Athens 2004: the pollution climate and athletic performance     

Geraint Florida-James  Ken Donaldson  Vicki Stone 《Journal of sports sciences》2013,31(10):967-980

Athens sits in a basin approximately 450 km² in area, surrounded by mountains and open sea. Anthropogenic emissions in conjunction with the topographical and meteorological conditions can result in high air pollution within the city. The pollutants of concern for athletes competing in Athens 2004 appear to be nitrogen dioxide (NO₂), ozone and particulate (PM₁₀) pollution. Exposure to elevated ozone concentrations has been reported to give rise to symptoms that include cough, chest pain, difficulty in breathing, headache, eye irritation and a decrease in forced expiratory volume in one second. All of these effects are likely to impact upon performance, and several studies of cyclists suggest this to be the case. In contrast, the impact of ambient concentrations of NO₂ appears to be negligible on normal activities, but at high exercise intensities the impact remains unclear. The use of currently available information and models to predict the effect of ozone and other pollutants on elite athletes is problematical, since such models are based upon significantly lower ventilation rates than those achieved by some elite athletes. In addition, it is already known that the response to ozone can vary somewhat between individuals. Since the individuals who will be competing in Athens are physiologically very different to the participants in most published studies, it is difficult to predict individual responses. There is some evidence to indicate that adaptation to the adverse health and performance effects of ozone can occur, so that performance is partially recovered on re-exposure. The adaptation is not seen in all studies and appears to be dependent on several factors, including the initial sensitivity of the individual to ozone. Antioxidant supplementation has also been shown in some studies to partially ameliorate the adverse effects of ozone by counteracting the oxidative stress mechanism associated with this pollutant. Whether this transfers to performance enhancement per se remains unclear at present. Additional research is required to gain a sound understanding of the effects of a complex mixed air pollution exposure on the pulmonary function and performance of athletes exercising at high work intensities.  相似文献   

Use of NSE/PS2m-transgenic mice in the study of the protective effect of exercise on Alzheimer's disease     

Jun Y Cho  Dae Y Hwang  Tae S Kang  Dong H Shin  Jin H Hwang  Chae H Lim 《Journal of sports sciences》2013,31(11):943-951

In its late stage, Alzheimer's disease results in progressive muscle weakness in the arms and legs. The aim of this study was to determine whether mice expressing the skeletal muscle-specific mutant PS2 gene (a model of Alzheimer's disease) are a useful experimental system to study the protective effect of exercise on Aβ-42 reduction, improvement of behavioural function and changes in metabolic parameters. With this aim in mind, the transgenic mice were subjected to treadmill exercise for 3 months. The results showed that in transgenic mice, but not in normal mice, treadmill exercise resulted in a reduction of Aβ-42 deposits and an improvement in behavioural function, thereby restoring normal concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglyceride. Thus, exercise may represent a practical therapeutic strategy for use with human patients with Alzheimer's disease.  相似文献   

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   

Effects of adding a preceding run-up on performance,blood lactate concentration and heart rate during maximal intermittent vertical jumping     

C Hertogh  K Chamari  M Damiani  R Martin  Y Hachana  S Blonc 《Journal of sports sciences》2013,31(9):937-942

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Effects of load on ground reaction force and lower limb kinematics during concentric squats     

Eleftherios Kellis  Fotini Arambatzi  Christos Papadopoulos 《Journal of sports sciences》2013,31(10):1045-1055

The purpose of this study was to examine the effects of external load on vertical ground reaction force, and linear and angular kinematics, during squats. Eight males aged 22.1?±?0.8 years performed maximal concentric squats using loads ranging from 7 to 70% of one-repetition maximum on a force plate while linear barbell velocity and the angular kinematics of the hip, knee and ankle were recorded. Maximum, average and angle-specific values were recorded. The ground reaction force ranged from 1.67?±?0.20 to 3.21?±?0.29 times body weight and increased significantly as external load increased (P?<?0.05). Bar linear velocity ranged from 0.54?±?0.11 to 2.50?±?0.50?m?·?s^?1 and decreased significantly with increasing external load (P?<?0.05). Hip, knee and ankle angles at maximum ground reaction force were affected by external load (P?<?0.05). The force?–?barbell velocity curves were fitted using linear models with coefficients (r ²) ranging from 0.59 to 0.96. The results suggest that maximal force exertion during squat exercises is not achieved at the same position of the lower body as external load is increased. In contrast, joint velocity coordination does not change as load is increased. The force?–?velocity relationship was linear and independent from the set of data used for its determination.  相似文献   

A distributional analysis of the effect of physical exercise on a choice reaction time task     

Karen Davranche  Michel Audiffren  André Denjean 《Journal of sports sciences》2013,31(3):323-329

Abstract

The aim of this study was to examine the facilitating effects of physical exercise on the reaction process. Eleven participants with specific expertise in decision-making sports performed a choice reaction time task during moderate sub-maximal exercise (90% of their ventilatory threshold power). Participants were tested at rest and while cycling. During exercise, the participants were faster, without being more variable. We suggest that the effect of exercise on cognitive performance was due to a major generalized improvement of the whole distribution of response time and, although the benefit effect was small, it was consistent throughout the entire range of reaction times.  相似文献   

Factors influencing physiological responses to small-sided soccer games     

Ermanno Rampinini  Franco M. Impellizzeri  Carlo Castagna  Grant Abt  Karim Chamari  Aldo Sassi 《Journal of sports sciences》2013,31(6):659-666

Abstract

The aim of this study was to examine the effects of exercise type, field dimensions, and coach encouragement on the intensity and reproducibility of small-sided games. Data were collected on 20 amateur soccer players (body mass 73.1 ± 8.6 kg, stature 1.79 ± 0.05 m, age 24.5 ± 4.1 years, [Vdot]O_2max 56.3 ± 4.8 ml · kg^?1 · min^?1). Aerobic interval training was performed during three-, four-, five- and six-a-side games on three differently sized pitches, with and without coach encouragement. Heart rate, rating of perceived exertion (RPE) on the CR10-scale, and blood lactate concentration were measured. Main effects were found for exercise type, field dimensions, and coach encouragement (P < 0.05), but there were no interactions between any of the variables (P > 0.15). During a six-a-side game on a small pitch without coach encouragement, exercise intensity was 84 ± 5% of maximal heart rate, blood lactate concentration was 3.4 ± 1.0 mmol · l^?1, and the RPE was 4.8. During a three-a-side game on a larger pitch with coach encouragement, exercise intensity was 91 ± 2% of maximal heart rate, blood lactate concentration was 6.5 ± 1.5 mmol · l^?1, and the RPE was 7.2. Typical error expressed as a coefficient of variation ranged from 2.0 to 5.4% for percent maximal heart rate, from 10.4 to 43.7% for blood lactate concentration, and from 5.5 to 31.9% for RPE. The results demonstrate that exercise intensity during small-sided soccer games can be manipulated by varying the exercise type, the field dimensions, and whether there is any coach encouragement. By using different combinations of these factors, coaches can modulate exercise intensity within the high-intensity zone and control the aerobic training stimulus.  相似文献   

上海市青少年学生体育锻炼心理特征及其形成原因     

王哲  舒盛芳 《河北体育学院学报》2013,(3):65-68

运用问卷调查法、访谈法、观察法和数理统计法,从心理学角度对上海市青少年学生的体育锻炼现状进行描述和分析。结果表明,青少年学生体育锻炼的四个心理学指标两两之间呈显著性正相关,从主观意识形态到客观物质形态,其相关性基本呈递减趋势。学生在“认知和态度”“需要和动机”“个性和品质”方面表现积极,而在“行为和习惯”方面的积极性不够。男女青少年学生在“认知和态度”“需要和动机”“行为和习惯”方面均具有显著性差异,男生相对于女生具有更加积极的外在表现。  相似文献   

扬州市高中生体育锻炼情绪效应的调查研究   总被引：1，自引：0，他引：1  

赵建章  仲卫  陈家麟 《扬州教育学院学报》2013,31(1):84-87

探讨体育锻炼对高中学生情绪效应的影响,本研究采用Gauvin和Rejeski编制的锻炼诱导情绪问卷作为测量工具对200名学生进行问卷调查并分析。结果显示：体育锻炼后男女学生在情绪效应上存在显著差异（P〈0．01）,且男生优于女生;情绪效应四维度在不同年级的比较中无差异（P〉0．05）;情绪效应的活力激发、身心平静和生理疲劳三个维度在持续时间的比较中无差异（P〉0．05）,积极投入有显著性差异（P〈0．05）;积极投入在持续时间的比较中发现,高一和高三年级有差异（均差值为-2．586,P〈0．05）,且高三年级优于高一年级。因此结论是：体育锻炼对情绪效应有影响．  相似文献   

热休克蛋白70及运动对衰老的影响研究     

石真玉  别业军  吴剑明  王薇  何亚新 《军事体育进修学院学报》2013,(2):122-124

衰老的机制到目前为止没有确切的理论解释,许多研究表明衰老与HSP70的关系密切.论文对HSP70与衰老之间的相互影响及其机制等方面进行了综述,并着重探讨了运动诱导的HSP70对衰老机体的作用,以期为运动延缓衰老提供有力的理论依据.  相似文献