The effects of work – rest duration on intermittent exercise and subsequent performance     

Mike Price  Karl Halabi 《Journal of sports sciences》2013,31(8):835-842

This study examined the effects of different work?–?rest durations during 40?min intermittent treadmill exercise and subsequent running performance. Eight males (mean?±?s: age 24.3?±?2.0 years, body mass 79.4?±?7.0?kg, height 1.77?±?0.05?m) undertook intermittent exercise involving repeated sprints at 120% of the speed at which maximal oxygen uptake (v-[Vdot]O_2max) was attained with passive recovery between each one. The work?–?rest ratio was constant at 1:1.5 with trials involving short (6:9?s), medium (12:18?s) or long (24:36?s) work?–?rest durations. Each trial was followed by a performance run to volitional exhaustion at 150% v-[Vdot]O_2max. After 40?min, mean exercise intensity was greater during the long (68.4?±?9.3%) than the short work?–?rest trial (54.9?±?8.1% [Vdot]O_2max; P?<?0.05). Blood lactate concentration at 10?min was higher in the long and medium than in the short work?–?rest trial (6.1?±?0.8, 5.2?±?0.9, 4.5?±?1.3?mmol?·?l^?1, respectively; P?<?0.05). The respiratory exchange ratio was consistently higher during the long than during the medium and short work?–?rest trials (P <?0.05). Plasma glucose concentration was higher in the long and medium than in the short work?–?rest trial after 40?min of exercise (5.6?±?0.1, 6.6?±?0.2 and 5.3?±?0.5?mmol?·?l^?1, respectively; P?<?0.05). No differences were observed between trials for performance time (72.7?±?14.9, 63.2?±?13.2, 57.6?±?13.5?s for the short, medium and long work?–?rest trial, respectively; P = 0.17), although a relationship between performance time and 40?min plasma glucose was observed (P?<?0.05). The results show that 40?min of intermittent exercise involving long and medium work?–?rest durations elicits greater physiological strain and carbohydrate utilization than the same amount of intermittent exercise undertaken with a short work?–?rest duration.  相似文献   

Moderate-domain pulmonary oxygen uptake kinetics and endurance running performance     

A. E. Kilding  E. M. Winter  M. Fysh 《Journal of sports sciences》2013,31(9):1013-1022

Abstract

The aims of this study were to determine if the primary time constant (τ) for oxygen uptake ([Vdot]O₂) at the onset of moderate-intensity treadmill exercise is related to endurance running performance, and to establish if τ could be considered a determinant of endurance running performance. Thirty-six endurance trained male runners performed a series of laboratory tests, on separate days, to determine maximal oxygen uptake ([Vdot]O_2max), the ventilatory threshold (V_T) and running economy. In addition, runners completed six transitions from walking (4 km · h^?1) to moderate-intensity running (80% V_T) for the determination of the [Vdot]O₂ primary time constant and mean response time. During all tests, pulmonary gas-exchange was measured breath-by-breath. Endurance running performance was determined using a treadmill 5-km time-trial, after which runners were considered as combined performers (n=36) and, using a ranking system, high performers (n=10) and low performers (n=10). Relationships between τ and endurance running performance were quantified using correlation coefficients (r). Stepwise multiple regression was used to determine the primary predictor variables of endurance running performance in combined performers. Moderate correlations were observed between τ, mean response time and endurance running performance, but only for the combined performers (r=?0.55, P=0.001 and r=?0.50, P=0.002, respectively). The regression model for predicting 5-km performance did not include τ or mean response time. The velocity at [Vdot]O_2max was strongly correlated to endurance running performance in all groups (r=0.72 – 0.84, P < 0.01) and contributed substantially to the prediction of performance. In conclusion, the results suggest that despite their role in determining the oxygen deficit and having a moderate relationship with endurance running performance, neither τ nor mean response time is a primary determinant of endurance running performance.  相似文献   

氧气呼吸器供氧系统分析与探讨     

冯华瑞  乔宁 《大众科技》2013,(3):80-81

介绍氧气呼吸器的供氧原理及使用要点,对自动供氧系统进行分析探讨,提出相关建议。  相似文献   

肌酸补充和电刺激对C2C12肌管糖摄入的效应及机制研究     

赵秀峰  徐晓阳  闫旭洁 《北京体育大学学报》2013,36(2):48-54

目的:旨在研究肌酸补充(CS)和电刺激(ES)对C2C12肌管葡萄糖摄取相关通路蛋白含量和基因表达的影响,阐明肌酸对GLUT4调节的相关信号通路,并讨论CS是否对ES具有叠加效应,为肌酸提高耐力水平提供新的理论依据。研究方法:0.5mM和2 mM浓度的肌酸孵育分化5 d的肌管48h,然后电刺激(15V,30ms,3Hz)共分化7d的肌管120 min。结果:ES引起AMPK-α2和GLUT4 mRNA表达及GLUT4蛋白含量显著增加(P<0.05),糖原显著下降(P<0.05)。不同浓度的CS没有引起AMPK-α2 mRNA表达变化,却使得GLUT4 mRNA和蛋白含量显著增加(P<0.05),糖原含量也无显著性增加(P>0.05)。ES+CS组与C组和同浓度CS组相比,明显上调AMPK-α2 mRNA和GLUT4 mRNA表达及GLUT4蛋白含量(P<0.05)。结论:1)15V,30ms,3Hz的刺激参数,ES120min没有引起细胞膜明显损伤,是研究耐力运动对肌肉糖代谢影响的适合参数。2)ES能通过AMPK途径增加肌管糖摄入和糖转运。3)单纯CS对肌管糖含量没影响,肌酸或许是通过AMPK非依赖性通路调节糖摄入。4)CS对ES对糖摄入的调节具有叠加效应。  相似文献   

瑞士球核心稳定性训练对心肺及其调节功能影响的实验研究     

王艳霞  赵敬国 《吉林体育学院学报》2013,(2):87-90

观察为期四周瑞士球核心稳定性训练（球上跪姿抬臂）对普通女大学生心率变异性和最大吸氧量的影响规律。利用芬兰产的POLAR S810i遥测心率表及瑞典产的MONARK 839E有氧功率车为工具,测量比较了四周瑞士球核心稳定性训练前后18名普通女大学生（实验组10人,对照组8人）心率变异性指标、最大吸氧量以及血压、心率的变化。经过四周锻炼,实验组的10名受试者均能在瑞士球上维持跪姿抬臂标准姿势5min。实验组最大吸氧量绝对值呈现极显著性增加（P〈0.01）,相对值呈现显著性增加（P〈0.05）、舒张压、心率则出现了显著性降低（P〈0.05）;SD、RMSSD以及HF都出现了显著性增加（P〈0.05）。对照组各项指标均未出现显著性差异（P〉0.05）。四周瑞士球核心稳定性训练可显著提高心肺功能,降低安静时交感神经的紧张性,增加副交感神经的紧张性。提示该训练方法对强身健体、缓解压力可能有显著性作用。  相似文献   

Enhanced expectancies improve movement efficiency in runners     

Isabelle Stoate  Rebecca Lewthwaite 《Journal of sports sciences》2013,31(8):815-823

Abstract

We followed up on recent findings demonstrating that enhancing performers' expectancies can improve their performance. Specifically, we examined whether providing experienced runners with positive feedback regarding their movement efficiency would increase running efficiency. Two groups of experienced runners ran on a treadmill at 75% of their maximum oxygen consumption ([Vdot]O_2max) for 10 min. One group (enhanced expectancy) was provided with (fabricated) feedback about the efficiency of their running style every 2 min. A control group was not given feedback. Oxygen consumption decreased in the enhanced expectancy group across measurement times (every 2 min for 10 min), but remained the same in the control group. In addition, performance perceptions changed only in the enhanced expectancy group, indicating a perception of greater ease of running and reduced fatigue when assessed after compared with before running. Finally, positive affect increased from a pre- to a post-test in the enhanced expectancy group, in contrast to the control group. Our findings show that enhanced expectancies can have a positive effect on movement efficiency and running experience. They add to the accumulating evidence for the social-cognitive-affective-motor nature of motor performance.  相似文献   

Recovery of pulmonary diffusing capacity after maximal exercise     

Jess Rasmussen  Birgitte Hanel  Kari Saunamaki  Niels H. Secher 《Journal of sports sciences》2013,31(6):525-531

Abstract

Pulmonary diffusing capacity (Dl_co), together with spirometric variables, arterial oxygen tension (paO₂) and cardiac output were determined before and at intervals after maximal arm cranking, treadmill running and erogmeter rowing. Independent of the type of exercise, Dl_co increased immediately post‐exercise from a median 13.6 (range 7.3–16.3) to 15.1 (9.3–19.6) mmol min^‐1 kPa^‐1 (P <0.01). However, it decreased to 11.6 (6.9–15.5) mmol min^‐1 kPa^‐1 (P <0.01) after 24 h with cardiac output and paO₂ at resting values, and Dl_co normalized after 20 h. Thoracic electrical impedance at 2.5 and 100 kHz increased slightly post‐exercise, indicating a decrease in thoracic fluid balance, and there were no echocardiographic signs of left ventricular failure at the time of the decrease in Dl_co. Also, active muscle (limb) circumference and volume, and an increase in haematocrit from 43.8 (38.0–47.0) to 47.1 (42.7–49.8) (P <0.01), had normalized at the time of the decrease in Dl_co. Vital capacity, forced vital capacity, forced expiratory volume in 1 s, peak and peak mid‐expiratory flows did not change. However, total lung capacity increased from 6.8 (5.0–7.6) to 7.0 (5.1–7.8) litres (P <0.05) immediately after exercise and remained elevated at 6.9 (5.1–8.7) litres (P <0.05) when a decrease in Dl_co was noted. The results demonstrate that independent of the type of maximal exercise, an approximate 15% reduction in Dl_co takes place 2–3 h post‐exercise, which normalizes during the following day of recovery.  相似文献   

Physiological Responses to Maximal Treadmill and Handweighted Exercise     

David Shaun Bryant  Fredric L. Goss PhD  Robert J. Robertson  Kenneth F. Metz  David S. Feingold 《Research quarterly for exercise and sport》2013,84(3):300-304

Abstract

The purpose of this investigation was to compare the peak physiological responses among four protocols that employed different amounts of handweighted exercise in 16 males (aged 26.3 ± 4.1 years). The four protocols were (a) uphill treadmill running (UR; 3.36 m-s¹, 2.5% grade increase-3 min¹); (b) uphill treadmill walking while pumping 1.36kg handweights (HW) (UWHW; 1.79ms¹, 5.0% grade increase-3 min¹; (c) treadmill walking while pumping .91-kg HW (WHW; 1.79 m-s¹, 0% grade, .91kg HW increase-3 min¹); and (d) standing in place and pumping HW (SHW; arm work as described in WHW). It was hypothesized that the peak responses would be inversely proportional to the estimated muscle mass activated (i.e., UR = UWHW > WHW > SHW). Dependent variables included peak oxygen uptake (VO₂ peak), peak heart rate (HRpeak), peak ventilation (V_epeak), and peak respiratory exchange ratio (RERpeak). No differences were noted between UR and UWHW with respect to any of the dependent variables. All variables (except RERpeak) were greater (p < .01) in UR and UWHW than either WHW or SHW. RERpeak was greater (p < .01) in UR and UWHW than in WHW. VO₂peak and HRpeak were greater (p < .01) in WHW when compared to SHW. Mean VO₂peak was 97.5, 69.7, and 60% of UR for UWHW, WHW, and SHW, respectively. Therefore, walking and pumping handweights provides a maximal stimulus to the oxygen transport system.  相似文献   

Validation of a single-stage submaximal treadmill walking test     

Lindsey Waddoups  Jennifer Fallon  Edward Heath 《Journal of sports sciences》2013,31(5):491-497

Abstract

The single-stage treadmill walking test of Ebbeling et al. is commonly used to predict maximal oxygen consumption ([Vdot]O_2max) from a submaximal effort between 50% and 70% of the participant's age-predicted maximum heart rate. The purpose of this study was to determine if this submaximal test correctly predicts [Vdot]O_2max at the low (50% of maximum heart rate) and high (70% of maximum heart rate) ends of the specified heart rate range for males and females aged 18 – 55 years. Each of the 34 participants completed one low-intensity and one high-intensity trial. The two trials resulted in significantly different estimates of [Vdot]O_2max (low-intensity trial: mean 40.5 ml · kg^?1 · min^?1, s = 9.3; high-intensity trial: 47.5 ml · kg^?1 · min^?1, s = 8.8; P < 0.01). A subset of 22 participants concluded their second trial with a [Vdot]O_2max test (mean 47.9 ml · kg^?1 · min^?1, s = 8.9). The low-intensity trial underestimated (mean difference = ?3.5 ml · kg^?1 · min^?1; 95% CI = ?6.4 to ?0.6 ml · kg^?1 · min^?1; P = 0.02) and the high-intensity trial overestimated (mean difference = 3.5 ml · kg^?1 · min^?1; 95% CI = 1.1 to 6.0 ml · kg^?1 · min^?1; P = 0.01) the measured [Vdot]O_2max. The predictive validity of Ebbeling and colleagues' single-stage submaximal treadmill walking test is diminished when performed at the extremes of the specified heart rate range.  相似文献   

Different types of compression clothing do not increase sub-maximal and maximal endurance performance in well-trained athletes     

Billy Sperlich  Matthias Haegele  Silvia Achtzehn  John Linville  Hans-Christer Holmberg  Joachim Mester 《Journal of sports sciences》2013,31(6):609-614

Abstract

Three textiles with increasing compressive surface were compared with non-compressive conventional clothing on physiological and perceptual variables during sub-maximal and maximal running. Fifteen well-trained endurance athletes (mean ± s: age 27.1 ± 4.8 years, [Vdot]O_2max 63.7 ± 4.9 ml · min^?1 · kg^?1) performed four sub-maximal (～70%[Vdot]O_2max) and maximal tests with and without different compression stockings, tights, and whole-body compression suits. Arterial lactate concentration, oxygen saturation and partial pressure, pH, oxygen uptake, and ratings of muscle soreness were recorded before, during, and after all tests. In addition, we assessed time to exhaustion. Sub-maximal (P = 0.22) and maximal oxygen uptake (P = 0.26), arterial lactate concentration (P = 0.16; 0.20), pH (P = 0.23; 0.46), oxygen saturation (P = 0.13; 0.26), and oxygen partial pressure (P = 0.09; 0.20) did not differ between the types of clothing (effect sizes = 0.00–0.45). Ratings of perceived exertion (P = 0.10; 0.15), muscle soreness (P = 0.09; 0.10) and time to exhaustion (P = 0.16) were also unaffected by the different clothing (effect sizes = 0.28–0.85). This was the first study to evaluate the effect on endurance performance of different types of compression clothing with increasing amounts of compressive surface. Overall, there were no performance benefits when using the compression garments.  相似文献