The effects of an increasing versus constant crank rate on peak physiological responses during incremental arm crank ergometry

We examined the effects of concomitant increases in crank rate and power output on incremental arm crank ergometry. Ten healthy males undertook three incremental upper body exercise tests to volitional exhaustion. The first test determined peak minute power. The subsequent tests involved arm cranking at an initial workload of 40% peak minute power with further increases of 10% peak minute power every 2 min. One involved a constant crank rate of 70 rev · min(-1), the other an initial crank rate of 50 rev · min(-1) increasing by 10 rev · min(-1) every 2 min. Fingertip capillary blood samples were analysed for blood lactate at rest and exhaustion. Local (working muscles) and cardiorespiratory ratings of perceived exertion (RPE) were recorded at the end of each exercise stage. Heart rate and expired gas were monitored continuously. No differences were observed in peak physiological responses or peak minute power achieved during either protocol. Blood lactate concentration tended to be greater for the constant crank rate protocol (P = 0.06). Test duration was shorter for the increasing than for the constant crank rate protocol. The relationship between local RPE and heart rate differed between tests. The results of this study show that increasing cadence during incremental arm crank ergometry provides a valid assessment of peak responses over a shorter duration but alters the heart rate-local RPE relationship.     

Effect of shoulder angle on physiological responses during incremental peak arm crank ergometry

This study examined the effect of shoulder angle and gender on physiological and perceptual responses during incremental peak arm ergometry. Healthy adults (nine males, seven females) volunteered for the study and completed an incremental arm ergometry test on two separate occasions at two different shoulder angles (90 degrees and 45 degrees). Initial work rate was set at 16 W x min-1 and was increased progressively until exhaustion. Cardiorespiratory and perceptual responses were recorded at the end of each minute and compared using separate three-way (position x work rate x gender) repeated-measures analyses of variance. The systematic bias of peak responses was examined using separate two-way (position x gender) analyses of variance, while reproducibility of these parameters was explored using intraclass correlation coefficients, measurement bias/ratio, and 95% ratio limits of agreement. Despite a significantly greater peak heart rate for the 45 degrees position, cardiorespiratory and perceptual responses were similar at peak exercise for both positions. Peak values for all variables, although similar, demonstrated similar and large inter-test variability for men and women. Reduction of the shoulder joint angle to 45 degrees did not enhance peak work rate and peak oxygen consumption during seated upper body exercise. Due to the large inter-test variability, arm ergometry should be conducted using the same seated position.     

The effect of crank rate strategy on peak aerobic power and peak physiological responses during arm crank ergometry

The main aim of this study was to determine whether the use of an imposed or freely chosen crank rate would influence submaximal and peak physiological responses during arm crank ergometry. Fifteen physically active men participated in the study. Their mean age, height, and body mass were 25.9 (s = 6.2) years, 1.80 (s = 0.10) m, and 78.4 (s = 6.1) kg, respectively. The participants performed two incremental peak oxygen consumption (VO(2peak)) tests using an electronically braked ergometer. One test was performed using an imposed crank rate of 80 rev x min(-1), whereas in the other the participants used spontaneously chosen crank rates. The order in which the tests were performed was randomized, and they were separated by at least 2 days. Respiratory data were collected using an on-line gas analysis system, and fingertip capillary blood samples ( approximately 20 microl) were collected for the determination of blood lactate concentration. Heart rate was also recorded throughout the tests. Time to exhaustion was measured and peak aerobic power calculated. Submaximal data were analysed using separate two-way repeated-measures analyses of variance, while differences in peak values were analysed using separate paired t-tests. Variations in spontaneously chosen crank rate were assessed using a one-way analysis of variance with repeated measures. Agreement between the crank rate strategies for the assessment of peak values was examined by calculating intra-class correlation coefficients (ICC) and 95% limits of agreement (95% LoA). While considerable between-participant variations in spontaneously chosen crank rate were observed, the mean value was not different (P > 0.05) from the imposed crank rate of 80 rev x min(-1) at any point. No differences (P > 0.05) were observed for submaximal data between crank strategies. Furthermore, mean peak minute power [158 (s = 20) vs. 158 (s = 18) W], time to exhaustion [739 (s = 118) vs. 727 (s = 111) s], and VO(2peak)[3.09 (s = 0.38) vs. 3.04 (s = 0.34) l x min(-1)] were similar for the imposed and spontaneously chosen crank rates, respectively. However, the agreement for the assessment of VO(2peak) (ICC = 0.78; 95% LoA = 0.04 +/- 0.50 l x min(-1)) between the cranking strategies was considered unacceptable. Our results suggest that either an imposed or spontaneously chosen crank rate strategy can be used to examine physiological responses during arm crank ergometry, although it is recommended that the two crank strategies should not be used interchangeably.     

The influence of crank rate on peak oxygen consumption during arm crank ergometry

The aim of this study was to assess the influence of three imposed crank rates on the attainment of peak oxygen consumption ( V O 2peak ) and other physiological responses during incremental arm crank ergometry. Twenty physically active, although non-specifically trained, males volunteered for the study. They completed an exercise protocol using an electrically braked arm ergometer (Lode Angio, Groningen, Netherlands) at crank rates of 60, 70 and 80 rev·min -1 . The order of tests was randomized and they were separated by at least 2 days. Peak V O 2 was significantly higher ( P ? 0.05) at 70 and 80 rev·min -1 than at 60 rev·min -1 . Peak ventilation volume increased as a function of crank rate and was higher ( P ? 0.05) at 80 than at 60 rev·min -1 . Peak heart rate was higher ( P ? 0.05) at 70 and 80 rev·min -1 than at 60 rev·min -1 . Furthermore, 70 and 80 rev·min -1 resulted in an extended test time compared with 60 rev·min -1 . The greater physiological responses observed during the tests at the two faster crank rates might have been the result of a postponement of acute localized neuromuscular fatigue, allowing for more work to be completed. We recommend, therefore, that an imposed crank rate between 70 and 80 rev·min -1 should be used to elicit V O 2peak and other physiological responses in arm crank ergometry.     

The influence of crank rate on peak oxygen consumption during arm crank ergometry

The aim of this study was to assess the influence of three imposed crank rates on the attainment of peak oxygen consumption (VO2peak) and other physiological responses during incremental arm crank ergometry. Twenty physically active, although non-specifically trained, males volunteered for the study. They completed an exercise protocol using an electrically braked arm ergometer (Lode Angio, Groningen, Netherlands) at crank rates of 60, 70 and 80 rev x min(-1). The order of tests was randomized and they were separated by at least 2 days. Peak VO2 was significantly higher (P < 0.05) at 70 and 80 rev x min(-1) than at 60 rev x min(-1). Peak ventilation volume increased as a function of crank rate and was higher (P < 0.05) at 80 than at 60 rev x min(-1). Peak heart rate was higher (P < 0.05) at 70 and 80 rev x min(-1) than at 60 rev x min(-1). Furthermore, 70 and 80 rev x min(-1) resulted in an extended test time compared with 60 rev x min(-1). The greater physiological responses observed during the tests at the two faster crank rates might have been the result of a postponement of acute localized neuromuscular fatigue, allowing for more work to be completed. We recommend, therefore, that an imposed crank rate between 70 and 80 rev x min(-1) should be used to elicit VO2peak and other physiological responses in arm crank ergometry.     

The effect of pedal crank arm length on joint angle and power production in upright cycle ergometry

The aim of this study was to determine the effect of five pedal crank arm lengths (110, 145, 180, 230 and 265 mm) on hip, knee and ankle angles and on the peak, mean and minimum power production of 11 males (26.6 +/- 3.8 years, 179 +/- 8 cm, 79.6 +/- 9.5 kg) during upright cycle ergometry. Computerized 30 s Wingate power tests were performed on a free weight Monark cycle ergometer against a resistance of 8.5% body weight. Joint angles were determined, with an Ariel Performance Analysis System, from videotape recorded at 100 Hz. Repeated-measures analysis of variance and contrast comparisons revealed that, with increasing crank arm lengths, there was a significant decrement in the minimum hip and knee angles, a significant increment in the ranges of motion of the joints, and a parabolic curve to describe power production. The largest peak and mean powers occurred with a crank arm length of 180 mm. We conclude that 35 mm changes in pedal crank arm length significantly alter both hip and knee joint angles and thus affect cycling performance.     

The effect of pedal crank arm length on joint angle and power production in upright cycle ergometry

The aim of this study was to determine the effect of five pedal crank arm lengths (110, 145, 180, 230 and 265 mm) on hip, knee and ankle angles and on the peak, mean and minimum power production of 11 males (26.6+/-3.8 years, 179+/-8 cm, 79.6+/-9.5 kg) during upright cycle ergometry. Computerized 30 s Wingate power tests were performed on a free weight Monark cycle ergometer against a resistance of 8.5% body weight. Joint angles were determined, with an Ariel Performance Analysis System, from videotape recorded at 100 Hz. Repeated-measures analysis of variance and contrast comparisons revealed that, with increasing crank arm lengths, there was a significant decrement in the minimum hip and knee angles, a significant increment in the ranges of motion of the joints, and a parabolic curve to describe power production. The largest peak and mean powers occurred with a crank arm length of 180 mm. We conclude that 35 mm changes in pedal crank arm length significantly alter both hip and knee joint angles and thus affect cycling performance.     

The effects of arm crank strategy on physiological responses and mechanical efficiency during submaximal exercise

The purpose of this study was to compare submaximal physiological responses and indices of mechanical efficiency between asynchronous and synchronous arm ergometry. Thirteen wheelchair-dependent trained athletes performed eight steady-state incremental bouts of exercise (0 to 140 W), each lasting 4 min, using synchronous and asynchronous arm-cranking strategies. Physiological measures included oxygen uptake (VO2), heart rate, and blood lactate concentration. The power outputs corresponding to fixed whole blood lactate concentrations of 2.0 to 4.0 mmol x l(-1) were calculated using linear interpolation. Mechanical efficiency indices - gross efficiency, net efficiency, and work efficiency - were also calculated. An analysis of variance with repeated measures was applied to determine the effect of crank mode on the physiological parameters. Oxygen uptake was on average 10% lower (P < 0.01), and both net efficiency (P < 0.01) and gross efficiency (P < 0.01) were higher, during the asynchronous strategy at both 60 and 80 W (gross efficiency: 16.9 +/- 2.0% vs. 14.7 +/- 2.4% and 17.5 +/- 1.8% vs. 15.9 +/- 2.6% at 60 and 80 W respectively). There were no differences in heart rate, blood lactate concentration or power output at either of the blood lactate reference points between the asynchronous and synchronous strategies (P > 0.05). In conclusion, test specificity is an important consideration. If a synchronous strategy is to be adopted, it is likely to result in lower efficiency than an asynchronous strategy. The exercise testing scenario may help dictate which method is ultimately chosen.     

身体姿势和形体练习文献综述

在近十年文献资料的基础上 ,综述了身体姿势的测量方法 ,部分异常姿势的检出率、生理机制和形体练习的内容等已有的研究成果。为促进青少年拥有正确的身体姿势和优美的形体 ,作更进一步研究提供一定的依据和线索。     

健身运动对青春期女孩身体成分发育的影响

通过测量肱三头肌位和肩胛下角位皮褶厚度,分析身体组成,探讨健身运动对青春期女孩发育的影响.结果发现皮褶厚度随年龄的增长而增加;健身组皮褶厚度及体脂%均低于安静组,且皮褶厚度在12～16岁具显著性差异;安静组体重的增加较多地来自皮下脂肪的增长,而健身组较多地来自去脂体重的增加.提示,女孩皮下脂肪在青春期持续迅速积累,健身运动可使体脂肪含量降低,骨骼、肌肉等去脂体重成分增长,健身运动对12～16岁间女孩对皮下脂肪发育的影响较明显.     

体操运动的起源及健身功能研究

从体操的起源谈起,从体操的健身功能扩展,通过竞技体操和大众健美操对比说明基础普及和提高的哲学关系,着重指出体操在发展中必须注意健身功能的开发,才能保证体操运动的健康发展.     

体育运动对免疫系统及上呼吸道影响的研究

激烈运动及较高的心理压力会抑制运动员体内的免疫系统；相反，适度的有氧运动则有提高运动员体内免疫功能的效果。保持适当的运动量，养成良好的卫生习惯，避免接触传染，对运动员的健康维护与体质的增强都将有所裨益。     

补充丙酮酸肌酸、肌酸和肉碱对运动员身体成分及运动能力的影响

目的:观察运动员在系统训练过程中服用丙酮酸肌酸、肌酸和肉碱时身体成分及运动能力的不同影响.方法:36名国家青年篮球队退动员,随机分为安慰剂组、丙酮酸肌酸组、肌酸组和肉碱组.正常训练同时持续6周服用营养补剂和安慰剂,实验前、后进行身体成分测试和运动能力测试.结果:在系统训练中使用丙酮酸肌酸可以明显减少运动员的脂肪,降低体脂百分数;能够明显增加运动员肌肉重量和去脂体重;明显提高运动员运动能力.男运动员在系统训练中使用肌酸和丙酮酸肌酸,可以减少身体脂肪,但使用丙酮酸肌酸减少脂肪的幅度更大;同时,使用丙酮酸肌酸还能够明显增加肌肉重量;在系统训练中使用丙酮酸肌酸比肌酸更能提高运动能力且没有副反应.女运动员在训练中使用肉碱和丙酮酸肌酸均能减少身体脂肪、提高运动能力,丙酮酸肌酸的效果更明显.结论:在系统训练中使用丙酮酸肌酸比肌酸和肉碱更能减少运动员身体脂肪、增加肌肉重量,提高运动能力.     

Acute effects of small changes in crank length on gross efficiency and pedalling technique during submaximal cycling

ABSTRACT

The main purpose of this study was to assess the acute effects of small changes in crank length (assumable by competitive cyclists) on metabolic cost and pedalling technique during submaximal cycling. Twelve amateur road cyclists performed three sets of submaximal pedalling (150, 200 and 250 W) at a constant cadence (91.3 ± 0.8 rpm) in a randomised order with three commonly used crank lengths, preferred (172.5–175 mm), +5 mm and ?5 mm. Energy cost of pedalling, kinetic and kinematic variables were simultaneously registered. Changes in crank length had no significant effect on heart rate (144 ± 13, 145 ± 12 and 145 ± 13 bpm, respectively) and gross efficiency (GE) (20.4 ± 2.1, 20.1 ± 2.2 and 20.3 ± 2.4%, respectively). A longer crank induced a significant (P < 0.05) reduction of positive impulse proportion (PIP) (0.9–1.9%) due to a greater maximum (1.0–2.3 N · m) and minimum torque (1.0–2.2 N · m). At the same time, the maximum flexion and range of motion of the hip and knee joints were significantly increased (1.8–3.4° and P < 0.05), whereas the ankle joint was not affected. In conclusion, the biomechanical changes due to a longer crank did not alter the metabolic cost of pedalling, although they could have long-term adverse effects. Therefore, in case of doubt between two lengths, the shorter one might be recommended.     

The acute effects of bodyweight suspension exercise on muscle activation and muscular fatigue

This investigation examined effects of two exercise modes (barbell, BB; bodyweight suspension, BWS) on muscle activation, resistance load, and fatigue. During session one, nine resistance-trained males completed an elbow flexion one-repetition maximum (1RM). During sessions two and three, subjects completed standing biceps curls to fatigue at 70% 1RM utilizing a randomized exercise mode. Surface electromyography (sEMG) recorded muscle activation of the biceps brachii, triceps brachii, anterior deltoid, posterior deltoid, rectus abdominis, and erector spinae. BWS resistance load was measured using a force transducer. Standing maximal voluntary isometric contractions of the elbow flexors recorded at 90° were used to determine the isometric force decrement and rate of fatigue (ROF) during exercise. sEMG and resistance load data were divided into 25% contraction duration bins throughout the concentric phase. BWS resulted in a 67.7?±?7.4% decline in resistance load throughout the concentric phase (p?≤?0.05). As a result, BB elicited higher mean resistance loads (31.4?±?4.0?kg) and biceps brachii sEMG (84.7?±?27.8% maximal voluntary isometric contractions, MVIC) compared with BWS (20.4?±?3.4?kg, 63.4?±?21.6% MVIC). No difference in rectus abdominis or erector spinae sEMG was detected between exercise modes. Isometric force decrement was greater during BWS (?21.7?±?7.0?kg) compared with BB (?14.9?±?4.7?kg); however, BB (?3.0?±?0.8?kg/set) resulted in a steeper decline in ROF compared with BWS (?1.7?±?0.6?kg/set). The variable resistance loading and greater isometric force decrement observed suggest that select BWS exercises may resemble variable resistance exercise more than previously considered.     

序贯法和单纯进补法对慢性运动应激大鼠脑组织和胸腺组织糖皮质激素受体的影响

探讨慢性运动应激引起免疫抑制的发生机理和中药不同的调理方式对慢性应激下血清皮质酮、脑组织和胸腺组织糖皮质激素受体的影响。研究方法：SD雄性大鼠40只，随机平均分为4组，分别为对照组（C）、训练组（T）、服药1组（M1，先补脾，后补肾法，即序贯法）和服药2组（M2，补肾法），采用放免法观察8用递增负荷游泳和中药不同调理方式时不同组别皮质酮和糖皮质激素受体的影响。研究发现，训练组皮质酮显著性高于对照组（P〈0．05）；而M1组和M2组的皮质酮显著低于训练组（P〈0．05，P〈0．05）；与对照组相比较，训练组脑组织糖皮质激素受体含量显著性低于对照组（P〈0．01）；M1组和M2组均高于训练组，但无显著性差异（P〉0．05；P〉0．05）；与对照组相比较，训练组胸腺糖皮质激素受体作用位点，显著低于对照组（P〈0．01）；M1组与训练组相比，显著高于训练组（P〈0．01）；M2组高于训练组，但没有显著性差异（P〉0．05），而M1组高于M2组（P〈0．01）。研究结果提示，长期大运动量递增负荷训练可使血清皮质酮水平升高，脑组织GR含量下降，减弱了对糖皮质激素的敏感性，使HPA轴的反馈作用降低。长期大运动量递增负荷训练，可导致胸腺细胞上GR的结合位点明显降低，胸腺细胞上（承水平降低，直接影响免疫细胞的成熟，而降低机体的免疫能力，可能与长时间大强度运动训练会造成免疫抑制，易惠呼吸道感染有关。采用序贯法可提高胸腺细胞上GR数目有利于T细胞的成熟和分化，减少糖皮质激素对淋巴细胞的抑制作用，使机体的免疫功能得到改善和提高。     

有氧运动的健身价值研究进展

就有氧运动对健康的影响作了较全面的综述，讨论了有氧运动的健身意义及其对人体各方面机能影响机制的新的研究成果。     

杭州市体育健身娱乐市场供需结构研究

通过对杭州市经营性体育健身娱乐部门的调查 ,初步了解市民的体育消费意识、消费行为以及在现有服务体系内的供需结构特征 ,揭示了资金来源、投资方式、企业性质、服务质量、经营方式、总体发展规划、市场潜力、管理水平、法制建设等方面的不足和问题 ,提出了若干宏观发展策略。     

The effects of carbohydrate supplementation during repeated bouts of prolonged exercise on saliva flow rate and immunoglobulin A

The purpose of this study was to assess the effect of carbohydrate (CHO) feeding during different periods of two 90-min cycling bouts (the first bout began at 09:00?h and the second bout began at 13:30?h) at 60% maximal oxygen uptake ([Vdot]O_2max) on saliva flow rate and saliva immunoglobulin A (sIgA) responses to the second exercise bout. The study consisted of three investigations: carbohydrate supplementation during (1) the first hour of the recovery interval (CHO-REC), (2) during the first bout of exercise and (3) during the second bout of exercise. Each investigation included two trials completed in a counterbalanced order and separated by at least 4 days. Participants consumed a lemon-flavoured 10% w/v carbohydrate beverage or placebo (22?ml?·?kg^?1 body mass) in the first hour of the recovery interval (n = 8) and 500?ml just before exercise, followed by 250?ml every 20?min during exercise in the first (n = 9) and second exercise bouts (n = 9). Timed unstimulated saliva samples were collected at 10?min before exercise, after 48?–?50?min of exercise and during the last 2?min of exercise, at 1?h post exercise, 2?h post exercise (first exercise bout only), and 18?h post exercise (second exercise bout only). Venous blood samples were taken 5?min before exercise and immediately after exercise for both exercise bouts in all trials. The main findings of the present study were as follows. First, carbohydrate ingestion during both exercise bouts, but not during the recovery interval, better maintained plasma glucose concentrations and attenuated the increase in plasma adrenaline and cortisol concentrations after the second exercise bout compared with placebo. Second, carbohydrate feeding had no effect on saliva flow rate and sIgA secretion rate compared with placebo. Third, saliva flow rate and sIgA concentration returned to pre-exercise bout 1 values within 2?h in all trials. Fourth, there was no delayed effect of exercise on oral immunity. These findings suggest that carbohydrate ingestion during the first or second bout of exercise, but not during the recovery interval, is likely to better maintain plasma glucose concentrations and attenuate the responses of plasma stress hormones to a second exercise bout than ingestion of fluid alone. Two bouts of 90?min cycling at 60% [Vdot]O_2max on the same day appears to inhibit saliva flow rate during the second exercise bout but does not alter sIgA transcytosis. Our results show that carbohydrate ingestion during any period of two prolonged exercise bouts does not induce different effects on oral immunity compared with placebo.     

有氧运动对女大学生身体形态和体脂的影响

本文以温州大学经常参加有氧锻炼的100名女大学生为实验组,同一年龄段无锻炼基础的100名女大学生为对照组,研究不同锻炼方式对女大学生身体形态、体脂的影响。结果显示：经常参加有氧锻炼的女大学生,在身体形态上发生变化,胸围增大、腰臀比缩小;瘦体重增加,体重指数（BMI）和体脂%明显小于对照组。表明经常参加有氧锻炼,有助于改善女大学生的身体形态和体脂成分,塑造更加完美的身材。