运动员在热环境训练时的营养与代谢

运动员在热环境训练时大量排汗能引起体内微量元素的丢失以及HCT和Hb水平增加,血糖下降,尿液浓缩等生理反应。文章指出适当补充含糖5%的多种低渗电解质饮料,可使上述现象得到缓解。     

热环境下运动和劳动时出汗丢失水份和无机元素的研究

研究表明,在热环境下运动和劳动,大量排汗是体内无机元素钾、钠、钙、镁等丢失的重要原因,应采取合理的补充措施,否则易导致机体内稳态失调与一系列功能障碍。     

少年运动员维生素B_1、B_2、C需要量的初步研究

运动训练时,长时间的剧烈的肌肉运动,使体内物质和能量消耗增高,尤其是少年运动员正处于生长发育时期。代谢旺盛;同时,由于运动时排汗较多,引起某些营养素的丢失。国内外许多研究报告曾提出,运动时,机体对维生素的需要量增加。目前,在运动训练实践中,对于运动员除在膳食中摄取维生素B_1、     

坦克乘员中暑的预防

夏季 ,由于外界气温高 ,并被太阳照射 ,加之行驶过程中内燃机散发出来的热量 ,常使坦克驾驶室内气温高于外界气温。据调查 ,我军驻南方坦克部队 ,当外界平均气温为３１～３４℃、晴天、风力为１～２级时 ,开窗行驶车内外温差最小 ,闭窗行驶时较大 ,停车时比外界气温高５～６℃。在闭窗行驶中 ,驾驶员的生理反应和不适感随环境热强度的升高而明显加重。停车待命时 ,乘员静坐车内受热 ,其生理反应随外界热强度升高而加重。待命时间愈长 ,车内乘员受热的威胁愈大 ,肛温可达３９℃以上 ,出汗量可达每小时０ ９升以上。如不采取紧急防护措施 ,坦…     

夏季10km急行军训练战士肛温的预测和控制(摘要)

夏季急行军时战士发生中暑,主要是在热环境中机体不能将产生的热量散发出体外,体内热蓄积,深部体温急剧升高,致使机体热调节和心血管负荷超过人体耐受极限的结果。分析热应激与热紧张的关系,并设计其预测方法,对预防中暑和早期发现中暑病人     

不良训练环境对健康的影响

训练环境是指进行训练时所处的外界条件，如空气、水、温湿度、场地等。训练环境是自然环境的一部分，因而它受自然环境的制约。人体在进行训练时，体内物质代谢增强，与环境的关系更为密切，受环境的影响就更大。因此，了解、克服和改善这些不良的训练环境，对于提高训练效果、确保官兵的身体健康具有非常重要的意义。空气不清洁据测算，普通成年人每分钟吸入空气约９升，而在剧烈运动时，每分钟吸入的空气可达１００升，增加了１０多倍。如果训练环境不清洁、空气不清新，含灰尘杂质较多，会直接影响参训者体内氧气的补充。如果空气中夹带…     

初夏最宜进行耐热锻炼

耐热锻炼有何原理 人们对热的耐受力是不同的。实验证明，人体的热耐受能力与热应激蛋白有关，而这种热应激蛋白合成的增加．与受热程度和受热时间有关。如果人经常处于高温环境中，体内的热应激蛋白的合成就会增加，人体的热耐受力就会增强，以后再进入高温环境中时人体细胞的受损程度就会明显减轻。专家建议，获得或提高热耐受能力的最佳方法是进行耐热锻炼，即在逐渐升高的气温条件下进行锻炼，以达到适应更高温度环境的目的。     

小儿夏季热是怎么一回事

每到盛夏季节，总会有一些小儿发热，而且气温越高发热就越厉害，但到医院诊治时各种化验检查结果却均为正常，且发热症状到秋凉后就会自然减轻，直至不治自愈。小儿的这种季节性发热性疾病被人们称作“小儿夏季热”，医学上称为“暑热症”。小儿夏季热是婴幼儿在炎夏酷暑时节常见多发的一种发热性疾病，多见于0．5—3岁的小儿，这主要是因为小儿身体发育不完善，体温测节功能较差，不能很好地维持正常的产热和散热的动态平衡，容易导致排汗不畅，散热慢，难以适应夏秋酷暑环境.     

不可忽视的人体环保

近年来,人们越来越关注环境保护的问题,可是却往往忽略了自己体内的环保问题。其实,不仅外界环境中的污染源要治理,体内的污染源同样不可忽视。那么,哪些是体内污染源呢?体内的污染源主要可分为自主性的饮食、化学药物污染和来自非自主空间环境的空气污染、辐射污染及水源污染等。我们生活环境的四周其实充满了毒素,比如汽车排放的废气、杀虫剂、消毒剂、洗洁剂、农药、防腐剂等。除此之外,抗生素的滥用以及卫生不达标的农畜产品所携带的传染性微生物等,都是人体环保所要面对的问题。目前人类所面临的污染危机,可分为由消化系统进入体内和由…     

补液、补糖和运动

补液、补糖和运动史小才博士美国佳得乐公司运动生理实验室（美国伊里诺埃州，百灵顿市）１引言运动时汗液的丢失是运动员脱水的主要原因，而出汗则是运动机体散热的一条重要途径。当运动员在冷而下的环境下轻微运动时，每小时排汗２５０毫升是常见的，当运动员在炎热而湿...     

The effects of actinidia sinensis planch (kiwi) drink supplementation on athletes training in hot environments

On the basis of studying the problems and experimental data of athletes training in hot environments, we designed an athletic drink choosing actinidia sinensis planch (ASP), also known as kiwi fruit, as the basic component, and assessed its effects in athletes both at site of training and in the laboratory. The main results were as follows: (1) In athletes riding on a Monark ergometer (maintaining HR at 150 beat/min), the work time to exhaustion was longer (149 +/- 3 min vs 120 +/- 1 min), and the work load was larger (947 +/- 36 KJ vs 833 +/- 28 KJ) when supplementing the ASP drik than when they drank the placebo, P less than 0.01) (2) Supplements with the ASP drink expanded the blood volume of athletes. Hematocrit increased significantly after exercise in athletes consuming placebo, but no significant changes were found in those consuming the ASP drink. (3) The ASP drink which contained 5% carbohydrate maintained the blood glucose concentration of athletes at a normal level even when training lasted more than 2.5 hours and without noticeable effect on plasma insulin levels. (4) Supplement of small amount of multi-minerals in the ASP drink helped to decrease the mineral level changes in serum and sweat after intensive training, but it did not cause kaliemia or affect urinary output. (5) Data on urinary vitamin C content indicated that the vitamin C status of athletes supplementing the ASP drink improved. The ASP drink is not only effective but also fragrant, tasty, refreshing and thirst quenching, and it appears to have no side effects.     

Influence of nitrate supplementation on VO2 kinetics and endurance of elite cyclists

The present study examined if an elevated nitrate intake would improve VO₂ kinetics, endurance, and repeated sprint capacity in elite endurance athletes. Ten highly trained cyclists (72 ± 4 mL O₂/kg/min, mean ± standard deviation) underwent testing for VO₂ kinetics (3 × 6 min at 298 ± 28 W), endurance (120 min preload followed by a 400‐kcal time trial), and repeated sprint capacity (6 × 20 s sprints, recovery 100 s) during two 6‐day periods in randomized order with a daily ingestion of either 0.5 L beetroot (BR) juice to increase nitrate levels or a 0.5 L placebo (PLA) drink with blackcurrant juice. Plasma NOx (nitrate + nitrite) levels were higher (P < 0.01) in BR (147 ± 102 and 159 ± 103 μM after 4 and 6 days of beverage intake, respectively) compared with PLA (41 ± 10 and 40 ± 7 μM). VO₂ kinetics and exercise economy were the same in BR and PLA. Time‐trial performance was similar with an average completion time of 18:20 and 18:37 min:s in BR and PLA, respectively, with average power outputs of 290 ± 43 W in BR and 285 ± 44 W in PLA. Peak and mean power during repeated sprinting were similar in BR and PLA. In contrast to observations in moderately trained subjects intake of BR juice had no effect on VO₂ kinetics and performance in elite cyclists.     

The effects of glucose polymer beverage ingestion during prolonged outdoor exercise in the heat

The aim of this study was to examine the effect of ingestion of a glucose polymer drink on fluid and metabolic balance during a 30 km outdoor march in the heat (ambient temperature, 26-31 degrees C; relative humidity, 53-34%). The subjects were randomly assigned to one of three groups: 7.2% glucose polymer-electrolyte beverage (GP) (N = 16), flavored sweetened placebo drink (SP) (N = 15), and tap water (TW) (N = 18). The subjects in the three groups consumed similar volumes of fluid, and no differences were found in sweat rate and percent dehydration. Changes in plasma volume were smaller, though not statistically significant, for GP than for SP and TW (-2.8%, -5.4%, -9.4%, respectively). Changes in sodium concentrations and serum osmolality were similar in the three groups. Subjects consuming GP maintained during exercise a significantly higher (P less than 0.001) blood glucose concentration (range: 6.5-7.4 mmol.l-1) than the SP and TW groups. They were also found to have increased levels of serum insulin (29.3 +/- 18.5 mU.l-1) and no change in serum free fatty acids (0.52 +/- 0.19 mmol.l-1). In contrast, subjects ingesting SP or TW had significantly elevated (P less than 0.001) concentrations of free fatty acids (range: 1.35-1.74 mmol.l-1) compared with subjects consuming GP (0.35-0.52 mmol.l-1), with no significant change in blood glucose and serum insulin levels over the exercise period. We conclude that highly trained endurance athletes may maintain a higher blood glucose level by consuming GP during prolonged exercise in the heat without impairing fluid replacement.     

不同湿度高温环境下机体有氧运动能力相关指标比较

目的:探讨不同湿度高温环境对有氧运动能力的影响。方法:随机选取10名男性大学生为对象,设定环境温度为33℃,相对湿度分别为20%、40%、60%、80%作为模型,实验时间4周,两次测试之间间隔1周。测试时受试者进行递增负荷跑台运动,以8 km/h为起始速度,每分钟增加0.8 km/h到16 km/h为止,然后逐级加坡度,0.5%为起始坡度,每分钟递增0.5%直至受试者不能坚持,运动过程中监测心率、摄氧量、每分钟通气量(VE)以及主观用力感觉指数(RPE),测试前及结束后无名指采血测试血乳酸。结果:不同湿度高温环境下运动VE、最大心率(HRmax)、最大摄氧量(VO2max)无显著性差异,60%相对湿度下运动时VO2max(3831.7±313.16 ml/min)、VE(137.5±9.38 L/min)、HRmax(199.1±8.29 beat/min)均较其余相对湿度大。20%相对湿度组运动后3 min及5 min血乳酸较80%湿度组显著升高(P<0.05),60%相对湿度组运动后3 min血乳酸亦显著高于80%湿度组(P<0.05)。80%相对湿度组运动后1 min RPE仍显著高于40%相对湿度组(P<0.05),20%相对湿度组RPE值增加较缓慢,运动至第7和10 min时RPE值显著低于60%相对湿度组(P<0.05)。结论:与其余湿度相比,33℃高温环境下,80%相对湿度中机体有氧运动能力并未得到充分发挥。     

Cycling with Video Feedback Improves Performance in Untrained,but Not in Trained Women

The objectives of this study were to assess whether exercise performance responses could be altered when subjects were exposed to interactive video feedback and music (VFM), compared to music only feedback (M). Ten women, 5 well-trained (46.4 ± 4.7 ml × kg^-1 × min^-1) and 5 untrained (34.5 ± 5.7 ml × kg^-1 × min^-1) participated in the study. Neither the trained nor the untrained group exhibited significant differences in HR and VO2 between the VFM and M conditions. The trained subjects cycled at similar speeds and for similar distances during the VFM and M conditions, and also cycled at a higher average speed (23.5 ± 2.1 vs. 15.6 ± 3.2 km × h^-1) and further (11.9 ± 1.1 vs. 7.8 ± 1.6 km) than the untrained subjects (p < 0.01). The untrained subjects cycled further and faster in the VFM versus M condition (p < 0.05), and both the average speed (15.6 ± 3.2 vs. 13.9 ± 2.3 km × h^-1) and average distance cycled (7.8 ± 1.6 vs. 7.0 ± 1.2 km) were also improved in the VFM versus M condition (p < 0.05). No group or exercise condition differences were observed for ratings of perceived exertion or psychological performance. We conclude that VFM does not improve cycling performance in trained women, but untrained women cycle faster and further during a 30-min exercise session when exposed to a combination of interactive video and music feedback.     

Running performance and thermal sensation in the heat are improved with menthol mouth rinse but not ice slurry ingestion

The purpose of this study was to compare the effects of a cooling strategy designed to predominately lower thermal state with a strategy designed to lower thermal sensation on endurance running performance and physiology in the heat. Eleven moderately trained male runners completed familiarization and three randomized, crossover 5‐km running time trials on a non‐motorized treadmill in hot conditions (33 °C). The trials included ice slurry ingestion before exercise (ICE), menthol mouth rinse during exercise (MEN), and no intervention (CON). Running performance was significantly improved with MEN (25.3 ± 3.5 min; P = 0.01), but not ICE (26.3 ± 3.2 min; P = 0.45) when compared with CON (26.0 ± 3.4 min). Rectal temperature was significantly decreased with ICE (by 0.3 ± 0.2 °C; P < 0.01), which persisted for 2 km of the run and MEN significantly decreased perceived thermal sensation (between 4 and 5 km) and ventilation (between 1 and 2 km) during the time trial. End‐exercise blood prolactin concentration was elevated with MEN compared with CON (by 25.1 ± 24.4 ng/mL; P = 0.02). The data demonstrate that a change in the perception of thermal sensation during exercise from menthol mouth rinse was associated with improved endurance running performance in the heat. Ice slurry ingestion reduced core temperature but did not decrease thermal sensation during exercise or improve running performance.     

Effects of oral rehydration and external cooling on physiology,perception, and performance in hot,dry climates

Only limited research evaluates possible benefits of combined drinking and external cooling (by pouring cold water over the body) during exercise. Therefore, this study examined cold water drinking and external cooling on physiological, perceptual, and performance variables in hot, dry environments. Ten male runners completed four trials of walking 90 min at 30% VO_2max followed by running a 5‐km time trial in 33 ± 1 °C and 30 ± 4% relative humidity. Trials examined no intervention (CON), oral rehydration (OR), external cooling (EC), and oral rehydration plus external cooling (OR + EC). Investigators measured rectal temperature, skin temperatures, heart rate, thirst, thermal sensation, and ratings of perceived exertion (RPE). Oral rehydration (OR and OR + EC) significantly lowered heart rate (P < 0.001) and thirst (P < 0.001) compared with nondrinking (CON and EC) during low‐intensity exercise. External cooling (EC and OR + EC) significantly reduced chest and thigh temperature (P < 0.001), thermal sensation (P < 0.001), and RPE (P = 0.041) compared with non‐external cooling (CON and OR) during low‐intensity exercise. Performance exhibited no differences (CON = 23.86 ± 4.57 min, OR = 22.74 ± 3.20 min, EC = 22.96 ± 3.11 min, OR + EC = 22.64 ± 3.73 min, P = 0.379). Independent of OR, pouring cold water on the body benefited skin temperature, thermal sensation, and RPE during low‐intensity exercise in hot, dry conditions but failed to influence high‐intensity performance.     

Effect of exercise and fluid consumption on salivary flow and pH

Recent claims have been made regarding the putative erosive effects of regularly ingesting low-pH beverages on the integrity of tooth enamel. The purpose of this study was to determine whether fluid consumption during exercise affects the body's defenses against enamel erosion: saliva flow and salivary pH. Males and females (n=50) exercised in the heat (26.7 degrees C, 40 % RH) for 75 min on four occasions. Within each session, subjects consumed ad-lib either water, a sports drink (Gatorade), diluted orange juice, or a homemade sports drink, with the latter three fluids all having low pH values (3.0 to 4.0). Prior to and following exercise, subjects performed a standard stimulated saliva collection procedure. Immediately following collection, saliva flow rate and pH were determined for each sample. Repeated-measures ANOVA were used to evaluate the data. Compared to pre-exercise salivary flow rates (2.6+/- 0.8 ml/min), the post-exercise rate was not different when consuming the sports drink (2.6+/- 0.9 ml/min), but decreased when water or the homemade sports drink was ingested (2.4+/- 0.9 ml/min; p<0.05). A time-by-drink interaction (p<0.05) revealed slight differences in saliva pH after exercise, depending on the beverage consumed; post-exercise saliva pH was highest for water (7.2+/- 0.2) and lowest for the homemade sports drink (7.1+/- 0.2), with the sports drink and diluted orange juice values falling in between. The results suggest that minimal changes occur in saliva pH and the rate of stimulated saliva flow with beverage consumption during exercise. Subsequent research is needed to determine whether maintenance of saliva production by drinking beverages during exercise influences the body's defenses against dental erosion via saliva production.     

Failure of protein to improve time trial performance when added to a sports drink

INTRODUCTION: Recent studies have reported that adding approximately 2% protein to a carbohydrate sports drink increased cycle endurance capacity compared with carbohydrate alone. However, the practical implications of these studies work are hampered by the following limitations: (a) the rate of carbohydrate ingestion was less than what is considered optimal for endurance performance, and (b) the performance test (exercise time to fatigue) did not mimic the way in which athletes typically compete (i.e., a race in which a fixed distance or set amount of work is performed as quickly as possible). PURPOSE: We tested the hypothesis that adding 2% protein to a 6% carbohydrate drink (CHO-PRO) would improve 80-km cycling time trial performance, as compared with a 6% carbohydrate drink (CHO) and a nonenergetic sweetened placebo (PLAC). METHODS: Ten trained male cyclists (24 +/- 2 yr; VO2peak = 63 +/- 2 mL.kg(-1).min(-1); mean +/- SE) performed an 80-km laboratory time trial (TT) on three occasions separated by 7 d. In a double-blind crossover manner, subjects ingested CHO-PRO, CHO, or PLAC at a rate of 250 mL every 15 min with no temporal, verbal, or physiological feedback. RESULTS: Time to complete the TT was 4.4% lower (P < 0.002) during CHO (135 +/- 9 min) and CHO-PRO (135 +/- 9) compared with PLAC (141 +/- 10), with no difference between CHO and CHO-PRO (P = 0.92). CONCLUSION: Ingesting 6% carbohydrate at a rate of 1 L.h(-1) (60 g.h(-1)) improved an 80-km TT performance in trained male cyclists. However, adding 2% protein to a 6% carbohydrate drink provided no additional performance benefit during a task that closely simulated the manner in which athletes typically compete.