The 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 · kg−1 · 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.
Jennifer Rogers, Robert W. Summers and G. Patrick Lambert
Iulian B. Dragusin and Craig A. Horswill
Sports drinks have been implicated in contributing to obesity and chronic diseases by providing surplus calories and excess sugars. Using existing literature we compared energy intake from sports drinks consumed during exercise with the exercise-induced calorie expenditure to determine whether sports drink use might eliminate the energy deficit and jeopardize conditions for improved metabolic fitness. We identified 11 published studies that compared sport drink consumption to placebo during exercise with a primary focused on the effect of sport drinks or total carbohydrate content on enhancing physical performance. Energy expenditure (EE) was calculated using VO2, RER, and exercise duration for the exercise protocol. Energy ingestion (EI) was determined using the carbohydrate dosing regimen administered before and during the exercise protocol. A two-tailed t test was used to test whether the energy balance (EI-EE) was different from zero (alpha level = 0.05). Sport drink consumption during aerobic exercise of sufficient duration (≥ 60 min) did not abolish the energy deficit (p < .001). Mean ± SD were EE, 1600 ± 639 Cal; EI, 394 ± 289 Cal; and EI-EE,-1206+594 Cal; VO2, 3.05 ± 0.55 L/min; RER, 0.91 ± 0.04; exercise duration 110 ± 42 min. Ingesting sports drinks to enhance performance did not abolish the caloric deficit of aerobic exercise. Sports drinks can be used in accordance with research protocols that typically provide 30–60 g of carbohydrate per hour when exercising at adequate durations for moderate to high intensity and still maintain a substantive caloric deficit.
Beau Kjerulf Greer, John L. Woodard, Jim P. White, Eric M. Arguello and Emily M. Haymes
The purpose of this study was to determine whether branched-chain amino acid (BCAA) supplementation attenuates indirect indicators of muscle damage during endurance exercise as compared with an isocaloric, carbohydrate (CHO) beverage or a noncaloric placebo (PLAC) beverage. Nine untrained men performed three 90-min cycling bouts at 55% VO2peak. Subjects, blinded to beverage selection, ingested a total of 200 kcal of energy via the CHO or BCAA beverage before and at 60 min of exercise, or they drank the PLAC beverage. Creatine kinase (CK), lactate dehydrogenase (LDH), isokinetic leg-extension and fexion torque, and muscle soreness were assessed before and immediately, 4 h, 24 h, and 48 h post exercise. The trials were separated by 8 wk. CK activities were significantly lower after the BCAA trial than in the PLAC trial at 4, 24, and 48 h post exercise, as well as lower than the CHO beverage at 24 h post exercise. CK was lower in the CHO trial at the 24- and 48-h time points than in the PLAC trial. LDH activities were lower in the BCAA trial at 4 h than in the PLAC trial. As compared with the CHO and PLAC trials, ratings of perceived soreness were lower at 24 h post exercise, and leg-fexion torque was higher at the 48-h time point after the BCAA trial. The present data suggest that BCAA supplementation attenuates muscle damage during prolonged endurance exercise in untrained college-age men. CHO ingestion attenuates CK activities at 24 and 48 h post exercise as compared with a placebo beverage.
Fred Brouns, Wim Saris and Heinz Schneider
The addition of carbohydrate and sodium to sport drinks has been recommended to enhance fluid intake and absorption and to delay fatigue. Other electrolytes (E) which are lost through sweating are also commonly added. However, too many E may lead to increased serum E and osmolality levels, which may negatively influence thermoregulation, depress sweating, and cause gastrointestinal distress. On the other hand, drinking large amounts of plain water to compensate sweat loss may induce hyponatremia. Therefore, literature describing sweat E losses was examined in order to estimate average whole-body E loss and to determine an upper limit for replacement of E with sport drinks. Mean E loss was determined from 13 studies, with +1 SD resulting in a hypothetical range for E losses. Correction for net absorption resulted in an upper limit of electrolyte replacement. It is suggested that the E levels in sport rehydration drinks should not exceed the upper limit of the range given.
Hans Braun, Karsten Koehler, Hans Geyer, Jens Kleinert, Joachim Mester and Wilhelm Schänzer
Little is known about the prevalence and motives of supplement use among elite young athletes who compete on national and international levels. Therefore, the current survey was performed to assess information regarding the past and present use of dietary supplements among 164 elite young athletes (16.6 ± 3.0 years of age). A 5-page questionnaire was designed to assess their past and present (last 4 weeks) use of vitamins, minerals, carbohydrate, protein, and fat supplements; sport drinks; and other ergogenic aids. Furthermore, information about motives, sources of advice, supplement sources, and supplement contamination was assessed. Eighty percent of all athletes reported using at least 1 supplement, and the prevalence of use was significantly higher in older athletes (p < .05). Among supplement users, minerals, vitamins, sport drinks, energy drinks, and carbohydrates were most frequently consumed. Only a minority of the athletes declared that they used protein/amino acids, creatine, or other ergogenic aids. Major motives for supplement use were health related, whereas performance enhancement and recommendations by others were less frequently reported. Supplements were mainly obtained from parents or by athletes themselves and were mostly purchased in pharmacies, supermarkets, and health-food stores. Among all athletes, only 36% were aware of the problem of supplement contamination. The survey shows that supplement use is common and widespread among German elite young athletes. This stands in strong contrast to recommendations by leading sport organizations against supplement use by underage athletes.
Jeffrey J. Zachwieja, David L. Costill, Jeffrey J. Widrick, Dawn E. Anderson and Glenn K. McConell
The intent of this study was to determine whether adding carbonation to either water or a low calorie sport drink would affect gastric emptying (GE). Fifteen subjects rode for 20 minutes on a cycle ergometer at 55% of max
Jeffrey J. Zachwieja, David L. Costill, Glenn C. Beard, Robert A. Robergs, David D. Pascoe and Dawn E. Anderson
To determine the effect of a carbonated carbohydrate (CHO) drink on gastric function and exercise performance, eight male cyclists completed four 120- min bouts of cycling. Each bout consisted of a 105-min ride at 70%
Matthew S. Hickey, David L. Costill and Scott W. Trappe
This study investigated the influence of drink carbonation and carbohydrate content on ad libitum drinking behavior and body fluid and electrolyte responses during prolonged exercise in the heat. Eight competitive male runners completed three 2-hr treadmill runs at 60%
Fran Longstaff, Nick Heather, Susan Allsop, Elizabeth Partington, Mark Jankowski, Helen Wareham, A. St Clair Gibson and Sarah Partington
This study examined whether students engaged in university sport have different drinking outcome expectancies and normative beliefs than students who are not engaged in university sport. A cross-sectional survey of university students in England in 2008–2009 was undertaken. A questionnaire battery, including the Drinking Expectancies Questionnaire (DEQ) and a measure of normative beliefs, was completed by 770 students from seven universities across England. Responses from 638 students who were not abstaining from alcohol were analyzed. Students engaged in university sport have significantly higher drinking expectancies of assertion compared with students not engaged in university sport. Moreover, students engaged in university sport consistently report higher personal alcohol consumption and higher perceptions of consumption in those around them than students not engaged in university sport. Both assertion and the perception that students around them drink heavily provide only a partial explanation for why students engaged in university sport drink more than those not engaged in university sport. Further research is required to identify the reasons for heavy drinking among students involved in university sport in England.
Ina Garthe and Ronald J. Maughan
supplements; past 6 Months Overall: 88 Increase energy (54%); health maintenance/prevent nutritional deficiency (54%); improve recovery (52%) Sport drinks: 22 Sport bars: 14 Multivitamins and minerals: 14 Protein supplements: 9 Vitamin C: 6 Karimian & Esfahani ( 2011 ) • 250 M & 250 F • Bodybuilders, Iran