中等强度有氧运动改善运动中心血管风险的研究

摘要：目的：旨在观察3个月50%~60%VO2max强度有氧运动对50~59岁人群运动中心血管风险的影响,为该人群安全有效健身方案提供科学指导。方法：问卷调查入选的50~59岁受试者通过在Bruce递增负荷实验中持续出现心电血压异常指征终止实验和一过性心电血压异常,入选66例受试者并将其分为正常组（C组）、持续异常组（Y组）及一过性异常组（YH组）,实施三个月的50%~60%VO2max强度每周300 min的规律跑步运动,干预前后测定人体测量学、生理生化、超声检查和递增负荷实验中相关指标,并评估变化。结果：3个月干预后Y组男性和女性的心电血压异常发生率降低至69.2%和58.3%,YH组男性和女性心电血压异常发生率降低至25%和75%。同时研究发现,干预后Y组及YH组受试者运动后心肌酶水平均显著下降,完成的运动负荷显著提高,心血管机能、形态学指标、血脂及自主神经功能显著改善。结论：50~59岁人群递增负荷运动中可出现心血管风险,为期3个月的50%~60%VO2max强度跑步运动可降低风险者其运动中心血管风险,提高安全运动上限。     

具有取大取小合成算子的模糊关系几何规划

本文讨论具有取大取小合成算子的模糊关系几何规划,首先介绍模糊关系几何规划的可行域的结构,再讨论具有取大取小合成算子的模糊关系几何规划的最优解的特征,然后提出求解模糊关系几何规划极大法,最后给出数值例子。     

Critical power derived from a 3-min all-out test predicts 16.1-km road time-trial performance

Abstract

It has been shown that the critical power (CP) in cycling estimated using a novel 3-min all-out protocol is reliable and closely matches the CP derived from conventional procedures. The purpose of this study was to assess the predictive validity of the all-out test CP estimate. We hypothesised that the all-out test CP would be significantly correlated with 16.1-km road time-trial (TT) performance and more strongly correlated with performance than the gas exchange threshold (GET), respiratory compensation point (RCP) and V?O₂ max. Ten club-level male cyclists (mean±SD: age 33.8±8.2 y, body mass 73.8±4.3 kg, V?O₂ max 60±4 ml·kg^?1·min^?1) performed a 10-mile road TT, a ramp incremental test to exhaustion, and two 3-min all-out tests, the first of which served as familiarisation. The 16.1-km TT performance (27.1±1.2 min) was significantly correlated with the CP (309±34 W; r=?0.83, P<0.01) and total work done during the all-out test (70.9±6.5 kJ; r=?0.86, P<0.01), the ramp incremental test peak power (433±30 W; r=?0.75, P<0.05) and the RCP (315±29 W; r=?0.68, P<0.05), but not with GET (151±32 W; r=?0.21) or the V?O₂ max (4.41±0.25 L·min^?1; r=?0.60). These data provide evidence for the predictive validity and practical performance relevance of the 3-min all-out test. The 3-min all-out test CP may represent a useful addition to the battery of tests employed by applied sport physiologists or coaches to track fitness and predict performance in atheletes.     

The relationship between critical power and running performance

Critical power is a theoretical concept that presumes there is a certain work‐rate which may be maintained without exhaustion. The extent to which critical power predicts running performance over varying distances has not been determined, and so the aim of this study was to correlate measurements of critical power in the laboratory to running performances in the field at 40 m and 1, 10 and 21.1 km in a group of 17 male longdistance runners (mean ± s.d. age = 31.7 ± 7.3 years). Each subject ran to exhaustion on the treadmill in the laboratory at six different speeds, ranging from 17 to 25 km h^‐1. Least squares analyses were used to fit an exponential decay to the relationship between the running speed (y) versus time to exhaustion (x). Critical power was calculated as the running speed (y) coinciding with the asymptote or C parameter of the y = A‐e^(‐Bx) + C relationship. The VO₂ max was also measured in all subjects. For the data in the field, each subject was timed over 40 m and 1 km and participated in 10‐ and 21.1‐km races. The mean critical power of die subjects in this study was 18.5 ± 1.6 km h^‐1. The test‐retest correlation coefficient for the determination of critical power was r = 0.99. The mean VO₂ max, measured in a progressive exercise protocol starting at 13 km h^‐1 and increasing by 1 km h^‐1 every minute, was 59.2 ± 4.6 ml O₂ kg^‐1 min^‐1. The 40‐m times ranged from 5.57 to 6.95 s, the 1‐km times from 2:46 to 3:55 min:s, the 10‐km times from 30:43 to 42:02 min:s and the 21‐km times from 67:00 to 95:45 min:s. Critical power predicted running times over 1 km (r = ‐0.75, P< 0.001), 10 km (r = ‐ 0.85, P< 0.00001) and 21.1 km (r = ‐ 0.79, P< 0.001) in this heterogeneous group of runners. The correlation coefficients for VO₂ max and running performances were similar to the above at all distances. Even in the best relationship between critical power and the time taken to run 10 km, only 72% of the variation in the 10‐km running time could be accounted for by differences in critical power. While the test of critical power may be repeatable and correlate significantly with VO₂ max (r = 0.77, P< 0.001), the measurement lacks the degree of specificity required to predict running performance in trained subjects of varying ability.     

Training Responses of Speed Skaters during a Competitive Season

Abstract

The purpose of this study was to test the effects of a 10-month exercise program on bone mineral content (BMC) and bone mineral content/bone width (BMC/BW) of postmenopausal women. Thirty-one women (ages 57-83) completed either a general aerobics exercise program (n = 10), a general aerobics plus upper body weight training exercise program (n = 10), or served as nonexercising control subjects (n = 11). Average compliance rates for the exercise subjects ranged from 72 to 80%. All subjects were pre- and posttested for BMC and BMC/BW in the radius of the nondominant forearm. ANOVA results indicated that there were significant differences between the exercise and control subjects in the amount of change in BMC and in BMC/BW (p < .05) during the course of the study. The exercise subjects experienced mean increases of 1.38% and 1.33% in BMC and BMC/BW, respectively, whereas the control group had decreases of 2.50% and 258%. No significant differences were found for subjects in the two types of exercise programs, suggesting that the effects of exercise relative to maintenance of bone density may be general as well as localized.     

Pygmalion in the Gym: A Model for the Communication of Teacher Expectations in Physical Education

Abstract

Much research on teacher expectations has focused on ways in which teacher perceptions of student ability can ultimately affect student performance. The majority of this research has indicated that teacher expectations not only determine certain types of student performance, but also serve to sustain low and high levels of performance. Observational research has also demonstrated that differential teacher-student interactions are related to certain levels of teacher expectations. For example, it has been shown that high expectancy students receive more praise, acceptance of ideas, contact and wait time, and more response opportunities than low expectancy students. Much of this research has been generated from studies related to classroom instruction. Very little of this research, however, has been operational in the physical education setting. One reason for this is the absence of a model in physical education through which this type of research can be generated. This article presents such a model showing how expectations are formed, how they are communicated, and how they sustain low and high levels of student growth and performance. The model further illustrates the causal relationship among teacher expectations, dyadic interactions and student growth and performance. Suggestions for future research techniques to determine causal flow among variables are also presented.     

Physiologic Effects of Distance Running Training on Teenage Females1

Abstract

The purpose of this study was to investigate selected physiological changes that occurred with distance training in teenage females. Two groups of untrained teenage females were matched on [Vdot]O₂ max, percent utilization of [Vdot]O ₂ @ 9.66 km/hr, peak heart rate, and percent body fat. One group served as control (n = 9) while the other (n =10) underwent a 20-week training program designed to gradually increase the subjects' average mileage from 0 to 32.2 km per week. At the end of the 20 weeks, a MANOVA revealed significant mean differences within the trained group and no significant mean differences within the control group. The univariate analysis revealed that significant (p <0.05) mean differences found within the training group were for [Vdot]O ₂ max (45.1 vs. 49.3 ml · kg ^–1 · min ^–1 ), percent utilization of [Vdot]O ₂ @9.66 km/hr (76.5% vs. 67.5%), and economy VO ₂ @9.66 km/hr (34.5vs.33.2 ml · kg ^–1 · min ^–1 ). Of the variables which exhibited significant training effects, percent utilization of [Vdot]O ₂ max showed the greatest relative change, a 12.2% decrease, with [Vdot]O ₂ max showing a 9.3% increase. The posttest results were similar to the research literature for training effects found for males and other age groups.     

有氧代谢能力与耐力项目训练中运动强度的选择

全面阐述了有氧代谢能力的概念，提出了最大摄氧量、无氧阈、最大摄氧量平台的持续时间都应是耐力训练的目标。在此基础上讨论了发展此3项目标应采用的训练强度。     

中老年人有氧及无氧工作能力的非实验室联合测定

本研究得出一种适合中老年人非实验室联合测定最大摄氧量和无氧功率的简便方法,使这两个反映有氧、无氧工作能力的指标达到实际应用推广阶段。     

心率监控在曲棍球运动中的应用

通过对备战2008年北京奥运会国家男子曲棍球运动员集训期间心率进行监测,探讨心率监测在运动训练过程中的特殊优势,分析曲棍球训练或测试过程中最大摄氧量测试、YO-YO测试、间歇跑测试心率的变化,探讨如何使用心率监控图来指导正确的运动训练。最后通过心率监控图观察最大摄氧量测试、YO-YO测试、间歇跑测试的心率变化特点。