Caffeinated sports drink: ergogenic effects and possible mechanisms.
ABSTRACT This double-blind experiment examined the effects of a caffeinated sports drink during prolonged cycling in a warm environment. Sixteen highly trained cyclists completed 3 trials: placebo, carbohydrate-electrolyte sports drink (CES), and caffeinated sports drink (CES+CAF). Subjects cycled for 135 min, alternating between 60% and 75% VO2max every 15 min for the first 120 min, followed by a 15-min performance ride. Maximal voluntary (MVC) and electrically evoked contractile properties of the knee extensors were measured before and after cycling. Work completed during the performance ride was 15-23% greater for CES+CAF than for the other beverages. Ratings of perceived exertion were lower with CES+CAF than with placebo and CES. After cycling, the MVC strength loss was two-thirds less for CES+CAF than for the other beverages (5% vs. 15%). Data from the interpolated-twitch technique indicated that attenuated strength loss with CES+CAF was explained by reduced intrinsic muscle fatigue.
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ABSTRACT: Background Although energy drinks are known to have adverse effects, their consumption has increased markedly, especially among adolescents. Objective To explore the prevalence of consumption, pattern of use and knowledge about energy drinks among female secondary school students in Almadinah Almunawwarah, Kingdom of Saudi Arabia. Methods A cross-sectional survey of 600 female secondary school students was conducted with multi-stage sampling. Data were collected with an interview questionnaire. Frequencies, percentages and arithmetic means were calculated, and the chi-square test, ANOVA test and post hoc least significant difference were used with bivariate correlation. p Values <0.05 were considered significant. Results Most students (86.2%) did not recommend consumption of energy drinks; however, 52.2% drank them. Their popularity was attributed to advertising by 35.0%. They were drunk for vitality by 25.6% and to be alert by 20.8%. The active ingredients of energy drinks were not known by 69.6% of the students. Current energy drink use correlated with consumption by a family member or close friend. The type of drinks consumed correlated with degree of satisfaction, body changes, level of alertness and concentration obtained and withdrawal symptoms on cessation. Conclusion A health education intervention programme is needed to increase the awareness of students about the composition of energy drinks and their effects on health. Legislation is needed to ensure that the exact ingredients of these drinks are printed on the labels and to regulate use of these drinks by adolescents.Journal of Taibah University Medical Sciences. 04/2013; 8(1):60–65.
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ABSTRACT: Performance improvements after caffeine (CAF) ingestion are well documented when using a 1-d protocol. In numerous competitions such as the Tour de France, Tour de Ski, world championships, and National College Athletic Association championships, athletes compete for several days in a row. To date, no studies have investigated the effects of CAF when competing for consecutive days in a row. This study aimed to investigate the effects of placebo (PLA) and two different CAF doses (3 and 4.5 mg·kg body mass) on performance in a 10-min all-out, cross-country, double poling ergometer test (C-PT) 2 d in a row.Medicine and science in sports and exercise. 09/2014; 46(9):1787-1796.
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ABSTRACT: To determine the effects of co-ingesting caffeine (CAF) and carbohydrate (CHO) on high-intensity intermittent sprints (HIS) performance and physiological responses. Twelve active males underwent 4 interventions at least 7 days apart in a randomized, double-blind, placebo-controlled, balanced trial. A meal contained 65 % CHO was provided 2 h before the HIS test. Participants ingested the placebo (PLA) or CAF (6 mg kg(-1) BW) 1 h before taking an HIS test, and ingested a PLA or CHO solution (0.8 g kg(-1) BW) before undergoing the testing protocol. The HIS protocol comprised ten sets of 5 × 4-s sprints on a cycle ergometer with a 2-min recovery between each set. There was no significant difference between peak power output and mean power output between trials (p > 0.05). Compared with PLA, CAF + CHO resulted in a 5.2 % reduction in total work, corresponding to a 24.7-25.7 % increase in fatigue at the end stage of the HIS. The administration of CAF + CHO supplementation also resulted in an 11.1 % increase in blood lactate, and elevated blood glucose concentrations throughout HIS testing compared with PLA (p < 0.05). Cortisol concentrations also increased with CAF + CHO intake compared with PLA; however, there was no significant effect of CAF + CHO supplementation on testosterone concentrations. Co-ingestion of CAF and CHO did not improve high-intensity sprint cycling performance or reduce fatigue in active males. Moreover, combined CAF and CHO supplementation might facilitate catabolism during prolonged high-intensity intermittent exercise.Arbeitsphysiologie 04/2014; · 2.66 Impact Factor