The multi-stage fitness test as a predictor of endurance fitness in wheelchair athletes     

Victoria L. Goosey-Tolfrey  Keith Tolfrey 《Journal of sports sciences》2013,31(5):511-517

Abstract

The aims of this study were two-fold: (1) to consider the criterion-related validity of the multi-stage fitness test (MSFT) by comparing the predicted maximal oxygen uptake ([Vdot]O_2max) and distance travelled with peak oxygen uptake ([Vdot]O_2peak) measured using a wheelchair ergometer (n = 24); and (2) to assess the reliability of the MSFT in a sub-sample of wheelchair athletes (n = 10) measured on two occasions. Twenty-four trained male wheelchair basketball players (mean age 29 years, s = 6) took part in the study. All participants performed a continuous incremental wheelchair ergometer test to volitional exhaustion to determine [Vdot]O_2peak, and the MSFT on an indoor wooden basketball court. Mean ergometer [Vdot]O_2peak was 2.66 litres · min^?1 (s = 0.49) and peak heart rate was 188 beats · min^?1 (s = 10). The group mean MSFT distance travelled was 2056 m (s = 272) and mean peak heart rate was 186 beats · min^?1 (s = 11). Low to moderate correlations (ρ = 0.39 to 0.58; 95% confidence interval [CI]: ?0.02 to 0.69 and 0.23 to 0.80) were found between distance travelled in the MSFT and different expressions of wheelchair ergometer [Vdot]O_2peak. There was a mean bias of ?1.9 beats · min^?1 (95% CI: ?5.9 to 2.0) and standard error of measurement of 6.6 beats · min^?1 (95% CI: 5.4 to 8.8) between the ergometer and MSFT peak heart rates. A similar comparison of ergometer and predicted MSFT [Vdot]O_2peak values revealed a large mean systematic bias of 15.3 ml · kg^?1 · min^?1 (95% CI: 13.2 to 17.4) and standard error of measurement of 3.5 ml · kg^?1 · min^?1 (95% CI: 2.8 to 4.6). Small standard errors of measurement for MSFT distance travelled (86 m; 95% CI: 59 to 157) and MSFT peak heart rate (2.4 beats · min^?1; 95% CI: 1.7 to 4.5) suggest that these variables can be measured reliably. The results suggest that the multi-stage fitness test provides reliable data with this population, but does not fully reflect the aerobic capacity of wheelchair athletes directly.  相似文献   

Optimization of insulin-mediated creatine retention during creatine feeding in humans     

G. Pittas  M. D. Hazell  E. J. Simpson  P. L. Greenhaff 《Journal of sports sciences》2013,31(1):67-74

Abstract

The aim of this study was to determine whether creatine ingested in combination with relatively small quantities of essential amino acids, simple sugars, and protein would stimulate insulin release and augment whole-body creatine retention to the same extent as a large bolus of simple sugars. Seven young, healthy males underwent three randomized, 3-day experimental trials. Each day, 24-h urine collections were made, and on the second day participants received 5 g creatine + water (creatine trial), 5 g creatine + ～95 g dextrose (creatine + carbohydrate) or 5 g creatine + 14 g protein hydrolysate, 7 g leucine, 7 g phenylalanine, and 57 g dextrose (creatine + protein, amino acids, and carbohydrate) via naso-gastric tube at three equally spaced intervals. Blood samples were collected at predetermined intervals after the first and third naso-gastric bolus. After administration of the first and third bolus, serum insulin concentration was increased by 15 min (P < 0.05) in the creatine + carbohydrate and creatine + protein, amino acids, and carbohydrate trials compared with creatine alone, and plasma creatine increased more following creatine alone (15 min, P < 0.05) than in the creatine + carbohydrate and creatine + protein, amino acids, and carbohydrate trials. Urinary creatine excretion was greater with creatine alone (P < 0.05) than with creatine + carbohydrate and creatine + protein, amino acids, and carbohydrate. Administration of creatine + protein, amino acids, and carbohydrate can stimulate insulin release and augment whole-body creatine retention to the same extent as when larger quantities of simple sugars are ingested.  相似文献   

Nutritional strategies for promoting fat utilization and delaying the onset of fatigue during prolonged exercise     

E. V. Lambert  J. A. Hawley  J. Goedecke  T. D. Noakes  S. C. Dennis 《Journal of sports sciences》2013,31(3):315-324

Carbohydrate ingestion before and during endurance exercise delays the onset of fatigue (reduced power output). Therefore, endurance athletes are recommended to ingest diets high in carbohydrate (70% of total energy) during competition and training. However, increasing the availability of plasma free fatty acids has been shown to slow the rate of muscle and liver glycogen depletion by promoting the utilization of fat. Ingested fat, in the form of long-chain (C 16-22 ) triacylglycerols, is largely unavailable during acute exercise, but medium-chain (C 8-10 ) triacylglycerols are rapidly absorbed and oxidized. We have shown that the ingestion of medium-chain triacylglycerols in combination with carbohydrate spares muscle carbohydrate stores during 2 h of submaximal (< 70% VO 2 peak) cycling exercise, and improves 40 km time-trial performance. These data suggest that by combining carbohydrate and medium-chain triacylglycerols as a pre-exercise supplement and as a nutritional supplement during exercise, fat oxidation will be enhanced, and endogenous carbohydrate will be spared. We have also examined the chronic metabolic adaptations and effects on substrate utilization and endurance performance when athletes ingest a diet that is high in fat (> 70% by energy). Dietary fat adaptation for a period of at least 2-4 weeks has resulted in a nearly two-fold increase in resistance to fatigue during prolonged, low- to moderate-intensity cycling (< 70% VO 2 peak). Moreover, preliminary studies suggest that mean cycling 20 km time-trial performance following prolonged submaximal exercise is enhanced by 80 s after dietary fat adaptation and 3 days of carbohydrate loading. Thus the relative contribution of fuel substrate to prolonged endurance activity may be modified by training, pre-exercise feeding, habitual diet, or by artificially altering the hormonal milieu or the availability of circulating fuels. The time course and dose-response of these effects on maximizing the oxidative contribution of fat for exercise metabolism and in exercise performance have not been systematically studied during moderate- to high-intensity exercise in humans.  相似文献   

Oxidants,antioxidant nutrients and the athlete     

L. Packer 《Journal of sports sciences》2013,31(3):353-363

Strenuous physical exercise induces oxidative stress. There may be a number of sources of this oxidative stress, including mitochondrial superoxide production, ischaemia-reperfusion mechanisms and auto-oxidation of catecholamines. Severe or prolonged exercise can overwhelm antioxidant defences, which include vitamins E and C and thiol antioxidants, which are interlinked in an antioxidant network, as well as antioxidant enzymes. Evidence for oxidative stress and damage during exercise comes from direct measurement of free radicals, from measurement of damage to lipids and DNA, and from measurement of antioxidant redox status, especially glutathione. There is little evidence that antioxidant supplementation can improve performance, but a large body of work suggests that bolstering antioxidant defences may ameliorate exercise-induced damage, suggesting that the benefits of antioxidant intervention may be for the long term rather than the short term.  相似文献   

Energy substrate metabolism during dual work rate exercise: Effects of order     

David Egan  Tony Head 《Journal of sports sciences》2013,31(11):889-894

Changes in workload are evident during many physical activities. The aim of this study was to assess total substrate metabolism when the temporal placement of a period of higher-intensity work (75% VO 2max ) was varied within a low-intensity exercise session (50% VO 2max ). One experimental trial (higher intensity first) comprised 5 min low-intensity work, followed by 15 min high-intensity work, followed by 40 min low-intensity work. The other trial (low intensity first) comprised 40 min low-intensity work, followed by 15 min high-intensity work, followed by 5 min low-intensity work. The trials were designed to achieve an identical total energy expenditure. Energy expenditure, fat and carbohydrate utilization were estimated by expired gas analysis and compared between conditions. Mean total energy expenditure during the higher-intensity phase was 1076 kJ and 1128 kJ in the high-intensity first and low-intensity first trials respectively (t 6 = -3.76, P = 0.0047). Mean total energy expenditure for the whole trial was 3356 kJ and 3452 kJ in the high-intensity first and low-intensity first trials respectively (t 6 = -3.48, P = 0.0065). Mean whole-trial fat utilization was 1753 kJ and 1857 kJ in the high-intensity first and low-intensity first trials respectively (t 6 = -0.76, P = 0.24). Our findings suggest that changing the temporal placement of higher-intensity work within a low-intensity exercise session has a significant effect on total energy expenditure but not on the rate of fat oxidation.  相似文献   

The influence of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill     

S.J. McGregor  C.W. Nicholas  H.K.A. Lakomy  C. Williams 《Journal of sports sciences》2013,31(11):895-903

The aim of this study was to examine the effect of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill. Nine semi-professional soccer players volunteered to participate in the study. Their mean (± _sx ) age, body mass and maximal oxygen uptake were 20.2 ± 0.4 years, 73.2 ± 1.8 kg and 59.1 ± 1.3 ml·kg^-1 ·min^-1 respectively. The players were allocated to two randomly assigned trials: ingesting or abstaining from fluid intake during a 90 min intermittent exercise protocol (Loughborough Intermittent Shuttle Test:LIST).This test was designed to simulate the minimum physical demands faced by soccer players during a game. Before and immediately after performance of the test,the players completed a soccer skill test and a mental concentration test. Performance of the soccer skill test after the 'no-fluid' trial deteriorated by 5% (P ? 0.05),but was maintained during the fluid trial. Mean heart rate, perceived exertion, serum aldosterone, osmolality, sodium and cortisol responses during the test were higher (P ? 0.05) in the 'no-fluid' trial than in the fluid trial. The results of this study suggest that soccer players should consume fluid throughout a game to help prevent a deterioration in skill performance.  相似文献   

Evaluation of the Physical Activity and Public Health Course for Practitioners     

Kelly R. Evenson  David R. Brown  Emily Pearce  Ricky Camplain  Jan Jernigan  Jacqueline Epping 《Research quarterly for exercise and sport》2013,84(2):207-213

Purpose: From 1996 to 2013, a 6-day Physical Activity and Public Health Course for Practitioners has been offered yearly in the United States. An evaluation was conducted to assess the impact of the course on building public health capacity for physical activity and on shaping the physical activity and public health careers of fellows since taking the courses. Method: An evaluation quantified time that fellows spent in different course offerings and surveyed fellows. Results: From 1996 to 2012, 410 fellows attended the course, and in 2013, 186 participated in the Web-based survey (56% response rate). The number of fellows attending the course ranged from 15 to 33 yearly. From 1996 to 2012, the course averaged 38 hr of instructional time that included topics on interventions and environment/policy work to increase physical activity, program evaluation, public health research, and health disparities. The course included consultations, collaborative work, and field-based experiences. Fellows who participated in the survey agreed that the course had a positive impact on the physical activity research or practice work they did (98%), met their expectations (96%), helped them with research/practice collaborations with other physical activity professionals (96%), assisted them in conducting higher-quality interventions/programs (95%), helped increase their professional networking in the field (93%), and had a positive impact on other work they did (91%). Following the course, 66% and 56% had further contact with faculty and other fellows, respectively. Conclusion: The Physical Activity and Public Health Course for Practitioners made important contributions toward building the capacity of physical activity and public health practitioners.  相似文献   

我国高校竞技健美操男单成套难度动作分析     

张中印  马凌波  周燕  熊德良  秦勇 《哈尔滨体育学院学报》2013,(2):74-79,96

采用文献资料、专家访谈、数理统计、录像分析等方法对2010年健美操世锦赛、2011年全国健美操锦标赛精英组男单决赛前6名成套的难度动作编排体系进行对比分析,探析两者之间的差异、差距,为我国男单成套创编提供参考。研究发现：我国男单成套中难度动作的选择比较单一,重复率高;顺序安排无规律;动作失误率高,部分难度动作完成质量较差;部分运动员完成高难度动作的能力有所欠缺,D组动作的稳定性有待加强。  相似文献   

对开展社区老年体育健身服务价值的探讨     

刘军  常生 《喀什师范学院学报》2003,24(3):87-89

对开展社区老年体育健身服务价值进行了探讨，开展社区老年体育健身服务，可以减少我国人口老龄化带来的负面影响，提高老龄人的身心健康水平，促进老年体育锻炼和健身的科学化，并且可以进一步开发老年人力资源，推动社会主义精神文明建设。  相似文献   

浅析篮球后撤步防守基本技术及练习方法     

谢昌雄  余尾  杨善乾 《宜宾学院学报》2005,5(12):90-92

通过对篮球后撤步技术的认真分析,发现准备姿势、控制、转移身体重心,快速有力的蹬地,身体各部位的协调配合,正确合理的脚掌发力部位及前侧脚移动路线是影响后撤步动作的关键因素,结合运动生理学、运动生物力学、人体解剖学和篮球运动中攻防位置的变化对后撤步移动技术进行分析提出练习方法.  相似文献