Caffeine intake improves muscular endurance and induces depletion of anaerobic work capacity in the bench press

Abstract Aim: To investigate the effects of caffeine (CAF) ingestion on anaerobic work capacity (AWC) and muscular endurance in the bench press exercise at predictive intensities equivalent to 20, 25, and 30% of 1RM. Methods: Thirteen males (age: 23 ± 3 years; body mass 83.5 ± 4.9 kg; height 172.8 ± 5.0 cm and 1RM 82 ± 24 kg) had their 1RM test evaluated in the bench press exercise and the time until failure was performed at intensities equivalent to 20%, 25%, and 30% of 1RM to CAF (350mg) or placebo (PLA, cellulose). AWC was measured from the linear equation: "Force = Critical Force + (AWC x 1/timeout)". Results: CAF enhanced the time until failure at 20% of 1RM (PLA = 202.6 ± 29.1s; CAF = 243.2 ± 20.6s), but there was no ergogenic effect at 25% (PLA = 188.8 ± 23.5 s; CAF = 195.6 ± 27.1 s), and 30% (PLA = 147.4 ± 15.8 s; CAF = 145.4 ± 14.8 s). AWC in CAF was lower than PLA (PLA = 6378.0 ± 1214.9 J; CAF = 3246.4 ± 1389.7 J; p = 0.03; Effect size = 0.88). Critical Force (N) was not different between treatments PLA 29.97 ± 11.54% of 1RM and CAF 3.74 ± 3.69% of 1 RM (p=0.47; Effect size= 0.28). Conclusion: Acute CAF intake (350mg) reduces the AWC and increases the time until failure at 20% of 1 RM, but not Critical Force and muscular endurance at 25% and 30% of 1 RM in the bench press.

Ingestion of a drink containing carbohydrate increases the number of bench press repetitions / A ingestão de uma bebida com carboidrato aumenta o número de repetições no exercício supino reto

ABSTRACT Objective The aim of this study was to analyze the effects of carbohydrate ingestion prior to exercise on the number of bench press repetitions. Methods Eight male physically active (21.3±2.7 years, 176±5cm, 73.12±6.12kg), with a minimum experience of at least one year exercising regularly, visited the laboratory at three moments. During the first visit, candidates went through their anthropometric evaluation and the application of their maximum number of bench press repetitions. The experimental tests were performed during their second and third visits in a crossover and blind study. The participants performed the maximum number of repetitions with an intensity of 70% of their maximum repetition strength. One hour before the experimental trials, participants randomly ingested a solution containing either carbohydrate or a placebo. Results The ingestion of carbohydrate increases muscle resistance in relation to placebo (p=0.014; effect size=0.71). This is evidenced by the increase in the number of repetitions (12.9±2.4 and 11.3±1.9, respectively). The individual's perception of effort is higher in the carbohydrate group than in the placebo group after exhaustion (4±0.93 and 3.1±0.64, respectively, p=0.006, effect size=0.89). Conclusion It is concluded that a previous intake of carbohydrate is useful in improving performance in resistance exercises, providing an increase in the individual's perception of effort.

RESUMO Objetivo O presente estudo teve como objetivo verificar os efeitos da ingestão prévia de carboidrato no número de repetições durante o exercício supino reto em indivíduos praticantes de musculação. Métodos Oito participantes fisicamente ativos do sexo masculino (21,3±2,7 anos, 176±5cm, 73,12±6,12kg) com experiência mínima de um ano em treinamento de força visitaram o laboratório em três momentos. Durante a primeira visita foi realizada uma avaliação antropométrica e aplicação do teste de uma repetição máxima no exercício supino reto. Os testes experimentais foram realizados nas visitas dois e três em um modelo cross over e cego onde os participantes executaram o número máximo de repetições com uma intensidade de 70% de uma repetição máxima. Uma hora antes dos testes experimentais, de forma randômica, os participantes ingeriram uma solução contendo carboidrato ou placebo. Resultados A ingestão de carboidrato foi capaz de aumentar a resistência muscular em relação ao placebo (p=0.014; effect size=0.71), fato evidenciado pelo aumento no número de repetições (12,9±2,4 e 11,3±1,9, respectivamente). A percepção subjetiva de esforço foi maior no grupo carboidrato em relação ao grupo placebo após a exaustão (4±0,93 e 3,1±0,64, respectivamente p=0.006, effect size=0.89). Conclusão Concluímos que a ingestão prévia de carboidrato é útil em melhorar o desempenho em exercícios de resistência com aumento associado da percepção subjetiva de esforço.

Carbohydrate mouth rinse reduces rating of perceived exertion but does not affect performance and energy systems contribution during a high-intensity exercise

Aim: The study aimed to verify the effect of carbohydrate (CHO) mouth rinse on time to exhaustion, energy systems contribution and rating of perceived exertion (RPE) during a high-intensity exercise. Methods Fourteen men performed an incremental exercise test to determine their maximal oxygen uptake and peak power output (PPO) and two time-to-exhaustion tests at 110% of PPO. Participants rinsed their mouth with 25ml of 6.4% of CHO or placebo (PLA) solution immediately before the time-to-exhaustion test, using a crossover design. The contribution of the energy systems was calculated using the free software GEDAE-LaB®. Results: Time to exhaustion was similar between the conditions (CHO:174.3±42.8s; PLA:166.7±26.3s; p=0.33). In addition, there was no difference between the CHO and PLA condition for aerobic (CHO:135.1±41.2kJ and PLA:129.8±35.3kJ, p=0.34), anaerobic lactic (CHO:57.6±17.1kJ and PLA:53.4±15.1kJ, p=0.10), and anaerobic alactic (CHO:10.4±8.4kJ and PLA:13.2±9.2kJ, p=0.37) contribution. Consequently, total energy expenditure was similar between conditions (CHO:203.2±46.4kJ and PLA:196.5±45.2kJ, p=0.15). However, CHO mouth rinse reduced the RPE at the moment of exhaustion (CHO:18.2±1.0units and PLA:19.1±1.1units; p=0.02). Conclusion: CHO mouth rinse neither increased time to exhaustion nor altered energy systems contribution during a high-intensity exercise, but reduced the perceived effort at the exhaustion.(AU)

Effects of carbohydrate intake on time to exhaustion and anaerobic contribution during supramaximal exercise / Efeito da ingestão de carboidrato sobre o tempo de exaustão e contribuição anaeróbia durante exercício supramáximo

ABSTRACT Objective: This study evaluated the effect of carbohydrate intake on time to exhaustion and anaerobic contribution during supramaximal exercise on a cycle ergometer. Methods: The sample comprised ten participants with a mean age of 23.9±2.5 years, mean body mass of 75.1±12.3 kg, mean height of 170.0±1.0 cm, and mean body fat of 11.3±5.2%. The participants underwent an incremental test to determine maximal oxygen uptake and maximum power output, and two supramaximal tests with a constant load of 110% of the maximum power output to exhaustion. Thirty minutes before the supramaximal tests the participants consumed carbohydrates (2 g.kg-1) or placebo. Results: The times to exhaustion of carbohydrate and placebo did not differ (carbohydrate: 170.7±44.6s; placebo: 156.1±26.7s, p=0.17; effect size=0.39). Similarly, the anaerobic contributions of the two treatments did not differ (carbohydrate: 3.0±0.9 L; placebo: 2.7±1.1 L, p=0.23; effect size=0.29). Conclusion: Carbohydrate intake was not capable of increasing time to exhaustion and anaerobic contribution in physically active men cycling at 110% of maximum power output.

RESUMO Objetivo: Este estudo foi conduzido com o intuito de verificar o efeito da ingestão de carboidrato sobre o tempo de exaustão e a contribuição anaeróbia durante o exercício supramáximo em uma bicicleta ergométrica. Métodos: Dez participantes fizeram parte da amostra (idade: 23,9±2,5 anos; massa corporal: 75,1±12,3 kg; estatura: 170,0±1,0 cm; gordura corporal: 11,3±5,2%). Todos realizaram um teste incremental para determinar o consumo máximo de oxigênio e a potência máxima e dois testes supramáximos com carga constante de 110% da potência máxima até a exaustão. Os participantes ingeriram carboidrato (2 g.kg-1) ou placebo 30 minutos antes dos testes supramáximos. Resultados: Não houve diferença significativa no tempo de exaustão entre carboidrato e placebo (carboidrato: 170,7±44,6s; placebo: 156,1±26,7s, p=0,17; effect size=0,39). De forma similar, não houve diferença significativa na contribuição anaeróbia entre as condições (carboidrato: 3,0±0,9 L; placebo: 2,7±1,1 L, p=0,23; effect size=0,29). Conclusão: A ingestão de carboidrato não foi capaz de aumentar o tempo até a exaustão e a contribuição anaeróbia em exercícios à 110% da potência máxima em homens fisicamente ativos.