Sex Differences in the Ergogenic Response of Acute Caffeine Intake on Muscular Strength, Power and Endurance Performance in Resistance-Trained Individuals: A Randomized Controlled Trial.

BACKGROUND: This study assessed the impact of acute caffeine intake on muscular strength, power, and endurance performance between resistance-trained male and female individuals according to load in upper- and lower-body exercises. METHODS: Here, 76 resistance-trained individuals (38 females, 38 males) participated in a study comparing caffeine and a placebo. Each received either 3 mg/kg of caffeine or a placebo 60 min before tests measuring muscular strength and power through bench press and back squat exercises at different intensities (25%, 50%, 75%, 90% 1RM). Muscular endurance at 65% 1RM was also assessed by performing reps until reaching task failure. RESULTS: Compared to placebo, caffeine increased mean, peak and time to reach peak velocity and power output (p < 0.01, ηp2 = 0.242-0.293) in the muscular strength/power test in males and females. This effect was particularly observed in the back squat exercise at 50%, 75% and 90% 1RM (2.5-8.5%, p < 0.05, g = 1.0-2.4). For muscular endurance, caffeine increased the number of repetitions, mean velocity and power output (p < 0.001, ηp2 = 0.177-0.255) in both sexes and exercises (3.0-8.9%, p < 0.05, g = 0.15-0.33). CONCLUSIONS: Acute caffeine intake resulted in a similar ergogenic effect on muscular strength, power, and endurance performance in upper- and lower-body exercises for male and female resistance-trained participants.

Effect of Acute Sodium Bicarbonate and Caffeine Coingestion on Repeated-Sprint Performance in Recreationally Trained Individuals: A Randomized Controlled Trial.

INTRODUCTION: The acute and isolated ingestion of sodium bicarbonate (NaHCO3) and caffeine (CAF) improves performance and delays fatigue in high-intensity tasks. However, it remains to be elucidated if the coingestion of both dietary supplements stimulates a summative ergogenic effect. This study aimed to examine the effect of the acute coingestion of NaHCO3 and CAF on repeated-sprint performance. METHODS: Twenty-five trained participants (age: 23.3 [4.0] y; sex [female/male]: 12/13; body mass: 69.6 [12.5] kg) participated in a randomized, double-blind, placebo (PLA) -controlled, crossover study. Participants were assigned to 4 conditions: (1) NaHCO3 + CAF, (2) NaHCO3, (3) CAF, or (4) PLA. Thus, they ingested 0.3 g/kg of NaHCO3, 3 mg/kg of CAF, or PLA. Then, participants performed 4 Wingate tests (Wt), consisting of a 30-second all-out sprint against an individualized resisted load, interspersed by a 1.5-minute rest period between sprints. RESULTS: Peak (Wpeak) and mean (Wmean) power output revealed a supplement and sprint interaction effect (P = .009 and P = .049, respectively). Compared with PLA, NaHCO3 + CAF and NaHCO3 increased Wpeak performance in Wt 3 (3%, P = .021) and Wt 4 (4.5%, P = .047), while NaHCO3 supplementation increased mean power performance in Wt 3 (4.2%, P = .001). In Wt 1, CAF increased Wpeak (3.2%, P = .054) and reduced time to Wpeak (-8.5%; P = .008). Plasma lactate showed a supplement plus sprint interaction (P < .001) when NaHCO3 was compared with CAF (13%, P = .031) and PLA (23%, P = .021). CONCLUSION: To summarize, although the isolated ingestion of CAF and NaHCO3 improved repeated-sprint performance, the coingestion of both supplements did not stimulate a synergic ergogenic effect.

Physical actions and work-rest time in men's beach volleyball / Ações físicas e intervalo trabalho-descanso em voleibol de praia masculino / Acciones físicas y tiempos de trabajo-descanso en voley-playa masculino

The purpose of this study was to assess the ball contacts, jumps, hits, work time, and rest ratio in male beach volleyball players in relation to their tactical roles. The sample of this study included 6970 rallies played by 91 beach volleyball players, which corresponded to 179 sets of the 2008 Men's Beach Volleyball World Tour (FIVB). We analyzed: ball contacts, jumps, hits, work time, rest time, set (first, second or third), and player's tactical role (e.g., defense specialist, blocker, or no specialization). A significantly higher number of jumps were executed by blockers. No differences were found in the third set for any of the physical variables studied. This paper provides references about the physical demands (e.g., contacts, jumps, and hits for blockers and defense specialists) and temporal patterns of the beach volleyball game (i.e., work and rest time) for two-set matches and three-set matches...

"Ações físicas e intervalo trabalho-descanso em voleibol de praia masculino." O objetivo do presente estudo foi avaliar o número de contatos com a bola, saltos, ataques, tempo de trabalho e descanso em jogadores de voleibol de praia masculino em função da sua especialização. A amostra do estudo foi composta por 6970 rallies, jogados por 91 participantes, correspondendo a 179 sets do Beach Volleyball World Tour (FIVB) de 2008. As variáveis estudadas foram: contatos com a bola, saltos, ataques, tempo de trabalho, tempo de descanso, set (1º, 2º e 3º) e especialização do jogador (defensor especialista, bloqueador, ou não especializado). Um número significativo de saltos foi realizado pelos bloqueadores. Não foram encontradas diferenças significativas no 3º set para qualquer uma das variáveis estudadas. Este estudo apresenta valores de referência acerca das demandas físicas (contatos, saltos e ataques realizados por bloqueadores e defensores especialistas) e dos padrões temporais do jogo de voleibol de praia (tempo de trabalho e descanso) para jogos de dois e três sets...

"Acciones físicas y tiempos de trabajo-descanso en voley-playa masculino." El objetivo de este estudio fue medir el número de contactos con el balón, saltos, golpeos, el tiempo de trabajo y de descanso de jugadores de voley-playa masculino en función de su rol de juego. La muestra de estudio estuvo compuesta por 6970 jugadas realizadas por 91 jugadores participantes en 179 sets de la Beach Volleyball World Tour (FIVB) de la temporada 2008. Las variables registradas fueron contactos realizadas, saltos, golpeos, tiempo trabajo, tiempo de descanso, set (1º, 2º, o 3º), and función de juego (bloqueador, especialista en defensa, o universal). Un significativo mayor número de saltos fueron realizados por los bloqueadores. No se encontraron diferencias en el tercer en ninguna de las variables físicas estudiadas. Este trabajo presenta valores de referencias de las demandas físicas (balón, saltos, golpeos) y parámetros temporales (tiempo de trabajo y de descanso) del juego del voley-playa para partidos de dos sets y de tres sets...