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.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.
"Contrary to what was found in the present study, others (Geiß et al., 1994) have tested the effects of EDs on 10 male endurance athletes and reported longer cycling times to exhaustion after cycling for 60-min at 70% VO 2max on a cycle ergometer under the ED condition compared to two placebo beverages partially lacking the full-set of ingredients of an ED. Other endurance cycling experiments with cyclists have been conducted (Cureton et al., 2007; Ganio et al., 2010; Ivy et al., 2009) with similar results showing more accumulated work with ED. Nonetheless, another endurance study with male runners (Umaña-Alvarado & Moncada-Jiménez, 2005) found no significant differences in mean running times between ED and placebo conditions. "
[Show abstract][Hide abstract] ABSTRACT: To determine the acute effect of an energy drink (ED) on physical performance of professional female volleyball players. 19 females (age= 22.3±4.9 yr.; height= 171.8±9.4 cm; weight= 65.2±10.1 kg) participated in a randomized, crossover, double-blind study to measure grip strength, vertical jump and anaerobic power in 3 different sessions (ED, placebo [PL] or no beverage [CTL]). For each session, participants arrived in a fasted state, consumed a standardized breakfast meal, and 1 h later completed the 3 baseline performance tests without having ingested the beverage. After completing the pre measurements, the athletes drank 6 ml/kg of body weight of the ED or PL and in the CTL condition no beverage was consumed. Post-test measurements were taken 30 min after the ingestion of liquids. A 3x2 repeated measures ANOVA revealed no significant within session and measurement time interactions for each performance test. Regardless of the measurement time, right hand grip strength was significantly higher in the ED condition (34.6±0.9 kg) compared to PL (33.4±1.1 kg) and CTL (33.6±1.0 kg) (p < 0.05). Regardless of the beverage ingested, averaged right hand grip strength, taking into account all 3 testing conditions, increased from pre to post-testing (Pre = 33.8±0.9 kg vs. Post = 33.9±1.0 kg; p = 0.029), as did the averaged fatigue index, obtained from the anaerobic power test (Pre = 65.9±2.2% vs. Post = 68.7± 2.0%; p= 0.049). The acute ingestion of an ED did not improve physical performance of professional Costa Rican female volleyball players.
Full-text · Article · Nov 2014 · International journal of sport nutrition and exercise metabolism
"Several studies have shown that an intake of 3 to 6 mg caffeine per kg bodymass or 450 mg improves performance of athletes especially in endurance exercise     without risking dehydration or imbalance of the electrolyte household  . "
[Show abstract][Hide abstract] ABSTRACT: Background: In contrast to caffeine bars, the effect of caffeine intake from tablets and energy drinks on endurance performance has already been investigated. Therefore, the aim of the study is to examine the effects of caffeine bars used as pre-exercise supplements on endurance performance in cycling. Methods: The present study was designed as a randomized single-blind cross-over placebo-controlled trial. Nine male, trained cyclists completed endurance exercises on a cycling ergometer under the following conditions: ingestion of water (WAT), placebo bars (PLA) and caffeine bars (CAF; 5 mg caffeine/kg bodyweight), respectively, 45 min prior to the test. After 40 min at a constant intensity of 75% VO 2 max (assessed in a previously performed incremental test) load was increased 10 W/min until exhaustion. Results: CAF compared to PLA resulted in a higher maximal power and longer time to exhaustion (p = .002). Surprisingly, concentration of free fatty acids was lower at exhaustion (p = .004), whereas blood lactate levels (p = .021) and heart rate (p = .008) were significantly higher after CAF. Subjects also reported lower received perception of effort at warm-up (0.034), 30 min (p = .026) and 40 min (p = .041) only after CAF. Conclusions: Caffeine bars are useful pre-exercise supplements. Their performance enhancing effect was rather due to a delayed perception of fatigue than an increased lipolysis, proving caffeine as central nervous system stimulant.
". Similar results were found in trained cyclists at extended bouts of exercise (120 minutes) at intensities ranging between 60% and 75% VO 2 max  . The effects of caffeine on athletic performance have been demonstrated with a variety of aerobic activities, including 1-km time trials on a track , rowing  , and swimming  . "
[Show abstract][Hide abstract] ABSTRACT: Caffeine is a commonly used stimulant thought to have ergogenic properties. Most studies on the ergogenic effects of caffeine have been conducted in athletes. The purpose of this study was to test the hypothesis that caffeine reduces ratings of perceived exertion and increases liking of physical activity in sedentary adults. Participants completed treadmill walking at 60% to 70% of their maximal heart rate at baseline and for 6 subsequent visits, during which half of the participants were given caffeine (3 mg/kg) and half given placebo in a sports drink vehicle. To investigate the potential synergistic effects of acute and chronic caffeine on self-determined exercise duration, participants were rerandomized to either the same or different condition for the last visit, creating 4 chronic/acute treatment groups (placebo/placebo, placebo/caffeine, caffeine/placebo, caffeine/caffeine). Participants rated how much they liked the activity and perceived exertion at each visit. There was a main effect of time on liking of physical activity, with liking increasing over time and an interaction of sex and caffeine treatment on liking, with liking of activity increasing in female participants treated with caffeine, but not with placebo. There was no effect of caffeine on ratings of perceived exertion. Individuals who received caffeine on the final test day exercised for significantly longer than those who received placebo. These data suggest that repeated exposure to physical activity significantly increases liking of exercise and reduces ratings of perceived exertion and that caffeine does little to further modify these effects.
No preview · Article · Jun 2013 · Nutrition research