PKNS9refs.MYD? Hopkins, W G20048How to interpret changes in an athletic performance test1-7 Sportscience8Bayes, correlation, error of the estimate, error of measurement, limits of agreement, reliability, time to exhaustion, time trial, validitybWhen monitoring progression of an athlete with performance or other fitness tests, it is important to take into account the magnitude of the smallest worth-while change in performance and the uncertainty or noise in the test result. For elite athletes competing in sports as individuals, the smallest worthwhile change in performance is about half the typical variation in an athlete's per-formance from competition to competition, or ~0.5-1% when expressed as a change in power output, depending on the sport. In team sports, where there is no direct relationship between team and test performance, an appropriate default for the smallest change in test performance is one-fifth of the between-athlete standard deviation (a standardized or Cohen effect size of 0.20). Noise in a test result is best expressed as the typical or standard error of measurement derived from a reliability study. The noise in most perform-ance tests is greater than the smallest worthwhile difference, so assessments of changes in performance can be problematic. An exact but somewhat impractical solution is to present chances that the true change is beneficial, trivial, and harmful. A simpler approach is to apply systematic rules to decide whether the true change is beneficial, trivial, harmful, or unclear. Unrealistically large changes can also be partially discounted when tests are noisy.(http://sportsci.org/jour/04/wghtests.htmSport and Recreation, Faculty of Health, Auckland University of Technology, Auckland 1020, New Zealand. Email: will=AT=clear.net.nz?Batterham, A M Hopkins, W G2005-Making meaningful inferences about magnitudes6-13 Sportscience9Bclinical significance, confidence limits, statistical significance8A study of a sample provides only an estimate of the true (population) value of an outcome statistic. A report of the study therefore usually includes an infer-ence about the true value. Traditionally, a researcher makes an inference by declaring the value of the statistic statistically significant or non-significant on the basis of a p value derived from a null hypothesis test. This approach is confusing and can be misleading, depending on the magnitude of the statistic, error of measurement, and sample size. We use a more intuitive and practical approach based directly on uncertainty in the true value of the statistic. First we express the uncertainty as confidence limits, which define the likely range of the true value. We then deal with the real-world relevance of this uncertainty by taking into account values of the statistic that are substantial in some posi-tive and negative sense, such as beneficial and harmful. If the likely range overlaps substantially positive and negative values, we infer that the outcome is unclear; otherwise, we infer that the true value has the magnitude of the observed value: substantially positive, trivial, or substantially negative. We refine this crude inference by stating qualitatively the likelihood that the true value will have the observed magnitude (e.g., very likely beneficial). Quantita-tive or qualitative probabilities that the true value has the other two magnitudes or more finely graded magnitudes (such as trivial, small, moderate, and large) can also be estimated to guide a decision about the utility of the outcome.&http://sportsci.org/jour/05/ambwgh.htmSchool of Health and Social Care, University of Teesside, Middlesbrough, UK; Sport and Recreation, AUT University, Auckland 1020, New Zealand. Email: will=AT=clear.net.nz? Hopkins, W G2003.Writing pre and post [item and two slideshows]4sportsci.org/jour/03/inbief#writing.htm (2164 words) Sportscience7+ethics, grant, manuscript, proposal, thesisNews/research resource7Slideshows about writing before and after you get data./http://sportsci.org/jour/03/inbrief#writing.htmSport and Recreation, Faculty of Health, Auckland University of Technology, Auckland 1020, New Zealand. Email: will=AT=clear.net.nz?Curran-Everett, D Benos, D J2004_Guidelines for reporting statistics in journals published by the American Physiological Society457-459Journal of Applied Physiology97?KHansen, A K Fischer, C P Plomgaard, P Andersen, J L Saltin, B Pedersen, B K2005SSkeletal muscle adaptation: training twice every second day vs. training once daily93-99Journal of Applied Physiology98?/Martin, J C Gardiner, A S Martin, B Martin, D T2006NModeling sprint cycling using field-derived parameters and forward integration592-597+Medicine and Science in Sports and Exercise38? Seiler, S Kjerland, G O2006Quantifying training intensity distribution in elite endurance athletes: is there evidence for an ‘‘optimal’’ distribution?49-566Scandinavian Journal of Science and Medicine in Sports16? Batterham, A M Hopkins, W G2005%A decision tree for controlled trials33-39 Sportscience9%analysis, bias, crossover, randomizedFA controlled trial is used to estimate the effect of an intervention. We present here a decision tree for choosing the most appropriate of five kinds of con-trolled trial for numeric outcome measures. A time series or quasi-experimental design is used when there is no opportunity for a separate control group or control treatment. In this design, the weakest of the five, a series of measurements taken before the intervention serves as a baseline to estimate change resulting from the intervention. In trials with a separate control group, the usual design is a fully controlled parallel-groups trial, in which subjects are measured before and after their allocated control or experimental treatment. A posts-only design, in which subjects are measured only after their treatment, can be more efficient when poor reliability of the outcome measure over the time frame of the intervention makes large sample sizes unavoidable. Cross-over studies, in which all the subjects receive all the treatments, are an option when the effects of the treatments wash out in an acceptable time. In fully con-trolled crossovers, subjects are measured before and after each treatment, whereas measurements are taken only after each treatment in a simple cross-over. Fully controlled crossovers, arguably the best of the five designs, are more efficient if the outcome measure becomes too unreliable over the wash-out period, and they provide an assessment of the effect of the treatment on each subject. In simple crossovers, individual assessment is possible only by including a repeat of the control treatment.&http://sportsci.org/jour/05/wghamb.htmSchool of Health and Social Care, University of Teesside, Middlesbrough, UK; Sport and Recreation, AUT University, Auckland 1020, New Zealand. Email: will=AT=clear.net.nz? Hopkins, W G2003?A spreadsheet for analysis of straightforward controlled trials/sportsci.org/jour/03/wghtrials.htm (4447 words) Sportscience7Yanalysis, crossover, design, intervention, randomized, statistics, transformation, t testNews/research resourceSpreadsheets are a valuable resource for analysis of most kinds of data in sport and exercise science. Here I present a spreadsheet for comparison of change scores resulting from a treatment in an experimental and control group. Features of the spreadsheet include: the usual analysis based on the unequal-variances unpaired t statistic; analysis following logarithmic, percentile-rank, square-root, and arcsine-root transformations; plots of change scores to check for uniformity of the effects; back-transformation of the effects into meaningful magnitudes; estimates of reliability for the control group; estimates of individual responses; comparison of the groups in the pretest; and estimates of uncertainty in all effects, expressed as confidence limits and chances the true value of the effect is important. Analysis of straightforward crossover trials based on the paired t statistic is provided in a modified version of the spreadsheet.)http://sportsci.org/jour/03/wghtrials.htmSport and Recreation, Faculty of Health, Auckland University of Technology, Auckland 1020, New Zealand. Email will=AT=clear.net.nz? Hopkins, W G2005-A spreadsheet for fully controlled crossovers24 Sportscience9.http://sportsci.org/jour/05/inbrief.htm#spread]Sport and Recreation, AUT University, Auckland 1020, New Zealand. Email: will=AT=clear.net.nz? Becker, B J1988.Synthesizing standardized mean-change measures257-278:British Journal of Mathematical and Statistical Psychology41stats, effect size, repeatedmodelfull? Hopkins, W G2006@A spreadsheet for combining outcomes from several subject groups51-53 Sportscience10#http://sportsci.org/2006/wghcom.htm]Sport and Recreation, AUT University, Auckland 0627, New Zealand. Email: will=AT=clear.net.nz'? Hopkins, W G2006\Spreadsheets for analysis of controlled trials, with adjustment for a subject characteristic46-50 Sportscience10(http://sportsci.org/2006/wghcontrial.htm]Sport and Recreation, AUT University, Auckland 0627, New Zealand. Email: will=AT=clear.net.nzm?Brouns, F. Kovacs, E.1997Functional drinks for athletes414-421#Trends in Food Science & Technology812DecOver the past few decades, numerous studies have been carried out to establish the optimal composition of drinks that are designed to rehydrate the body rapidly. These studies have led to the insight that drinks should contain carbohydrate (CHO) and sodium to stimulate fluid absorption and fluid retention. However, the CHO content as well as the osmolality of the drink should be relatively low. According to these findings, the composition criteria for rehydration drinks have quite a narrow range. Drinks that are designed to supply energy or substances that stimulate energy metabolism differ considerably in their composition. This review highlights the most relevant aspects.://000071305200005ISI:000071305200005? Fisher, R A1921QOn the probable error of a coefficient of correlation deduced from a small sample3-32Metron1 stats ???d? Coyle, E. F.2004%Fluid and fuel intake during exercise39-55Journal of Sports Sciences221JanThe amounts of water, carbohydrate and salt that athletes are advised to ingest during exercise are based upon their effectiveness in attenuating both fatigue as well as illness due to hyperthermia, dehydration or hyperhydration. When possible, fluid should be ingested at rates that most closely match sweating rate. When that is not possible or practical or sufficiently ergogenic, some athletes might tolerate body water losses amounting to 2% of body weight without significant risk to physical well-being or performance when the environment is cold (e.g. 5-10degreesC) or temperate (e.g. 21-22degreesC). However, when exercising in a hot environment ( >30degreesC), dehydration by 2% of body weight impairs absolute power production and predisposes individuals to heat injury. Fluid should not be ingested at rates in excess of sweating rate and thus body water and weight should not increase during exercise. Fatigue can be reduced by adding carbohydrate to the fluids consumed so that 30-60 g of rapidly absorbed carbohydrate are ingested throughout each hour of an athletic event. Furthermore, sodium should be included in fluids consumed during exercise lasting longer than 2 h or by individuals during any event that stimulates heavy sodium loss (more than 3-4 g of sodium). Athletes do not benefit by ingesting glycerol, amino acids or alleged precursors of neurotransmitter. Ingestion of other substances during exercise, with the possible exception of caffeine, is discouraged. Athletes will benefit the most by tailoring their individual needs for water, carbohydrate and salt to the specific challenges of their sport, especially considering the environment's impact on sweating and heat stress.://000187366800004ISI:000187366800004 ?(Jentjens, R. Achten, J Jeukendrup, A. E.2004hHigh oxidation rates from a mixture of glucose, sucrose, and fructose ingested during prolonged exercise 1551–1558+Medicine and Science in Sports and Exercise362 The pattern of muscle glycogen synthesis following glycogen-depleting exercise occurs in two phases. Initially, there is a period of rapid synthesis of muscle glycogen that does not require the presence of insulin and lasts about 30-60 minutes. This rapid phase of muscle glycogen synthesis is characterised by an exercise-induced translocation of glucose transporter carrier protein-4 to the cell surface, leading to an increased permeability of the muscle membrane to glucose. Following this rapid phase of glycogen synthesis, muscle glycogen synthesis occurs at a much slower rate and this phase can last for several hours. Both muscle contraction and insulin have been shown to increase the activity of glycogen synthase, the rate-limiting enzyme in glycogen synthesis. Furthermore, it has been shown that muscle glycogen concentration is a potent regulator of glycogen synthase. Low muscle glycogen concentrations following exercise are associated with an increased rate of glucose transport and an increased capacity to convert glucose into glycogen. The highest muscle glycogen synthesis rates have been reported when large amounts of carbohydrate (1.0-1.85 g/kg/h) are consumed immediately post-exercise and at 15-60 minute intervals thereafter, for up to 5 hours post-exercise. When carbohydrate ingestion is delayed by several hours, this may lead to similar to50% lower rates of muscle glycogen synthesis. The addition of certain amino acids and/or proteins to a carbohydrate supplement can increase muscle glycogen synthesis rates, most probably because of an enhanced insulin response. However, when carbohydrate intake is high ( greater than or equal to1.2 g/kg/h) and provided at regular intervals, a further increase in insulin concentrations by additional supplementation of protein and/or amino acids does not further increase the rate of muscle glycogen synthesis. Thus, when carbohydrate intake is insufficient (<1.2 g/kg/h), the addition of certain amino acids and/or proteins May be beneficial for muscle glycogen synthesis. Furthermore, ingestion of insulinotropic protein and/or amino acid mixtures might stimulate post-exercise net muscle protein anabolism. Suggestions have been made that carbohydrate availability is the main limiting factor for glycogen synthesis. A large part of the ingested glucose that enters the bloodstream appears to be extracted by tissues other than the exercise muscle (i.e. liver, other muscle groups or fat tissue) and may therefore limit the amount of glucose available to maximise muscle glycogen synthesis rates. Furthermore, intestinal glucose absorption may also be a rate-limiting factor for muscle glycogen synthesis when large quantities (>1 g/min) of glucose are ingested following exercise.://000181506500004ISI:000181506500004 ?Jentjens, R. Jeukendrup, A. E.2003KDeterminants of post-exercise glycogen synthesis during short-term recovery117-144Sports Medicine332 The pattern of muscle glycogen synthesis following glycogen-depleting exercise occurs in two phases. Initially, there is a period of rapid synthesis of muscle glycogen that does not require the presence of insulin and lasts about 30-60 minutes. This rapid phase of muscle glycogen synthesis is characterised by an exercise-induced translocation of glucose transporter carrier protein-4 to the cell surface, leading to an increased permeability of the muscle membrane to glucose. Following this rapid phase of glycogen synthesis, muscle glycogen synthesis occurs at a much slower rate and this phase can last for several hours. Both muscle contraction and insulin have been shown to increase the activity of glycogen synthase, the rate-limiting enzyme in glycogen synthesis. Furthermore, it has been shown that muscle glycogen concentration is a potent regulator of glycogen synthase. Low muscle glycogen concentrations following exercise are associated with an increased rate of glucose transport and an increased capacity to convert glucose into glycogen. The highest muscle glycogen synthesis rates have been reported when large amounts of carbohydrate (1.0-1.85 g/kg/h) are consumed immediately post-exercise and at 15-60 minute intervals thereafter, for up to 5 hours post-exercise. When carbohydrate ingestion is delayed by several hours, this may lead to similar to50% lower rates of muscle glycogen synthesis. The addition of certain amino acids and/or proteins to a carbohydrate supplement can increase muscle glycogen synthesis rates, most probably because of an enhanced insulin response. However, when carbohydrate intake is high ( greater than or equal to1.2 g/kg/h) and provided at regular intervals, a further increase in insulin concentrations by additional supplementation of protein and/or amino acids does not further increase the rate of muscle glycogen synthesis. Thus, when carbohydrate intake is insufficient (<1.2 g/kg/h), the addition of certain amino acids and/or proteins May be beneficial for muscle glycogen synthesis. Furthermore, ingestion of insulinotropic protein and/or amino acid mixtures might stimulate post-exercise net muscle protein anabolism. Suggestions have been made that carbohydrate availability is the main limiting factor for glycogen synthesis. A large part of the ingested glucose that enters the bloodstream appears to be extracted by tissues other than the exercise muscle (i.e. liver, other muscle groups or fat tissue) and may therefore limit the amount of glucose available to maximise muscle glycogen synthesis rates. Furthermore, intestinal glucose absorption may also be a rate-limiting factor for muscle glycogen synthesis when large quantities (>1 g/min) of glucose are ingested following exercise.://000181506500004ISI:000181506500004n?IJentjens, Rlpg Moseley, L. Waring, R. H. Harding, L. K. Jeukendrup, A. E.2004GOxidation of combined ingestion of glucose and fructose during exercise 1277-1284Journal of Applied Physiology964Apr 1PThe purpose of the present study was to examine whether combined ingestion of a large amount of fructose and glucose during cycling exercise would lead to exogenous carbohydrate oxidation rates > 1 g/min. Eight trained cyclists ( maximal O-2 consumption: 62 +/- 3 ml . kg(-1) . min(-1)) performed four exercise trials in random order. Each trial consisted of 120 min of cycling at 50% maximum power output ( 63 +/- 2% maximal O-2 consumption), while subjects received a solution providing either 1.2 g/min of glucose (Med-Glu), 1.8 g/min of glucose (High-Glu), 0.6 g/min of fructose + 1.2 g/min of glucose (Fruc + Glu), or water. The ingested fructose was labeled with [U-C-13] fructose, and the ingested glucose was labeled with [U-C-14] glucose. Peak exogenous carbohydrate oxidation rates were similar to 55% higher ( P < 0.001) in Fruc + Glu (1.26 +/- 0.07 g/min) compared with Med-Glu and High-Glu (0.80 +/- 0.04 and 0.83 +/- 0.05 g/min, respectively). Furthermore, the average exogenous carbohydrate oxidation rates over the 60- to 120-min exercise period were higher (P < 0.001) in Fruc + Glu compared with Med-Glu and High-Glu (1.16 +/- 0.06, 0.75 +/- 0.04, and 0.75 +/- 0.04 g/min, respectively). There was a trend toward a lower endogenous carbohydrate oxidation in Fruc + Glu compared with the other two carbohydrate trials, but this failed to reach statistical significance ( P = 0.075). The present results demonstrate that, when fructose and glucose are ingested simultaneously at high rates during cycling exercise, exogenous carbohydrate oxidation rates can reach peak values of similar to 1.3 g/min.://000220130400004ISI:000220130400004?Jeukendrup, A. E.20043Carbohydrate intake during exercise and performance669-677 Nutrition207-8Jul-Aug&It is generally accepted that carbohydrate (CHO) feeding during exercise can improve endurance capacity (time to exhaustion) and exercise performance during prolonged exercise (>2 h). More recently, studies have also shown ergogenic effects of CHO feeding during shorter exercise of high intensity (similar to1 h at >75% of maximum oxygen consumption). During prolonged exercise the mechanism behind this performance improvement is likely to be related to maintenance of high rates of CHO oxidation and the prevention of hypoglycemia. Nevertheless, other mechanisms may play a role, depending on the type of exercise and the specific conditions. The mechanism for performance improvements during higher-intensity exercise is less clear, but there is some evidence that CHO can have central effects. In the past few years, studies have investigated ways to optimize CHO delivery and bioavailability. An analysis of all studies available shows that a single CHO ingested during exercise will be oxidized at rates up to about 1 g/min, even when large amounts of CHO are ingested. Combinations of CHO that use different intestinal transporters for absorption (e.g., glucose and fructose) have been shown to result in higher oxidation rates, and this seems to be a way to increase exogenous CHO oxidation rates by 20% to 50%. The search will continue for ways to further improve CHO delivery and to improve the oxidation efficiency resulting in less accumulation of CHO in the gastrointestinal tract and potentially decreasing gastrointestinal problems during prolonged exercise.://000222328900012ISI:000222328900012?,Jeukendrup, A E Jentjens, R L P G Moseley, L2005'Nutritional considerations in triathlon163-181Sports Medicine35v?(Leiper, J. B. Aulin, K. P. Soderlund, K.2000`Improved gastric emptying rate in humans of a unique glucose polymer with gel-forming properties 1143-1149(Scandinavian Journal of Gastroenterology3511NovVBackground: The energy density of a nutrient drink is one of the main factors that affect the gastric emptying of the solution, while osmolality and viscosity are thought to have only a minimal influence. Method: The rate of gastric emptying of two isoenergetic carbohydrate solutions with different osmolality and viscosity was determined using a double sampling gastric aspiration technique. Six healthy male subjects were studied on two occasions using approximately 550 ml of a solution containing 13.5% of carbohydrate either in the form of a mixture of monomeric glucose and short chain glucose oligomers (G-drink) or of long chain glucose polymers composed of 78% amylopectin and 22% amylose (C-drink). Result: The half emptying time (t(1/2) median and range) for the viscous, markedly hypotonic (62 mosmol/kg) C-drink was faster (17.0 (6.2-31.4) min) than for the moderately hypertonic (336 mosmol/kg) G-drink (32.6 (25.2-40.7) min). The amount (median and range) of carbohydrate delivered to the small intestine was greater during the first 10 min after ingestion of C-drink (31.8 (15.8-55.9) g) than after ingestion of G-drink (14.3 (6.8-22.2) g). However, there was no difference in the blood glucose (P = 0.73) or serum insulin (P = 0.38) concentration at any time point after ingestion of the two test drinks. Conclusion: The results of this study show that the carbohydrate present in C-drink, although it has the propensity to form a gel, empties from the stomach faster than that of an isoenergetic carbohydrate solution (G-drink) without potentiating increased circulating blood glucose or insulin levels.://000165779000005ISI:000165779000005T?Maughan, R. J. Leiper, J. B.19990Limitations to fluid replacement during exercise173-187PCanadian Journal of Applied Physiology-Revue Canadienne De Physiologie Appliquee242AprKFluid replacement during exercise is essential for endurance exercise performance and reducing the risk of heat illness. Fluids supply water which ameliorates dehydration, and also substrate for the working muscles. Absorption of water and nutrients occurs in the upper part of the small intestine, and replacement may be limited by the rate at which fluid is emptied from the stomach or absorbed in the intestine. Gastric emptying of liquids is influenced primarily by the volume of fluid in the stomach and by its energy density Increasing the volume will speed emptying, but increasing the nutrient content will slow emptying. Osmolality, temperature, and pH of drinks, as well as exercise intensity, are of minor importance. Intestinal water absorption is a passive process: water-follows osmotic gradients brit will also follow the active absorption of nutrients, especially glucose, which is actively co-transported with sodium. Water transport is maximised by the presence in the intestine of hypotonic solutions of glucose and sodium. Hypertonic solutions promote net water secretion into the intestinal lumen, resulting in a temporary net loss of water from the body. The amount of fluid ingested by athletes is normally much less than can be tolerated, therefore issues such as palatability and practising drinking during training are important.://000079199200006ISI:000079199200006o?(Maughan, R. J. Leiper, J. B. Vist, G. E.2004oGastric emptying and fluid availability after ingestion of glucose and soy protein hydrolysate solutions in man101-108Experimental Physiology891JanTThe double sampling gastric aspiration method was used to measure the effect of energy content on the rate of gastric emptying of glucose and soy protein hydrolysate solutions. The net rate of absorption of water from these solutions was assessed using deuterium oxide as a tracer for water. Six healthy male subjects were each studied on four separate occasions using a test drink volume of 600 ml. The half emptying times (t(1/2), median (range)) of the iso-energetic soy protein hydrolysate (6P, 60 g l(-1), 36 (14-39) min) and glucose (7G, 70 g l(-1), 25 (19-29) min) solutions were similar. These two solutions (6P, 7G) delivered energy to the small intestine at similar rates, and resulted in similar rates of accumulation of the deuterium tracer in the circulation. The dilute glucose solution (LG, 23 g l(-1)) was emptied faster (t(1/2) 13 (11-19) min) and resulted in a faster rate of tracer accumulation in the circulation than any of the other solutions, including the iso-osmotic soy protein solution (LG 311 +/- 5 mosmol kg(-1), 6P 321 +/- 24 mosmol kg(-1)). The concentrated soy protein hydrolysate solution (12P, 120 g l(-1)) emptied more slowly (t(1/2) 80 (44-120) min) than the more dilute solutions. The rate of energy delivery to the small intestine from 12P was similar to that from 6P for the first 50 min after ingestion, and similar to that from 7G at all sample points. These results indicate that the iso-energetic solutions of glucose and soy protein hydrolysate used in this study are emptied from the stomach at similar rates and result in similar rates of fluid availability after ingestion.://000188082300011ISI:000188082300011 ?@Morris, J. G. Nevill, M. E. Thompson, D. Collie, J. Williams, C.2003The influence of a 6.5% carbohydrate-electrolyte solution on performance of prolonged intermittent high-intensity running at 30 degrees C371-381Journal of Sports Sciences215May_ Nine male student games players consumed either flavoured water (0.1 g carbohydrate, N-a+ 6 mmol . l(-1)), a solution containing 6.5% carbohydrate-electrolytes (6.5 g carbohydrate, Na+ 21 mmol . l(-1)) or a taste placebo (Na+ 2 mmol . l(-1)) during an intermittent shuttle test performed on three separate occasions at an ambient temperature of 30degreesC (dry bulb). The test involved five 15-min sets of repeated cycles of walking and variable speed running, each separated by a 4-min rest (part A of the test), followed by 60 s run/60 s rest until exhaustion (part B of the test). The participants drank 6.5 ml . kg(-1) of fluid as a bolus just before exercise and thereafter 4.5 ml . kg(-1) during every exercise set and rest period (19 min). There was a trial order effect. The total distance completed by the participants was greater in trial 3 (8441 +/- 873 m) than in trial 1 (6839 +/- 512, P < 0.05). This represented a 19% improvement in exercise capacity. However, the trials were performed in a random counterbalanced order and the participants completed 8634 +/- 653 m, 7786 +/- 741 m and 7099 +/- 647 m in the flavoured water (FW), placebo (P) and carbohydrate-electrolyte (CE) trials, respectively (P = 0.08). Sprint performance was not different between the trials but was impaired over time (FW vs P vs CE: set 1, 2.41 +/- 0.02 vs 2.39 +/- 0.03 vs 2.39 +/- 0.03 s; end set, 2.46 +/- 0.03 vs 2.47 +/- 0.03 vs 2.47 +/- 0.02 s; main effect time, P < 0.01). The rate of rise in rectal temperature was greater in the carbohydrate-electrolyte trial (rise in rectal temperature/duration of trial, degreesC . h(-1); FW vs CE, P < 0.05; P vs CE, N.S.). Blood glucose concentrations were higher in the carbohydrate-electrolyte than in the other two trials (FW vs P vs CE: rest, 4.4 +/- 0.1 vs 4.3 +/- 0.1 vs 4.2 +/- 0.1 mmol . l(-1); end of exercise, 5.4 +/- 0.3 vs 6.4 +/- 0.6 vs 7.2 +/- 0.5 mmol . l(-1); main effect trial, P < 0.05; main effect time, P < 0.01). Plasma free fatty acid concentrations at the end of exercise were lower in the carbohydrate-electrolyte trial than in the other two trials (FW vs P vs CE: 0.57 +/- 0.08 vs 0.53 +/- 0.11 vs 0.29 +/- 0.04 mmol . l(-1); interaction, P < 0.01). The correlation between the rate of rise in rectal temperature (degreesC . h(-1)) and the distance completed was -0.91, -0.92 and -0.96 in the flavoured water, placebo and carbohydrate-electrolyte conditions, respectively (P < 0.01). Heart rate, blood pressure, plasma ammonia, blood lactate, plasma volume and rate of perceived exertion were not different between the three fluid trials. Although drinking the carbohydrate-electrolyte solution induced greater metabolic changes than the flavoured water and placebo solutions, it is unlikely that in these unacclimated males carbohydrate availability was a limiting factor in the performance of intermittent running in hot environmental conditions.://000182885500002ISI:000182885500002z? Rehrer, N J20016Fluid and electrolyte balance in ultra-endurance sport701-715Sports Medicine31 ?tRehrer, N J Wagenmakers, A J M Beckers, E J Halliday, D Leiiper, J B Brouns, F Maughan, R J Westerterp, K Saris, W H1992RGastric emptying, absorption, and carbohydrate oxidation during prolonged exercise468-475Journal of Applied Physiology72? (Rogers, J. Summers, R. W. Lambert, G. P.2005\Gastric emptying and intestinal absorption of a low-carbohydrate sport drink during exercise220-235@International Journal of Sport Nutrition and Exercise Metabolism153JunThe purpose of this study was to determine if lowering carbohydrate (CHO) concentration in a sport drink influences gastric emptying, intestinal absorption, or performance during cycle ergometry (85 min, 60% VO2peak). Five subjects (25 +/- 1 y, 61.5 +/- 2.1 mL center dot kg(-1) center dot min(-1) VO2peak) ingested a 3% CHO, 6% CHO, or a water placebo (WP) beverage during exercise. Gastric emptying was determined by repeated double sampling and intestinal absorption by segmental perfusion. Total solute absorption and plasma glucose was greater for 6% CHO; however, neither gastric emptying, intestinal water absorption, or 3-mi time trial performance (7.58 +/- 0.33 min, 8.13 +/- 0.25 min, and 8.25 +/- 0.29 min, respectively, for 6% CHO, 3% CHO, and WP) differed among solutions. These results indicate lowering the CHO concentration of a sport drink from 6% CHO does not enhance gastric emptying, intestinal water absorption, or time trial performance, but reduces CHO and total solute absorption.://000229765200003ISI:000229765200003 ?!MRyan, A. J. Lambert, G. P. Shi, X. Chang, R. T. Summers, R. W. Gisolfi, C. V.1998UEffect of hypohydration on gastric emptying and intestinal absorption during exercise 1581-1588Journal of Applied Physiology845MayiDehydration and hyperthermia may Impair gastric emptying (GE) during exercise; the effect of these alterations on intestinal water flux (WF) is unknown. Thus the purpose of this study was to determine the effect of hypohydration (similar to 2.7% body weight) on GE and WF of a water placebo (WP) during cycling exercise (85 min, 65% maximal oxygen uptake) in a cool environment (22 degrees C) and to also compare GE and WF of three carbohydrate-electrolyte solutions (CES) while the subjects were hypohydrated. GE and WF were determined simultaneously by a nasogastric tube placed in the gastric antrum and via a multilumen tube that spanned the duodenum and the first 25 cm of jejunum. Hypohydration was attained 12-16 h before experiments by low-intensity exercise in a hot (45 degrees C), humid (relative humidity 50%) environment. Seven healthy subjects (age 26.7 +/- 1.7 yr, maximal oxygen uptake 55.9 +/- 8.2 ml.kg(-1).min(-1)) ingested either WP or a 6% (330 mosmol), 8% (400 mosmol), or a 9% (590 mosmol) CES the morning following hypohydration. For comparison, subjects ingested WP after a euhydration protocol. Solutions (similar to 2.0 liters total) were ingested as a large bolus (4.6 ml/kg body wt) 5 min before exercise and as small serial feedings (2.3 ml/kg body wt) every 10 min of exercise. Average GE rates were not different among conditions (P > 0.05). Mean (+/-SE) values for WF were also similar (P > 0.05) for the euhydration (15.3 +/- 1.7 ml cm-l h-l) and hypohydration (18.3 +/- 2.6 ml.cm(-1) h-l) experiments. During exercise after hypohydration, water absorption was greater (P < 0.05) with ingestion of WP (18.3 +/- 2.6) and the 6% CES (16.5 +/- 3.7), compared with the 8% CES (6.9 +/- 1.5) and the 9% CES (1.8 +/- 1.7). Mean values for final core temperature (38.6 +/- 0.1 degrees C), heart rate (152 +/- 1 beats/min), and change in plasma volume (-5.7 +/- 0.7%) were similar among experimental trials. We conclude that I) hypohydration to similar to 3% body weight does not impair GE or fluid absorption during moderate exercise when ingesting WP, and 2) hyperosmolality (>400 mosmol) reduced WF in the proximal intestine.://000073500800015ISI:000073500800015?"JTakii, H Takii, N Y Kometani, T Nishimura, T Nakae, T Kuriki, T Fushiki, T2005VFluids containing a highly branched cyclic dextrin influence the gastric emptying rate314-319(International Journal of Sports Medicine26?#GWallis, G. A. Rowlands, D. S. Shaw, C. Jentjens, Rlpg Jeukendrup, A. E.2005MOxidation of combined ingestion of maltodextrins and fructose during exercise426-432+Medicine and Science in Sports and Exercise373MarPurpose: 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(-1). Methods: Eight trained Cyclists (VO2max: 64.1 +/- 3.1 mL(.)kg(.)min(-1)) 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(-1) of maltodextrin (MD), 1.2 g(.)min(-1) of maltodextrin + 0.6 g(.)min(-1) 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-13. Results: Peak exogenous carbohydrate oxidation (last 30 min of exercise) rates were similar to40% higher with combined MD+F ingestion compared with MD only ingestion (1.50 +/- 0.07 and 1.06 +/- 0.08 g(.)min(-1), 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(-1), 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 similar to1.5 g(.)min(-1), and this is markedly higher than oxidation rates from ingesting maltodextrin alone.://000227531700013ISI:000227531700013?$Satterthwaite, F W1946?An approximate distribution of estimates of variance components110-114Biometrics Bulletin2,stats, degrees of freedom, confidence limits?%Hopkins, W. G.2006qSample sizes for magnitude-based inferences about clinical, practical or mechanistic significance (Abstract 2746) S528-S529'Medicine & Science in Sports & Exercise385?&!Joseph, L du Berger, R Belisle, P1997MBayesian and mixed Bayesian/likelihood criteria for sample size determination769-781Statistics in Medicine16?' Julious, S A2004LTutorial in biostatistics: sample sizes for clinical trials with Normal data 1921-1986Statistics in Medicine23?(Batterham, A M Hopkins, W G2006-Making meaningful inferences about magnitudes50-57:International Journal of Sports Physiology and Performance1?)/Martin, J C Gardner, A S Barras, M Martin, D T2006NModeling sprint cycling using field-derived parameters and forward integration592-597 +Medicine and Science in Sports and Exercise38׿?*Brouns, F., Kovacs, E.1997Functional drinks for athletes414-421!Trends in Food Science Technology8Over the past few decades, numerous studies have been carried out to establish the optimal composition of drinks that are designed to rehydrate the body rapidly. These studies have led to the insight that drinks should contain carbohydrate (CHO) and sodium to stimulate fluid absorption and fluid retention. However, the CHO content as well as the osmolality of the drink should be relatively low. According to these findings, the composition criteria for rehydration drinks have quite a narrow range. Drinks that are designed to supply energy or substances that stimulate energy metabolism differ considerably in their composition. This review highlights the most relevant aspects. ahttp://www.sciencedirect.com/science/article/B6VHY-3WJDVXR-35/2/15daa2e01641cd8ef88d43968d2d9a92 #Trends in Food Science & Technology?+,Carter, J.M., Jeukendrup, A.E., Jones, D. A.2004JThe Effect of Carbohydrate Mouth Rinse on 1-h Cycle Time Trial Performance2107-11+Medicine and Science in Sports and Exercise36PURPOSE 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.?,Coombes, J.S., Hamilton, K.L.20009The effectiveness of commercially available sports drinks181-209Sports Medicine29F?- Coyle, E F1994EFluid and carbohydrate replacement during exercise: how much and why?Sports Science Exchange7?.Cunningham, J.J.1997LIs potassium needed in sports drinks for fluid replacement during exercise? 154-159AInternational Journal of Sports Nutrition and Exercise Metabolism7?/Gisolfi, C.V. Duchman, S.M.1992JGuidelines for optimal replacement beverages for different athletic events679-687+Medicine and Science in Sports and Exercise24,carbohydrate, fluid, endurance, electrolytesU?0QJentjens, Rlpg Underwood, K. Achten, J. Currell, K. Mann, C. H. Jeukendrup, A. E.2006Exogenous carbohydrate oxidation rates are elevated after combined ingestion of glucose and fructose during exercise in the heat807-816Journal of Applied Physiology100Mar://000235210200009CCC:000235210200009?1!Jentjens, R. L. Jeukendrup, A. E.2005High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose ingested during prolonged cycling exercise485-92British Journal of Nutrition93wA recent study from our laboratory has shown that a mixture of glucose and fructose ingested at a rate of 1.8 g/min leads to peak oxidation rates of approximately 1.3 g/min and results in approximately 55% higher exogenous carbohydrate (CHO) oxidation rates compared with the ingestion of an isocaloric amount of glucose. The aim of the present study was to investigate whether a mixture of glucose and fructose when ingested at a high rate (2.4 g/min) would lead to even higher exogenous CHO oxidation rates (>1.3 g/min). Eight trained male cyclists (VO2max: 68+/-1 ml/kg per min) cycled on three different occasions for 150 min at 50% of maximal power output (60+/-1% VO2max) and consumed either water (WAT) or a CHO solution providing 1.2 g/min glucose (GLU) or 1.2 g/min glucose+1.2 g/min fructose (GLU+FRUC). Peak exogenous CHO oxidation rates were higher (P<0.01) in the GLU+FRUC trial compared with the GLU trial (1.75 (SE 0.11) and 1.06 (SE 0.05) g/min, respectively). Furthermore, exogenous CHO oxidation rates during the last 90 min of exercise were approximately 50% higher (P<0.05) in GLU+FRUC compared with GLU (1.49 (SE 0.08) and 0.99 (SE 0.06) g/min, respectively). The results demonstrate that when a mixture of glucose and fructose is ingested at high rates (2.4 g/min) during 150 min of cycling exercise, exogenous CHO oxidation rates reach peak values of approximately 1.75 g/min.15946410Using Smart Source Parsing Aprӿ?2AJentjens, Roy L. P. G. Venables, Michelle C. Jeukendrup, Asker E.2004VOxidation of exogenous glucose, sucrose, and maltose during prolonged cycling exercise 1285-1291Journal of Applied Physiology96 April 1, 2004The purpose of the present study was to investigate whether combined ingestion of two carbohydrates (CHO) that are absorbed by different intestinal transport mechanisms would lead to exogenous CHO oxidation rates of >1.0 g/min. Nine trained male cyclists (maximal O2 consumption: 64 {+/-} 2 ml{middle dot}kg body wt-1{middle dot}min-1) performed four exercise trials, which were randomly assigned and separated by at least 1 wk. Each trial consisted of 150 min of cycling at 50% of maximal power output (60 {+/-} 1% maximal O2 consumption), while subjects received a solution providing either 1.8 g/min of glucose (Glu), 1.2 g/min of glucose + 0.6 g/min of sucrose (Glu+Suc), 1.2 g/min of glucose + 0.6 g/min of maltose (Glu+Mal), or water. Peak exogenous CHO oxidation rates were significantly higher (P < 0.05) in the Glu+Suc trial (1.25 {+/-} 0.07 g/min) compared with the Glu and Glu+Mal trials (1.06 {+/-} 0.08 and 1.06 {+/-} 0.06 g/min, respectively). No difference was found in (peak) exogenous CHO oxidation rates between Glu and Glu+Mal. These results demonstrate that, when a mixture of glucose and sucrose is ingested at high rates (1.8 g/min) during cycling exercise, exogenous CHO oxidation rates reach peak values of [~]1.25 g/min.8http://jap.physiology.org/cgi/content/abstract/96/4/1285J Appl Physiol?3)Maughan, R.J., Fenn, C. E., Leiper, J. B.1989KEffects of fluid, electrolyte and substrate ingestion on endurance capacity481-486&European Journal of Applied Physiology58??4 Noakes, T. D.19957Dehydration during exercise: what are the real dangers?123-8"Clinical Journal of Sport Medicine5The belief that dehydration poses significant health risks for endurance athletes, especially marathon and ultramarathon runners, stems from the classical 1969 study of Wyndham and Strydom entitled "The Danger of an Inadequate Water Intake During Marathon Running." The subsequent influence of the paper relates more to its incorrect title than to its scientific content. For the authors did not study nor did they identify any dangers resulting from an inadequate water intake during marathon running. In fact, the most dehydrated runners in their studies were also the most successful, as they won the competitive races that were studied. The positive result of the study was to influence international rule changes to allow increased fluid intake during competitive running races. The less desirable effect was to induce a dogmatic zeal among sports medicine practitioners who began to extol the dangers of dehydration during exercise. The (il)logic spurring this zeal seems to have been the conclusion that progressive dehydration during exercise will cause heatstroke, which is the most important cause of collapse during exercise. Hence, (i) heatstroke during running can only be avoided if dehydration is prevented, and (ii) all persons who collapse in association with exercise will have a heat disorder, which must be treated with intravenous fluid therapy.(ABSTRACT TRUNCATED AT 250 WORDS) [References: 50]7882113Using Smart Source Parsing{?5 Rehrer, N.J.20016Fluid and electrolyte balance in ultra-endurance sport701-715Sports Medicine31-Ư?6Sejersted, O.M.1992NElectrolyte imbalance in body fluids as a mechanism of fatigue during exercise149-205Energy Metabolism5Lamb, D.R. Gisolfi, C.V. Dubuque, IABrown and BenchmarkAcid-base, review, fatigue5Perspectives in exercise science and sports medicine.T?7MWallis, G.A., Rowlands, D.S., Shaw, C., Jentjens, R.L.P.G., Jeukendrup, A.E.,2005MOxidation of combined ingestion of maltodextrins and fructose during exercise426-432+Medicine and Science in Sports and Exercise37bThe purpose of the present study was to determine if 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-1. Eight trained cyclists (VO2max: 64.1±3.1 ml.kg.min-1) 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-1 of maltodextrin (MD), 1.2 g.min-1 of maltodextrin + 0.6 g.min-1 of fructose (MD+F) or plain water. In order to quantify exogenous carbohydrate oxidation, corn-derived MD and F were used, which have a high natural abundance of 13C. Peak exogenous carbohydrate oxidation rates were ~40% higher with combined MD+F ingestion compared with MD only ingestion (1.53±0.07 and 1.10±0.09 g.min-1 respectively, P<0.01). Furthermore, the average exogenous carbohydrate oxidation rate during the last 90 min of exercise was higher with combined MD+F ingestion compared to MD alone (1.38±0.06 and 0.96±0.07 g.min-1 respectively, P<0.01). 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 ~1.5 g.min-1, and this is markedly higher than oxidation rates from ingesting maltodextrin alone.?8&Rogers, M. S. Chang, A. M. Z. Todd, S.2005BUsing group-sequential analysis to achieve the optimal sample size529-533;BJOG An International Journal of Obstetrics and Gynaecology112?9 Hopkins, W G2006Magnitude matters58 Sportscience10.http://sportsci.org/2006/inbrief.htm#magnitude]Sport and Recreation, AUT University, Auckland 0627, New Zealand. Email: will=AT=clear.net.nzY?: Taubes, G.1995Epidemiology faces its limits164-169Science269?; Hopkins, W G2007mA spreadsheet for deriving a confidence interval, mechanistic inference and clinical inference from a p value16-20 Sportscience11jclinical decision, confidence limits, null-hypothesis test, practical importance, statistical significance#http://sportsci.org/2007/wghinf.htmZSport and Recreation, AUT University, Auckland 0627, New Zealand. Email: will@clear.net.nz?< Hopkins, W G2007mA spreadsheet for deriving a confidence interval, mechanistic inference and clinical inference from a p value16-20 Sportscience11jclinical decision, confidence limits, null-hypothesis test, practical importance, statistical significance#http://sportsci.org/2007/wghinf.htmZSport and Recreation, AUT University, Auckland 0627, New Zealand. 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