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Vanadium compounds have been shown to have insulin-like properties in rats and non-insulin-dependent diabetic humans. The purpose of the present study was to examine whether the effects of acute and short-term administration of vanadyl sulfate (VA) on insulin sensitivity also exist in healthy active individuals. Five male and two female participants (age: 24.9 +/- 1.5 years; heigh: 176.1 +/- 2.9 cm; body mass: 70.1+/- 2.9 kg) underwent 3 oral glucose tolerance tests (OGTT). The first OGTT was performed to obtain a baseline index of insulin sensitivity (ISI). On the night preceding the second OGTT, participants ingested 100 mg of VS, and the acute effects of VS on ISI were examined. For the next 6 days, participants were instructed to ingest 50 mg of VS twice daily, and a final OGTT was performed on day 7 to determine the short-term effects of VS on ISI. No differences were found in fasting plasma glucose and insulin concentrations after VS administration. Furthermore, ISI after 1 day and 7 days of VS administration was not different compared with baseline ISI (4.8 +/- 0.1 vs. 4.7 +/- 0.1 vs. 4.7 +/- 0.1, respectively). These results demonstrate that there are no acute and short-term effects of VS administration on insulin sensitivity in healthy humans. [ABSTRACT FROM AUTHOR]

PURPOSE: 1) To investigate the effect of caffeine on exogenous carbohydrate (CHO) oxidation and glucose kinetics during exercise; and 2) to determine whether combined ingestion of caffeine and CHO enhanced cycling performance compared with CHO alone. METHODS:: Ten endurance-trained cyclists performed three experimental trials consisting of 105 min steady-state (SS) cycling at 62% VO2max followed by a time trial (TT) lasting approximately 45 min. During exercise, subjects ingested either of the following: a 6.4% glucose solution (GLU), a 6.4% glucose plus caffeine solution providing 5.3 mg.kg of caffeine (GLU + CAF), or a placebo (PLA). Glucose solutions contained a trace amount of [U-C]glucose, and eight subjects received a primed continuous [6,6-H2]glucose infusion. RESULTS:: Peak exogenous CHO oxidation rates were not significantly different between GLU and GLU + CAF trials (52.6 +/- 2.7 and 49.1 +/- 2.1 mumol.kg.min, respectively). Rates of appearance (Ra) and disappearance (Rd) of glucose were significantly higher with CHO ingestion than PLA (P < 0.01) but were not significantly different between GLU and GLU + CAF trials. Performance times were 43.45 +/- 0.86, 45.45 +/- 1.07, and 47.40 +/- 1.30 min for GLU + CAF, GLU, and PLA, respectively. Therefore, GLU + CAF ingestion enhanced TT performance by 4.6% (P < 0.05) compared with GLU and 9% (P < 0.05) compared with PLA. CONCLUSION:: The coingestion of caffeine (5.3 mg.kg) with CHO during exercise enhanced TT performance by 4.6% compared with CHO and 9.0% compared with water placebo. However, caffeine did not influence exogenous CHO oxidation or glucose kinetics during SS exercise. [ABSTRACT FROM AUTHOR]

PURPOSE: Obesity and type 2 diabetes mellitus are disease states associated with hallmark features such as insulin resistance and an impaired ability to oxidize lipids. It has recently been reported that an optimal exercise intensity for fat oxidation (FATmax) exists; we hypothesize that continuous exercise training at this specific intensity can lead to greater improvements in fat oxidation and insulin sensitivity than a eucaloric interval training program. METHODS: In a counterbalanced, crossover design, eight sedentary, obese, but otherwise healthy male participants performed two 4-wk blocks of endurance training, either at a predetermined intensity eliciting maximal fat oxidation (TPCON) or at 5-min intervals of +/- 20% FATmax (TPINT). During the week preceding the exercise training and 48 h after the final exercise bout, an OGTT, V O2max test, steady-state exercise, and measurements of body composition were undertaken. Diet was controlled the day before all trials (50% carbohydrate, 35% fat, and 15% protein; approximately 2900 kcal.d). Variables were compared using two-way repeated-measures analyses of variance. RESULTS: It was shown that fat oxidation rates were increased by 44% after TPCON (0.24 +/- 0.01 vs 0.35 +/- 0.03 g.min, P < 0.05) but not after TPINT, and the whole-body insulin sensitivity index was increased by 27% after TPCON (P < 0.05). These changes occurred despite no change in body weight, body mass index (BMI), waist to hip ratio (WHR), percent body fat (%BF), or V O2max. CONCLUSIONS: A continuous exercise training protocol that can elicit high rates of fat oxidation increases the contribution of fat to substrate oxidation during exercise and can significantly increase insulin sensitivity compared with a eucaloric interval protocol. [ABSTRACT FROM AUTHOR]

PURPOSE AND METHOD: To investigate the possible role of carbohydrate (CHO) receptors in the mouth in influencing exercise performance, seven male and two female endurance cyclists (VO(2max) 63.2 +/- 2.7 (mean +/- SE) mL.kg*(-1).min(-1)) completed two performance trials in which they had to accomplish a set amount of work as quickly as possible (914 +/- 40 kJ). On one occasion a 6.4% maltodextrin solution (CHO) was rinsed around the mouth for every 12.5% of the trial completed. On the other occasion, water (PLA) was rinsed. Subjects were not allowed to swallow either the CHO solution or water, and each mouthful was spat out after a 5-s rinse. RESULTS: Performance time was significantly improved with CHO compared with PLA (59.57 +/- 1.50 min vs 61.37 +/- 1.56 min, respectively, P = 0.011). This improvement resulted in a significantly higher average power output during the CHO compared with the PLA trial (259 +/- 16 W and 252 +/- 16 W, respectively, P = 0.003). There were no differences in heart rate or rating of perceived exertion (RPE) between the two trials (P > 0.05). CONCLUSION: The results demonstrate that carbohydrate mouth rinse has a positive effect on 1-h time trial performance. The mechanism responsible for the improvement in high-intensity exercise performance with exogenous carbohydrate appears to involve an increase in central drive or motivation rather than having any metabolic cause. The nature and role of putative CHO receptors in the mouth warrants further investigation. [ABSTRACT FROM AUTHOR]

Athletes experience minor fatigue and acute reductions in performance as a consequence of the normal training process. When the balance between training stress and recovery is disproportionate, it is thought that overreaching and possibly overtraining may develop. However, the majority of research that has been conducted in this area has investigated overreached and not overtrained athletes. Overreaching occurs as a result of intensified training and is often considered a normal outcome for elite athletes due to the relatively short time needed for recovery (approximately 2 weeks) and the possibility of a supercompensatory effect. As the time needed to recover from the overtraining syndrome is considered to be much longer (months to years), it may not be appropriate to compare the two states. It is presently not possible to discern acute fatigue and decreased performance experienced from isolated training sessions, from the states of overreaching and overtraining. This is partially the result of a lack of diagnostic tools, variability of results of research studies, a lack of well controlled studies and individual responses to training. The general lack of research in the area in combination with very few well controlled investigations means that it is very difficult to gain insight into the incidence, markers and possible causes of overtraining. There is currently no evidence aside from anecdotal information to suggest that overreaching precedes overtraining and that symptoms of overtraining are more severe than overreaching. It is indeed possible that the two states show different defining characteristics and the overtraining continuum may be an oversimplification. Critical analysis of relevant research suggests that overreaching and overtraining investigations should be interpreted with caution before recommendations for markers of overreaching and overtraining can be proposed. Systematically controlled and monitored studies are needed to determine if overtraining is distinguishable from overreaching, what the best indicators of these states are and the underlying mechanisms that cause fatigue and performance decrements. The available scientific and anecdotal evidence supports the existence of the overtraining syndrome; however, more research is required to state with certainty that the syndrome exists. [ABSTRACT FROM AUTHOR]

PURPOSE AND METHODS: To investigate the effect of glucose infusion on glucose kinetics and performance, six endurance cyclists (VO2max = 61.7 +/- 2.0 (mean +/- SE) mL x kg(-1) x min(-1)) completed two performance trials in which they had to accomplish a set amount of work as quickly as possible (991 +/- 41 kJ). Subjects were infused with either glucose (20% in saline; carbohydrate (CHO)) at a rate of 1 g x min(-1) or saline (0.9% saline; placebo (PLA)). It was hypothesized that time trial performance would be unaffected by the infusion of glucose, as endogenous stores of CHO would not be limiting in the PLA trial. RESULTS: Plasma glucose concentration increased from 4.8 +/- 0.1 mmol x L(-1) to 5.9 +/- 0.3 mmol x L(-1) during the PLA trial and from 4.9 +/- 0.1 mmol x L(-1) at rest to 12.4 +/- 1.1 mmol x L(-1) during the CHO trial. These values were significantly higher at all time points during the CHO trial compared with PLA (P < 0.001). In the final stages of the time trial, Rd in the PLA trial was 49 +/- 5 micromol x kg(-1) x min(-1) compared with 88 +/- 7 micromol x kg(-1) x min(-1) in the CHO trial (P < 0.05). Despite these differences, there was no difference in performance time between PLA and CHO (60.04 +/- 1.47 min, PLA, vs 59.90 +/- 1.49 min, CHO, respectively). Infused carbohydrate oxidation in the last 25% of the CHO trial was at least 675 +/- 120 micromol x kg(-1) and contributed 17 +/- 4% to total carbohydrate oxidation. CONCLUSION: The results demonstrate that glucose infusion had no effect on 1-h cycle time-trial performance, despite an increased availability of plasma glucose for oxidation and evidence of increased glucose uptake into the tissues. [ABSTRACT FROM AUTHOR]

The primary roles for nutrition in sprints are for recovery from training and competition and influencing training adaptations. Sprint success is determined largely by the power-to-mass ratio, so sprinters aim to increase muscle mass and power. However, extra mass that does not increase power may be detrimental. Energy and protein intake are important for increasing muscle mass. If energy balance is maintained, increased mass and strength are possible on a wide range of protein intakes, so energy intake is crucial. Most sprinters likely consume ample protein. The quantity of energy and protein intake necessary for optimal training adaptations depends on the individual athlete and training demands; specific recommendations for all sprinters are, at best, useless, and are potentially harmful. However, if carbohydrate and fat intake are sufficient to maintain energy levels, then increased protein intake is unlikely to be detrimental. The type and timing of protein intake and nutrients ingested concurrently must be considered when designing optimal nutritional strategies for increasing muscle mass and power. On race day, athletes should avoid foods that result in gastrointestinal discomfort, dehydration or sluggishness. Several supplements potentially influence sprint training or performance. Beta-alanine and bicarbonate may be useful as buffering agents in longer sprints. Creatine may be efficacious for increasing muscle mass and strength and perhaps increasing intensity of repeat sprint performance during training. [ABSTRACT FROM AUTHOR]

PURPOSE: To compare the potential erosive effect of a prototype carbohydrate-electrolyte drink (PCE) with a neutral control (water) and a commercially available carbohydrate-electrolyte drink (CCE) during exercise. METHODS:: Nineteen healthy adults (male, N = 16; female, N = 3) took part in this single blind, three-way crossover study. Subjects were given each of the three drinks according to a randomization schedule, approximately balanced for first-order carryover effects. At the beginning of each of the three study periods, the volunteers were fitted with an intraoral appliance containing two human enamel blocks. During each study period, volunteers exercised for 75 min.d(-1) (5 repetitions of 15 min of exercise, with 5-min rests between exercise repetitions), 5 d.wk(-1) for 3 wk. Each day, drink aliquots of 200 mL were consumed during a 5-min period before exercise and after every 15-min bout of exercise, followed by a final 400-mL aliquot ingested over a 10-min period: a total of 1400 mL per study day. Dental erosion was measured as tissue loss from the enamel blocks by profilometry at the end of each study period. RESULTS: Water, PCE, and CCE produced 0.138 microm (SD 0.090 microm), 0.138 microm (SD 0.038 microm), and 4.238 microm (SD 3.872 microm) of enamel loss, respectively. A Wilcoxon t statistic showed a significant statistical difference between the PCE and CCE drinks (P < 0.001), whereas no significant difference could be detected between the PCE drink and water (P = 0.740). CONCLUSION: The PCE solution showed minimal erosion compared with the commercially available drink, and was statistically indistinguishable from water under the conditions of this study. Use of CE solutions formulated to minimize erosion during exercise may provide significant dental benefits. [ABSTRACT FROM AUTHOR]

Studies that have investigated oxidation of a single carbohydrate (CHO) during exercise have reported oxidation rates of up to 1 g x min(-1). Recent studies from our laboratory have shown that a mixture of glucose and sucrose or glucose and fructose ingested at a high rate (1.8 g x min(-1)) leads to peak oxidation rates of approximately 1.3 g x min(-1) and results in approximately 20 to 55% higher exogenous CHO oxidation rates compared with the ingestion of an isocaloric amount of glucose. PURPOSE: The purpose of the present study was to examine whether a mixture of glucose, sucrose and fructose ingested at a high rate would result in even higher exogenous CHO oxidation rates (>1.3 g x min(-1)). METHODS: Eight trained male cyclists (VO2max: 64 +/- 1 mL x kg(-1) BM x min(-1)) cycled on three different occasions for 150 min at 62 +/- 1% VO2max and consumed either water (WAT) or a CHO solution providing 2.4 g x min(-1) of glucose (GLU) or 1.2 g x min(-1) of glucose + 0.6 g x min(-1) of fructose + 0.6 g x min(-1) of sucrose (MIX). RESULTS: High peak exogenous CHO oxidation rates were found in the MIX trial (1.70 +/- 0.07 g x min(-1)), which were approximately 44% higher (P < 0.01) compared with the GLU trial (1.18 +/- 0.04 g x min(-1)). Endogenous CHO oxidation was lower (P < 0.05) in MIX compared with GLU (0.76 +/- 0.12 and 1.05 +/- 0.06 g x min(-1), respectively). CONCLUSION: When glucose, fructose and sucrose are ingested simultaneously at high rates (2.4 g x min(-1)) during cycling exercise, exogenous CHO oxidation rates can reach peak values of approximately 1.7 g x min(-1) and estimated endogenous CHO oxidation is reduced compared with the ingestion of an isocaloric amount of glucose. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Acute bouts of prolonged strenuous exercise are often associated with immune suppression and an increased risk of infection. However, few studies have examined immunological responses to intensified training that results in overreaching or overtraining. We investigated the effects of intensified training on plasma cytokines, glutamine, glutamate, and other related immunological variables in endurance-trained cyclists. METHODS: Eight male subjects (age 27.0 +/- 3.0 yr, [OV0312]O(2max) 58.0 +/- 1.7 mL.kg-1.min-1, mass 73.7 +/- 2.1 kg) completed 6 wk of training: 2 wk each of normal training (N, 7 +/- 2 h.wk-1), intensified training (ITP, 14 +/- 5 h.wk-1) and recovery training (R, 3.5 +/- 2.5 h.wk-1). During the study period, subjects completed six graded cycle ergometer tests to exhaustion (MT), six simulated time trial tests (TT), and eight 2 x 10-min maximal effort bouts (IT). Subjects also completed questionnaires to assess mood state. Plasma concentrations of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), salivary IgA, plasma glutamine, glutamate, ammonia, urea, creatine kinase activity, and routine hematological measures were determined once per week. RESULTS: ITP resulted in overreaching in all subjects identified by a significant decline in performance and disturbances of mood state. Significant increases during the ITP were observed in creatine kinase activity and glutamate, whereas the glutamine/glutamate ratio (Gln/Glu ratio), red blood cell numbers (RBC), hemoglobin concentration (Hb), and packed cell volume (PCV) declined after ITP. No significant changes were observed in TNF-alpha, IL-6, salivary IgA, glutamine, ammonia, urea and various routine hematological measures. CONCLUSION: Alterations in plasma cytokines do not appear to be related to the decline in performance and increased mood state characteristic of overreaching; however, the Gln/Glu ratio may be of use as a marker of overreaching and/or overtraining. [ABSTRACT FROM AUTHOR]

PURPOSE: To determine whether combined ingestion of maltodextrin and fructose during 150 min of cycling exercise would lead to exogenous carbohydrate oxidation rates higher than 1.1 g.min. METHODS: Eight trained cyclists VO2max: 64.1 +/- 3.1 mL.kg.min) performed three exercise trials in a random order. Each trial consisted of 150 min cycling at 55% maximum power output (64.2+/-3.5% VO2max) while subjects received a solution providing either 1.8 g.min of maltodextrin (MD), 1.2 g.min of maltodextrin + 0.6 g.min of fructose (MD+F), or plain water. To quantify exogenous carbohydrate oxidation, corn-derived MD and F were used, which have a high natural abundance of C. RESULTS: Peak exogenous carbohydrate oxidation (last 30 min of exercise) rates were approximately 40% higher with combined MD+F ingestion compared with MD only ingestion (1.50+/-0.07 and 1.06+/-0.08 g.min, respectively, P<0.05). Furthermore, the average exogenous carbohydrate oxidation rate during the last 90 min of exercise was higher with combined MD+F ingestion compared with MD alone (1.38+/-0.06 and 0.96+/-0.07 g.min, respectively, P<0.05). CONCLUSIONS: The present study demonstrates that with ingestion of large amounts of maltodextrin and fructose during cycling exercise, exogenous carbohydrate oxidation can reach peak values of approximately 1.5 g.min, and this is markedly higher than oxidation rates from ingesting maltodextrin alone. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The aim of the EC Concerted Action PASSCLAIM was to develop a set of methods and procedures for assessing the scientific support for function-enhancing and health-related claims for foods and food components. This paper presents a critical review of the existing methods to evaluate the different aspects of physical performance and fitness needed to support claims on foods and food ingredients intended to enhance specific physiological functions. DESIGN AND RESULTS: Based on an inventory of labelling claims on available sport nutrition products, seven physiological functions in the field of physical performance and fitness were identified: 1) strength and power, 2) endurance, energy supply and recovery, 3) hydration/re-hydration, 4) flexibility, 5) tissue growth, 6) free radical scavenger capacity and 7) immune function. For each function the existing methodology was reviewed critically and judged on suitability to generate scientific support for physiological function claims on foods. CONCLUSIONS: A database of methods including advantages and disadvantages of use has been generated for considering the scientific support of claims on foods and food ingredients relating to physical performance and fitness. It will contribute to the formulations of guidelines for assessing the scientific support of enhanced function or reduced disease risk claims on foods. [ABSTRACT FROM AUTHOR]