (5-s) intermittent sprints on an isokinetic cycle ergometer at cadences from 40 to 120 rev · min^?1. Mechanical efficiency was evaluated during a submaximal incremental exercise test on a bicycle ergometer using continuous [Vdot]O₂ and [Vdot]CO₂ measurement. Similar tests with conventional pedals and the novel pedals, which were mounted on the individual racing bike of the participant, were randomized. Maximal power was greater with novel pedals than with conventional pedals (between 6.0%, s_x  = 1.5 at 40 rev · min^?1 and 1.8%, s_x  = 0.7 at 120 rev · min^?1; P = 0.01). Torque production between crank angles of 60° and 150° was higher with novel pedals than with conventional pedals (P = 0.004). The novel pedal design did not affect whole-body [Vdot]O₂ or [Vdot]CO₂. Mechanical efficiency was greater with novel pedals than with conventional pedals (27.2%, s_x  = 0.9 and 25.1%, s_x  = 0.9% respectively; P = 0.047; effect size = 0.9). In conclusion, the novel pedals can increase maximal power output and mechanical efficiency in well-trained cyclists.  相似文献   

Mechanical work and physiological responses to simulated cross country mountain bike racing     

Paul William Macdermid  Stephen Stannard 《Journal of sports sciences》2013,31(14):1491-1501

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Effect of suspension systems on the physiological and psychological responses to sub-maximal biking on simulated smoothand bumpy tracks     

John Titlestad  Tony Fairlie-Clarke  Mark Davie  Ian Watt  Stanley Grant 《Journal of sports sciences》2013,31(2):125-135

Abstract

The aim of this study was to compare the physiological and psychological responses of cyclists riding on a hard tail bicycle and on a full suspension bicycle. Twenty males participated in two series of tests. A test rig held the front axle of the bicycle steady while the rear wheel rotated against a heavy roller with bumps (or no bumps) on its surface. In the first series of tests, eight participants (age 19 – 27 years, body mass 65 – 82 kg) were tested on both the full suspension and hard tail bicycles with and without bumps fitted to the roller. The second series of test repeated the bump tests with a further six participants (age 22 – 31 years, body mass 74 – 94 kg) and also involved an investigation of familiarization effects with the final six participants (age 21 – 30 years, body mass 64 – 80 kg). Heart rate, oxygen consumption ([Vdot]O₂), rating of perceived exertion (RPE) and comfort were recorded during 10 min sub-maximal tests. Combined data for the bumps tests show that the full suspension bicycle was significantly different (P < 0.001) from the hard tail bicycle on all four measures. Oxygen consumption, heart rate and RPE were lower on average by 8.7 (s = 3.6) ml · kg^?1 · min^?1, 32.1 (s = 12.1) beats · min^?1 and 2.6 (s = 2.0) units, respectively. Comfort scores were higher (better) on average by 1.9 (s = 0.8) units. For the no bumps tests, the only statistically significant difference (P = 0.008) was in [Vdot]O₂, which was lower for the hard tail bicycle by 2.2 (s = 1.7) ml · kg^?1 · min^?1. The results indicate that the full suspension bicycle provides a physiological and psychological advantage over the hard tail bicycle during simulated sub-maximal exercise on bumps.  相似文献   

Quantification of spinning® bike performance during a standard 50-minute class     

M. A. Caria  F. Tangianu  A. Concu  A. Crisafulli  O. Mameli 《Journal of sports sciences》2013,31(4):421-429

Abstract

Spinning is a type of indoor fitness activity performed on stationary bikes by participants who pedal together to the rhythm of music and the motivating words of an instructor. Despite worldwide popularity of this type of recreational activity, to date there have been few, mainly non-scientific, studies of the impact of spinning on metabolic, respiratory, and cardiovascular functions. The main aim of this study was to evaluate a number of metabolic and cardiovascular variables during a standard 50-min class performed by Spinning® instructors of both sexes: six males (age 30 ± 4.8 years, body mass index 24 ± 2.5 kg · m^?2; mean ± s) and six females (age 34 ± 6.3 years, body mass index 21 ± 1.9 kg · m^?2). The mean power output, heart rate, and oxygen uptake during the performance were 120 ± 4 W, 136 ± 13 beats · min^?1, and 32.8 ± 5.4 ml · kg^?1 · min^?1 respectively for males, and 73 ± 43 W, 143 ± 25 beats · min^?1, and 30 ± 9.9 ml · kg^?1 · min^?1 respectively for females. Analysis of individual performances showed that they were compatible with physical exercise that ranged from moderate-to-heavy to very heavy, the latter conditions prevailing. The results show that this type of fitness activity has a high impact on cardiovascular function and suggest that it is not suitable for unfit or sedentary individuals, especially the middle aged or elderly, who are willing to begin a recreational physical activity programme.  相似文献   

Effects of Submaximal Exercise and Noise Exposure on Hearing Loss     

Helaine M. Alessio  Kathleen M. Hutchinson 《Research quarterly for exercise and sport》2013,84(4):413-419

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我国高水平女子短距离自行车运动员全程性多年训练不同阶段的专项训练手段及负荷特征   总被引：1，自引：0，他引：1  

江永华 《北京体育大学学报》2009,32(2)

近年来,我国女子短距离自行车运动员在世界大赛中获得了优异的成绩,系统的多年训练是她们成功的重要致因.运用文献资料法、访谈法、调查法、数理统计法以及逻辑分析法等方法,对我国部分高水平女子短距离自行车选手全程性多年训练实践中各阶段的专项训练手段及负荷进行了研究,力求揭示她们在各阶段训练中专项训练手段和负荷安排的一般性规律及某些个性特征,为科学地组织好运动员的多年训练,为我国女子短距离自行车竞技水平的持续发展提供理论依据与实践指导.  相似文献   

The validity and intra-tester reliability of markerless motion capture to analyse kinematics of the BMX Supercross gate start     

Josephine Grigg  Eric Haakonssen  Evelyne Rathbone  Robin Orr  Justin W. L. Keogh 《Sports biomechanics / International Society of Biomechanics in Sports》2018,17(3):383-401

The aim of this study was to quantify the validity and intra-tester reliability of a novel method of kinematic measurement. The measurement target was the joint angles of an athlete performing a BMX Supercross (SX) gate start action through the first 1.2 s of movement in situ on a BMX SX ramp using a standard gate start procedure. The method employed GoPro® Hero 4 Silver (GoPro Inc., USA) cameras capturing data at 120 fps 720 p on a ‘normal’ lens setting. Kinovea 0.8.15 (Kinovea.org, France) was used for analysis. Tracking data was exported and angles computed in Matlab (Mathworks®, USA). The gold standard 3D method for joint angle measurement could not safely be employed in this environment, so a rigid angle was used. Validity was measured to be within 2°. Intra-tester reliability was measured by the same tester performing the analysis twice with an average of 55 days between analyses. Intra-tester reliability was high, with an absolute error <6° and <9 frames (0.075 s) across all angles and time points for key positions, respectively. The methodology is valid within 2° and reliable within 6° for the calculation of joint angles in the first ~1.25 s.  相似文献