Health and ergogenic effects of caffeine.

The indiscriminate use of caffeine by people of all ages may present health hazards. The public at large needs to be more informed of the presence of caffeine in commonly consumed foods and beverages, particularly by infants, children and pregnant women. It is the responsibility of all consumers to investigate the caffeine content of suspected products so that intake may be objectively monitored. Although doubts still exist about the efficacy of caffeine as an ergogenic aid, particularly for exercise of high intensity and short duration, the IOC and the National Collegiate Athletic Association of the US have adopted bans on the use of caffeine to aid sport performance. Currently, both of these organizations prohibit the concentration of caffeine in urine to exceed 15 micrograms-ml-1. That is to say, only very large amounts of caffeine are not permitted at present. Additional research is needed to confirm or deny the contraindications presented by the ingestion of caffeine on a chronic basis.     

Effect of caffeine and ephedrine ingestion on anaerobic exercise performance

PURPOSE: Ingestion of a combination of caffeine (C) and ephedrine (E) prolongs time to exhaustion during high-intensity aerobic exercise. CNS stimulation by C and E was proposed as part of the mechanism for the improvement. It was thought that this arousal might also be of benefit during anaerobic exercise. The purpose of this study was to investigate the effect of C, E, and C+E ingestion on performance of anaerobic exercise. METHODS: Two groups were used to evaluate the effect of C and E on anaerobic performance. Group 1 (WIN) consisted of 16 healthy untrained male subjects who performed a 30-s Wingate test. Group 2 (MAOD) consisted of 8 healthy untrained male subjects who performed a supramaximal (125%VO(2peak)) cycle exercise trial to exhaustion to determine maximum accumulated oxygen deficit. The trials commenced 1.5 h after ingesting either C (5 mg x kg(-1)), E (1 mg x kg(-1)), a combination of C+E, or a placebo (P). All trials were randomized and double blind. Blood samples were assayed for lactate and glucose post drug ingestion just before exercise, and again 3, 5, and 10 min post exercise. Catecholamines were measured in the preexercise and 10-min postexercise blood samples. RESULTS: Ephedrine increased power output during the early phase of the Wingate test, whereas C increased time to exhaustion and O(2) deficit during the MAOD test. C, E, and C+E increased blood lactate, glucose, and catecholamine levels. CONCLUSION: The improvement in anaerobic exercise performance is likely a result of both stimulation of the CNS by E and skeletal muscle by C.     

Effect of ingesting caffeine and ephedrine on 10-km run performance

. BACKGROUND: The ingestion of either caffeine (C) or ephedrine (E) has been shown to improve performance during high-intensity aerobic activity lasting 10-20 min, with an additive effect being found when the combination (C + E) was ingested. It was the purpose of this study to determine if the addition of E to C would improve performance in activity lasting longer than 20 min. METHODS: One and one half hours after ingesting a placebo (P), C (4 mg/kg), E (0.8 mg/kg), or C + E, 12 subjects performed a 10-km run while wearing a helmet and backpack weighing 11 kg. The trials were performed in a climatic suite at 12-13 degrees C, on a treadmill where the speed was regulated by the subject. VO(2), VCO(2), V(E), heart rate (HR), and rating of perceived exertion (RPE) were measured during the run at 15 and 30 min, and again when the individual reached 9 km. Blood was sampled at 15 and 30 min and again at the end of the run and assayed for lactate, glucose, and catecholamines. RESULTS: Run times (mean +/- SD), in minutes, were for C (46.0 +/- 2.8), E (45.5 +/- 2.9), C + E (45.7 +/- 3.3), and P (46.8 +/- 3.2). The run times for the E trials (E and C + E) were significantly reduced compared with the non-E trials (C and P). Pace was increased for the E trials compared with the non-E trials over the last 5 km of the run. VO(2) was not affected by drug ingestion. HR was elevated for the ephedrine trials (E and C + E). RPE remained similar for all trails. Caffeine increased the epinephrine and norepinephrine response associated with exercise and also increased blood lactate, glucose, and glycerol levels. Ephedrine reduced the epinephrine response but increased dopamine and FFA levels. CONCLUSION: The previously seen additive nature of E and C was not evident in this study, with the primary ergogenic effect being attributed to E.     

Thermal regulation in the heat during exercise after caffeine and ephedrine ingestion.

BACKGROUND: Ingesting a combination of caffeine and ephedrine (C+E) has been shown to raise metabolic heat production and body temperature. This side effect of C+E ingestion may be positive during a cold stress scenario, however, during heat stress it could prove to be detrimental. Thus, the purpose of this study was to clarify the effect of C+E ingestion on body temperature regulation during moderate exercise in a hot dry environment. METHODS: Ten, healthy, non heat acclimated, males exercised at 50% VO2peak in a 40 degrees C and 30% RH environment until rectal temperature reached 39.3 degrees C; heart rate (HR) remained at 95% of peak value or greater for 3 min, dizziness or nausea precluded further exercise, or 3 h had elapsed. They did this four times at weekly intervals: familiarization (Fam), control (Cont), placebo, and C+E (5 mg . kg(-1) caffeine + 1 mg . kg(-1) ephedrine) trials. The Fam and Cont treatments were done first and sequentially while the placebo and C+E treatments were balanced and double-blind. Tolerance times, mean skin temperature (Tsk), rectal temperature (Tre), Vo2, Vco2, VE, sweat rate (SR), HR, and sensation of thermal comfort were measured. RESULTS: Tolerance times (mean+/-SD in minutes) were similar for the placebo (120.0+/-28.4) and C+E (121.3+/-33.9) trials and both times were significantly longer than Cont (106.6+/-24.0) trial. C+E did not affect Tsk, initial TrC, delta Tre, SR or the sensation of thermal comfort. VO2 and VF, were significantly increased by C+E. HR was elevated by C+E compared with the other trials, but only during the initial 20 min of exercise. CONCLUSION: Although the metabolic rate was slightly increased with C+E treatment, it was sufficiently offset by increased heat loss mechanisms so that internal body temperature was not increased during moderate exercise in a hot, dry environment.     

Effects of ephedrine,caffeine, and their combination on muscular endurance

PURPOSE: The purpose of this study was to investigate the effects of ingesting caffeine (C), ephedrine (E), and their combination on muscular endurance, using a double-blind, repeated measures design. METHODS: Ninety minutes after ingesting either C (4 mg x kg-1), E (0.8 mg x kg-1), a combination of C+E, or a placebo (P), 13 male subjects performed a weight-training circuit consisting of three supersets (SS), each SS consisting of leg press (at 80% of 1 RM to exhaustion) followed by bench press (at 70% 1-RM to exhaustion); 2 min of rest intervened between SS. RESULTS: The trials involving ephedrine ingestion (C+E and E), when compared with the nonephedrine trials (C and P), caused significant increases (P < 0.05) in the mean number of repetitions completed for both the leg-press and bench-press exercises but only during the first SS. During that first set, the mean number (+/-SD) of repetitions for leg press was 19 +/- 8, 16 +/- 7, 14 +/- 6, and 13 +/- 5 for the C+E, E, C, and P trials, respectively. The mean numbers of repetitions for the first set of bench-press exercise were 14 +/- 3, 13 +/- 3, 12 +/- 3, and 12 +/- 3 for the C+E, E, C, and P trials, respectively. As a result, the total weight lifted during all three sets was greater for the trials involving ephedrine ingestion. Systolic blood pressure before exercise was significantly increased with both ephedrine treatment trials when compared with the other trials (C+E = 156 +/- 29 mm Hg; E = 150 +/- 14; C = 141 +/- 16; P = 138 +/- 14). CONCLUSION: It was concluded that acute ingestion of C+E and E increases muscular endurance during the first set of traditional resistance-training exercise. The performance enhancement was attributed primarily to the effects of E; there was no additive effect of C.     

Combined caffeine and ephedrine ingestion improves run times of Canadian Forces Warrior Test

The ingestion of a combination of caffeine (C) and ephedrine (E) has been reported to prolong exercise time to exhaustion during cycle ergometry at 85% VO2max. The present study was undertaken to investigate whether this enhancement would occur in a field setting and if drug ingestion on 1 d would affect performance 1 d later. Two hours after ingesting either a combination of 375 mg of C and 75 mg E (C+E), or a placebo (P), 9 healthy male recreational runners completed six balanced and double-blind trials of the Canadian Forces Warrior Test (WT), a 3.2 km run wearing "fighting order" which weighed about 11 kg. The trials were performed in sets of two runs, i.e., two runs were done 24 h apart, and these sets were separated by a minimum of 7 d. The sets were: C+E trial on day 1 (D1), placebo on day 2 (P2); placebo first (P1), C+E second (D2); and placebo first (P3), placebo second (P4). In addition, 1 wk before the treatment trials the subjects performed a control trial WT. During the WT, heart rates (HR) were recorded every minute. Plasma C and E levels immediately before the WT were similar for both C+E trials, but were undetectable for all P trials. Run times (mean+/-SD) were 15.3+/-0.6, 15.4+/-0.9, 15.5+/-1.2, 15.4+/-0.9, 15.4+/-0.9, 14.8+/-0.7, and 14.6+/-0.8 min for control, P1, P2, P3, P4, D1, D2 trials, respectively. The two C+E trial run times were similar and both were significantly faster (p < 0.05) than control and all placebo trials. HR during the WT was significantly higher (p < 0.05) for the C+E trials compared with the other trials. WT performance was not impaired by C+E ingestion 24 h earlier. In conclusion, performance of the WT was improved by ingestion of C+E.     

Exploring the potential ergogenic effects of glycerol hyperhydration

During athletic competition or recreational pursuits, a body's hydration level can become compromised, resulting in a decrement in performance. Glycerol (1,2,3-propanetriol) has been used to induce hyperhydration in an attempt to offset the deleterious effects of dehydration. When glycerol is consumed orally, it is rapidly absorbed primarily in the small intestine. It is reported to be evenly distributed among all fluid compartments, with the exception of the cerebral spinal fluid and aqueous humour, and promotes hyperhydration by inducing an osmotic gradient. Through an increase in the kidney's medullary concentration gradient, water absorption in the nephron is enhanced. When glycerol is consumed, the plasma glycerol concentration increases in proportion to the dose ingested, which easily exceeds the glycerol saturation point resulting in urinary glycerol excretion. Thus, without supplemental glycerol ingestion, there will be a decrease in the osmotic gradient resulting in a loss of hyperhydration. The ergogenic nature of glycerol has been investigated as to its effect on fluid retention, thermoregulation, cardiovascular responses and performance. While many studies provide evidence of hyperhydration, others do not. Only two studies reviewed showed a thermoregulatory advantage. Furthermore, the preponderance of evidence neither weighed for or against cardiovascular or performance advantages. What makes one study provide favourable results while another study does not is unclear. Possible explanations may include subject characteristics, environmental factors, research design, whether fluids with or without glycerol were given during exercise, the rate at which fluids are initially given to induce hyperhydration, the time between peak hyperhydration/peak plasma glycerol concentration and the trial (i.e. exercise), the glycerol dose (i.e. 1.0 g/kg body mass) and what it is based upon, the percentage glycerol solution (i.e. 5%, 20%), the variation of time between the end of the hydration protocol and the beginning of exercise, or perhaps the intensity of exercise (fixed, variable, percentage maximum oxygen uptake). What is clear is that glycerol has the capacity to enhance fluid retention. In so doing, glycerol hyperhydration may be a logistically preferred method due to concomitant decrease in urine output and free-water clearance, which may give a performance advantage by offsetting dehydration. Future research should focus on maintaining plasma glycerol concentrations at levels necessary to maintain osmotic forces required to support continued hyperhydration. Potential benefits of glycerol should be further explored to identify the circumstances or factors that may contribute to an ergogenic effect.     

Evaluation of the ergogenic properties of ginseng: an update

Ginseng has been used in the Orient for several thousand years as an 'adaptogenic' as well as a 'restorative' agent. It has been used to treat nervous disorders, anaemia, wakefulness, dyspnoea, forgetfulness and confusion, prolonged thirst, decreased libido, chronic fatigue, angina and nausea. Although the mechanisms underlying the alleged effects of ginseng remain to be elucidated, there is an extensive animal literature dealing with the effects of ginseng on the cardiovascular system, central nervous system, endocrine system, metabolism, and immune system. In our previous review dealing with the efficacy of ginseng, we concluded that while studies with animals show that ginseng, or its active components, may prolong survival to physical or chemical stress, there is generally a lack of controlled research demonstrating the ability of ginseng to improve or prolong performance in fatigued humans. In this review, we extend our earlier analysis on the potential efficacy of ginseng use in the enhancement of physical performance and modification of fatigue states. Our analysis reveals that published literature appearing since our earlier review has not resolved the equivocal nature of research evidence involving animals or humans. Also, the lack of unanimity in this research can be explained on the basis of various methodological problems such as inadequate sample size and lack of double-blind, control and placebo paradigms. In addition, the absence of acceptable approaches to the problem of 'sourcing', in concert with an absence of compliance data in human research, further complicates the interpretation of this research literature. Nevertheless, the use of ginseng continues to grow, and current sales are estimated to be over $US300 million annually. There is clearly a need for systematic research dealing with the efficacy of ginseng, and this research needs to take into account basic, fundamental design considerations if there is to be any hope of establishing whether or not ginseng possesses efficacy.     

The effect of caffeine on the cardiovascular responses to head-up tilt

BACKGROUND: Both caffeine and orthostasis have known cardiovascular effects. The possible interaction between these factors remains unknown. This study aimed to determine the effect of caffeine consumption on cardiovascular responses to head-up tilt. METHODS: Sixteen subjects underwent three +75 degree head-up tilts: i) control, ii) acute, after a dose of 5 mg x kg(-1) body mass of caffeine or placebo, and iii) chronic, following 7 d of caffeine or placebo consumption at a daily dose of 5 mg x kg(-1) body mass. Heart rate (HR), systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) were measured using a Portapres BP monitor. RESULTS: The overall pattern of heart rate (HR) response in both caffeine and placebo groups showed a significant increase in HR after tilting for each tilt. Acute caffeine consumption significantly decreased resting HR (p < 0.05). After chronic consumption, resting HR was no longer significantly different. In the control condition, the overall pattern of response to tilt for SBP, DBP, and MAP showed no significant differences in either group. An acute dose of caffeine caused a significant fall (p < 0.05) in all BP variables in response to tilt. This effect was also seen after chronic caffeine consumption in SBP and MAP, but not in DBP. CONCLUSIONS: The results of this study indicate that both acute and chronic consumption of caffeine can lead to impaired cardiovascular function after exposure to an orthostatic challenge. This impaired function, reflected in a decreased resting HR and an inability to maintain MAP, is potentially due to impaired baroreflex function.     

Facts and fallacies of purported ergogenic amino acid supplements.

Although current research suggests that individuals involved in either high-intensity resistance or endurance exercise may have an increased need for dietary protein, the available research is either equivocal or negative relative to the ergogenic effects of supplementation with individual amino acids. Although some research suggests that the induction of hyperaminoacidemia via intravenous infusion of a balanced amino acid mixture may induce an increased muscle protein synthesis after exercise, no data support the finding that oral supplementation with amino acids, in contrast to dietary protein, as the source of amino acids is more effective. Some well-controlled studies suggest that aspartate salt supplementation may enhance endurance performance, but other studies do not, meriting additional research. Current data, including results for several well-controlled studies, indicated that supplementation with arginine, ornithine, or lysine, either separately or in combination, does not enhance the effect of exercise stimulation on either hGH or various measures of muscular strength or power in experienced weightlifters. Plasma levels of BCAA and tryptophan may play important roles in the cause of central fatigue during exercise, but the effects of BCAA or tryptophan supplementation do not seem to be effective ergogenics for endurance exercise performance, particularly when compared with carbohydrate supplementation, a more natural choice. Although glutamine supplementation may increase plasma glutamine levels, its effect on enhancement of the immune system and prevention of adverse effects of the overtraining syndrome are equivocal. Glycine, a precursor for creatine, does not seem to possess the ergogenic potential of creatine supplementation. Research with metabolic by-products of amino acid metabolism is in its infancy, and current research findings are equivocal relative to ergogenic applications. In general, physically active individuals are advised to obtain necessary amino acids through consumption of natural, high-quality protein foods.     

度洛西汀联合小剂量奥氮平治疗伴有疼痛症状抑郁症的疗效

 目的 探讨度洛西汀联合小剂量奥氮平治疗伴有疼痛症状抑郁症的疗效。方法 将70 例伴有疼痛症状的抑郁症患者随机分为研究组(35 例,度洛西汀联合小剂量奥氮平治疗)、对照组 (35例,单用度洛西汀治疗),疗程6 周。于治疗前及治疗后采用汉密尔顿抑郁量表(Hamilton depression scale,HAMD) 、研究用疼痛量表(the medical outcomes study pain measurement Scale,MOSPM) 进行评定疗效,应用不良反应量表(treatment emergent symptom scale,TESS)评定药物不良反应。结果 两组HAMD评分2周末开始出现差异性(P＜0.05);4周末、6周末时两组间评分差异存在统计学意义(P＜0.01)。两组的MOSPM评分的减分治疗第4周末开始具有统计学意义(P＜0.05),治疗第6周末,两组MOSPM评分差异具有显著的统计学意义(P＜0.01)。两组的TESS评分差异无统计学意义。研究组治疗6周末时显效率71.43%,有效率88.57%;对照组治疗6周末时显效率62.85%,有效率85.71%。两组疗效进行比较差异有统计学意义 (P＜0.05)。结论 度洛西汀联合小剂量奥氮平治疗伴有疼痛症状的抑郁症疗效优于单一用药。     

Drug treatment of motion sickness: scopolamine alone and combined with ephedrine in real and simulated situations

In two placebo-controlled, double-blind, randomized trials scopolamine (0.3 mg) alone or combined with ephedrine (25 mg) was tested for its effectiveness in the prevention of seasickness during 24 h at sea and of motion sickness in rotating chair tests in a laboratory. Scopolamine was effective both alone and in combination with ephedrine, which supports the hypothesis on central cholinergic overactivity in the pathogenesis of motion sickness. Ephedrine did not markedly increase the effectiveness of scopolamine. Side-effects were slight and did not disturb the operating ability of the volunteers.     

Determination of surface dose and the effect of bolus to surface dose in electron beams.

When treating tumors from surface to a certain depth (<5 cm), electron beams are preferred in radiotherapy. To increase the surface doses of lower electron beams, tissue-equivalent bolus materials are often used. We observed that the surface doses increased with increasing field sizes and electron energies. At the same time, we also observed that all electron parameters were shifted toward the skin as much as the thickness of the bolus used. The effect of bolus to the surface doses was more significant at low electron energies than at higher electron energies. Rando phantom measurements at 6-, 7.5-, and 9-MeV were slightly lower than the solid phantom measurements, which could only be explained by the inverse square law effect and the Rando phantom contour irregularity.     

Single-dose bright light and/or caffeine effect on nocturnal performance

BACKGROUND:The impact of the separate and combined effects of a 1-h exposure to bright light (approximately 3000 lx) and a 200-mg dose of caffeine on nocturnal performance was studied during a simulated shift-work schedule beginning 1730 in the evening and ending 1000 the next morning. HYPOTHESIS: Light and caffeine exposure were expected to improve nocturnal fatigue degradation. METHODS: There were 11 subjects tested under 4 treatment conditions: 1) 1 h Dim Light-Placebo; 2) 1 h Bright Light-Placebo; 3) 1 h Dim Light-Caffeine; 4) 1 h Bright Light-Caffeine. Exposure to the light occurred between 0130 and 0230 hours. Caffeine or placebo was administered at 0140 hours. RESULTS: Choice Reaction Time (RT) recorded during the four post-treatment sessions were shorter for the Bright Light-Caffeine, Bright Light-Placebo, and Dim Light-Caffeine conditions than for the Dim Light-Placebo condition. During the sessions beginning 0430 and 0830 hours, the shortest RT was recorded for the Bright Light-Caffeine treatment. The largest number of trials without false alarms per session for the working memory task (letter cancellation) was found for the Bright Light-Caffeine condition. Exposure for 1 h to 3000 lx reduced melatonin concentration between 42-47% from 0230 to 0410 hours. A 200-mg dose of caffeine also reduced melatonin levels, although to a lesser degree than 1 h exposure to 3000 lx. CONCLUSION: Although 1 h exposure to bright light at 0130 hours combined with a 200-mg dose of caffeine maintains performance throughout the remainder of the night/early morning, a 1-h exposure to bright light without the caffeine may actually degrade performance.     

褶合光谱法测定氢化可的松麻黄碱滴鼻液中氢化可的松和盐酸麻黄碱的含量

 目的建立褶合光谱测定氢化可的松麻黄碱滴鼻液中氢化可的松和盐酸麻黄碱含量的方法.方法用TU-1901双光束紫外可见分光光度计采集吸收度信息,并通过数据转换将信息转到褶合光谱程序中,并由该程序双组分定量分析系统计算氢化可的松和盐酸麻黄碱的含量.结果氢化可的松和盐酸麻黄碱的平均回收率分别为99.81%、100.16%;相对标准偏差(RSDs)分别为0.42%、0.20%.结论本法结果可靠、准确,适合医院制剂的含量测定.     

大剂量氨溴索联合血液灌流治疗百草枯中毒肺损伤的疗效

目的：观察大剂量盐酸氨溴索联合血液灌流对急性百草枯中毒肺损伤的临床治疗效果。方法收集急性百草枯中毒患者46例,都给予血液灌流,按照是否采用大剂量氨溴索治疗分为观察组（23例）和对照组（23例）,比较两组治疗第1、3、5 d 时的动脉血气分析、呼吸参数、胸部 CT 检查及预后生存结果。结果治疗后两组自主呼吸频率（ RR）与潮气量（VT）、呼气末正压（PEEP）、X 线胸片改变等均有改善（P ﹤0.05）,但观察组改善程度优于对照组,存活率高于对照组,死亡病例平均存活时间延长（P ﹤0.05）;而两组发生多脏器功能障碍综合征（ MODS）和多器官衰竭（MOF）的情况无明显差异（P ﹥0.05）。结论血液灌流的基础上加用大剂量氨溴索,可明显改善百草枯中毒患者预后,值得临床推广。