Juan Del Coso, Alberto Pérez-López, Javier Abian-Vicen, Juan Jose Salinero, Beatriz Lara and David Valadés
There are no scientific data about the effects of caffeine intake on volleyball performance. The aim of this study was to investigate the effect of a caffeine-containing energy drink to enhance physical performance in male volleyball players. A double-blind, placebo-controlled, randomized experimental design was used. In 2 different sessions separated by 1 wk, 15 college volleyball players ingested 3 mg of caffeine per kg of body mass in the form of an energy drink or the same drink without caffeine (placebo). After 60 min, participants performed volleyball-specific tests: standing spike test, maximal squat jump (SJ), maximal countermovement jump (CMJ), 15-s rebound jump test (15RJ), and agility T-test. Later, a simulated volleyball match was played and recorded. In comparison with the placebo drink, the ingestion of the caffeinated energy drink increased ball velocity in the spike test (73 ± 9 vs 75 ± 10 km/h, P < .05) and the mean jump height in SJ (31.1 ± 4.3 vs 32.7 ± 4.2 cm, P < .05), CMJ (35.9 ± 4.6 vs 37.7 ± 4.4 cm, P < .05), and 15RJ (29.0 ± 4.0 vs 30.5 ± 4.6 cm, P < .05). The time to complete the agility test was significantly reduced with the caffeinated energy drink (10.8 ± 0.7 vs 10.3 ± 0.4 s, P < .05). In addition, players performed successful volleyball actions more frequently (24.6% ± 14.3% vs 34.3% ± 16.5%, P < .05) with the ingestion of the caffeinated energy drink than with the placebo drink during the simulated game. A caffeine-containing energy drink, with a dose equivalent to 3 mg of caffeine per kg body mass, might be an effective ergogenic aid to improve physical performance and accuracy in male volleyball players.
Alejandro Muñoz, Álvaro López-Samanes, Alberto Pérez-López, Millán Aguilar-Navarro, Berta Moreno-Heredero, Jesús Rivilla-García, Pablo González-Frutos, José Pino-Ortega, Esther Morencos and Juan Del Coso
Purpose: To investigate the effects of acute caffeine (CAFF) intake on physical performance in elite women handball players. Methods: A total of 15 elite women handball players participated in a randomized, double-blind study. In 2 different trials, participants ingested either a placebo (cellulose) or 3 mg of CAFF per kilogram of body mass (mg/kg bm) before undergoing a battery of neuromuscular tests consisting of handball throws, an isometric handgrip strength test, a countermovement jump, a 30-m sprint test (SV) and a modified version of the agility T test. Then, participants performed a simulated handball game (2 × 20 min), and movement patterns were recorded with a local positioning system. Results: Compared with the placebo, CAFF increased ball velocity in all ball throws (P = .021–.044; effect size [ES] = 0.39–0.49), strength in isometric handgrip strength test (350.8 [41.2] vs 361.6 [46.1] N, P = .034; ES = 0.35), and countermovement-jump height (28.5 [5.5] vs 29.8 [5.5] cm; P = .006; ES = 0.22). In addition, CAFF decreased running time in the SV (4.9 [0.2] vs 4.8 [0.3] s; P = .042; ES = −0.34). In the simulated game, CAFF increased the frequency of accelerations (18.1 [1.2] vs 18.8 [1.0] number/min; P = .044; ES = 0.54), decelerations (18.0 [1.2] vs 18.7 [1.0] number/min; P = .032; ES = 0.56), and body impacts (20  vs 22  impacts/min; P = .032; ES = 0.30). However, postexercise surveys about self-reported feelings of performance indicate that players did not feel increased performance with CAFF. Conclusion: Preexercise ingestion of 3 mg/kg bm of CAFF improved ball-throwing velocity, jump, and sprint performance and the frequency of in-game accelerations and decelerations in elite women handball players.
the findings that the immediate adverse effects of negative publicity might be alleviated over time, managers may want to limit the efforts or resources spent specifically on preventing the circulation of negative publicity. Instead, managers may focus more on ongoing and positive publicity efforts
Ryan D. Henke, Savana M. Kettner, Stephanie M. Jensen, Augustus C.K. Greife and Christopher J. Durall
find a significant between-group difference in days to recovery, although this study appears to have been underpowered. • Notably, there were no reports of adverse effects with LIAEX in any of the reviewed studies. Clinical Bottom Line Regarding the posed clinical question, evidence from 1 level 1b RCT
Ina Garthe and Ronald J. Maughan
manufacturers and distributors are not required to obtain approval from the FDA before marketing dietary supplements. This creates a substantial potential risk to the health of the public, and serious adverse effects have been reported from some dietary supplements that are currently being marketed ( FDA, 2017
Tanya Prewitt-White, Christopher P. Connolly, Yuri Feito, Alexandra Bladek, Sarah Forsythe, Logan Hamel and Mary Ryan McChesney
, & Hickey, 2013 ; Weisenthal, Beck, Maloney, DeHaven, & Giordano, 2014 ). Despite these negative connotations, there are multiple anecdotal accounts of pregnant women participating in this form of vigorous-intensity training without any adverse effects. In addition, Brown, Finch, Robinson, Torode, and
Peter W.R. Lemon
This paper reviews the factors (exercise intensity, carbohydrate availability, exercise type, energy balance, gender, exercise training, age, and timing of nutrient intake or subsequent exercise sessions) thought to influence protein need. Although there remains some debate, recent evidence suggests that dietary protein need increases with rigorous physical exercise. Those involved in strength training might need to consume as much as 1.6 to 1.7 g protein ⋅ kg−1 day−1 (approximately twice the current RDA) while those undergoing endurance training might need about 1.2 to 1.4 g ⋅ kg−1 day−1 (approximately 1.5 times the current RDA). Future longitudinal studies are needed to confirm these recommendations and assess whether these protein intakes can enhance exercise performance. Despite the frequently expressed concern about adverse effects of high protein intake, there is no evidence that protein intakes in the range suggested will have adverse effects in healthy individuals.
Bottom W. Brewer, Judy L. Van Raalte and Darwyn E. Linder
The effects of experimentally induced pressure pain on the performance of a weight lifting task, a simple golf putting task, and a complex golf putting task were examined in male college students. It was found that pain did not affect performance of the weight lifting task, slightly hampered performance of the simple putting task, and severely hampered performance of the complex putting task. Because the adverse effects of pain increased with task complexity, the findings are consistent with the notion mat pain is a form of arousal and mat pain affects performance in a manner similar to arousal. Limitations of the present experiments and directions for future research are discussed.
Daniel S. Kirschenbaum, David A. Wittrock, Robert J. Smith and William Monson
We propose that training athletes to use certain cognitive-behavioral procedures, “criticism inoculation training” (CIT), could enable them to circumvent the adverse effects of excessively negativistic coaching. This experiment evaluated the efficacy of one potential CIT strategy, positive self-monitoring (systematically observing and recording instances of success). A laboratory paradigm was used in which 60 male college students attempted to learn the underhand free throw basketball technique from one of four undergraduate pseudocoaches. Subjects were randomly assigned to four groups determined by a 2 (negative vs. no feedback) × 2 (positive vs. no self-monitoring) factorial design. Negative feedback was expected to debilitate, while positive self-monitoring was expected to facilitate performance, sustained self-observation of videotapes of performance, and subjective evaluations of the “coach” and the technique. Negative feedback clearly produced extensive adverse effects, but surprisingly, positive self-monitoring also decreased performance. Theories of skilled motor behavior (MacKay, 1982) and self-regulation (Carver, 1979) helped explain why positive self-monitoring failed as a CIT procedure. This interpretation which focuses on the novelty of the task and the development of negative expectancies also led to suggestions of strategies that could more effectively fulfill the promise of the CIT concept.