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)

High-CHO diet increases post-exercise oxygen consumption after a supramaximal exercise bout

We investigated if carbohydrate (CHO) availability could affect the excess post-exercise oxygen consumption (EPOC) after a single supramaximal exercise bout. Five physically active men cycled at 115% of peak oxygen uptake (V̇O2 peak) until exhaustion with low or high pre-exercise CHO availability. The endogenous CHO stores were manipulated by performing a glycogen-depletion exercise protocol 48 h before the trial, followed by 48 h consuming either a low- (10% CHO) or a high-CHO (80% CHO) diet regime. Compared to the low-CHO diet, the high-CHO diet increased time to exhaustion (3.0±0.6 min vs 4.4±0.6, respectively, P=0.01) and the total O2 consumption during the exercise (6.9±0.9 L and 11.3±2.1, respectively, P=0.01). This was accompanied by a higher EPOC magnitude (4.6±1.8 L vs 6.2±2.8, respectively, P=0.03) and a greater total O2 consumption throughout the session (exercise+recovery: 11.5±2.5 L vs 17.5±4.2, respectively, P=0.01). These results suggest that a single bout of supramaximal exercise performed with high CHO availability increases both exercise and post-exercise energy expenditure.

Determinação do máximo déficit acumulado de oxigênio: efeito da duração dos testes submáximos para predição da demanda de oxigênio / Determination of the maximum accumulated oxygen deficit: effects of the submaximal tests duration for prediction of oxygen demand

O objetivo do presente estudo foi verificar a influência de diferentes tempos de análise dos testes submáximos para determinação do máximo déficit acumulado de oxigênio (MAOD), adotando diferentes janelas de tempo 4-6min, 6-8min e 8-10min. Participaram do estudo 10 ciclistas com idade média de 27,5 ± 4,1 anos, massa corporal 74,4 ± 12,7kg e tempo médio de prática de 9,8 ± 4,7 anos. Os atletas realizaram um teste de esforço progressivo para determinação do consumo de oxigênio de pico (VO2pico) e quatro testes retangulares submáximos (60, 70, 80 e 90 por cento VO2pico) com 10min de duração para estimar os valores da demanda de O2 (DEO2). Os valores médios de VO2 obtidos nas cargas para o tempo 4-6min, 6-8min e 8 a 10min foram aplicados em uma regressão linear entre a intensidade e o consumo de O2 para cada janela de tempo. Os sujeitos realizaram ainda um teste retangular supramáximo (110 por cento VO2pico) para a quantificação do MAOD. Não foi constatada nenhuma diferença significativa no VO2 entre os diferentes períodos de tempo dos testes submáximos (P > 0,05). Da mesma forma, nenhuma diferença significativa foi constatada no DEAO2 e MAOD nos diferentes períodos de análise (P > 0,05). Verificou-se ainda que os valores de MAOD obtidos nos três intervalos de tempo apresentaram boa concordância e forte correlação. Dessa forma, os dados sugerem que os testes submáximos utilizados para gerar os valores do MAOD podem ser reduzidos ao menos nesse tipo de amostra e com a utilização de ciclossimulador.

The aim of this study was to investigate the influence of different assessment time periods of submaximal tests on the determination of the maximal accumulated oxygen deficit (MAOD), through the adoption of different time slots of 4 to 6, 6 to 8 and 8 to 10 min. Ten cyclists with mean age of 27.5 ± 4.1 years, body mass 74.4 ± 12.7 kg and time experience of 9.8 ± 4.7 years participated in this study. The athletes underwent an incremental exercise test to determine the peak oxygen consumption (VO2peak), and four submaximal constant work-load test sessions (60, 70, 80 and 90 percent VO2peak) of 10 min in order to estimate the O2 demand (DEO2). The mean VO2 values obtained on each constant work-load for the 4 to 6, 6 to 8 and 8 to 10 min time-periods intervals were used to perform a linear regression between the intensity and O2 consumption for each time-period. In addition, the subjects performed one supramaximal rectangular test (110 percent VO2peak) for the quantification of MAOD. There was no significant difference in VO2 between the different time-periods for all submaximal tests (P> 0.05). Similarly, no significant difference was found in DEAO2 and MAOD (P> 0.05). Furthermore, the values of MAOD for the three time-periods intervals showed good agreement and strong correlation. Thus, the data suggest that the submaximal tests used to estimate the values of MAOD can be reduced, at least in this type of sample, and with the use of a cycle simulator.

Determinação visual do componente rápido do excesso do consumo de oxigênio após o exercício / Visual determination of the fast component of excessive oxygen uptake after exercise

O objetivo do presente estudo foi analisar a validade, a reprodutibilidade e a objetividade do método de inspeção visual durante a identificação da fase rápida do excesso do consumo de oxigênio após o exercício (EPOC RÁPIDO). Dez homens fisicamente ativos (idade de 23,0 ± 4,0 anos, estatura de 176,4 ± 6,8cm, massa corporal de 72,4 ± 8,2kg, VòO2max 3,0 ± 0,5L ? min-1) realizaram um teste incremental máximo e um teste de carga constante até a exaustão a 110 por cento da carga máxima obtida no teste incremental. O consumo de oxigênio foi mensurado respiração a respiração durante dez minutos de recuperação passiva após o teste de carga constante. O EPOC RÁPIDO foi determinado matematicamente e visualmente por três avaliadores. O método visual foi aplicado duas vezes nos três avaliadores para verificar a sua reprodutibilidade. Não foram detectadas diferenças significativas entre os valores do EPOC RÁPIDO estabelecidos pelo método matemático (0,98 ± 0,45L) e pelo método visual identificado pelos três avaliadores (1,04 ± 0,45L, 1,02 ± 0,45L e1,02 ± 0,45L). Nenhuma diferença foi encontrada entre a primeira e a segunda identificação feita pelos avaliadores (avaliador 1: 1,04 ± 0,45L vs 1,04 ± 0,49L; avaliador 2: 1,02 ± 0,45L vs 1,01 ± 0,44L e avaliador 3: 1,02 ± 0,45L vs1,03 ± 0,47L). Além disso, o coeficiente de correlação intraclasse entre as duas identificações foi alto para todos os avaliadores (ICC entre 0,97 e0,99). Esses resultados sugerem que a inspeção visual é um método válido, objetivo e reprodutivo para a estimativa do EPOC RÁPIDO.

The objective of this study was to analyze the validity, reproducibility and objectivity of the visual inspection method during the identification of the fast component of excess post-exercise oxygen consumption (EPOC FAST). Ten healthy physically active men (age = 23.0 + 4.0 years; height = 176.4 + 6.8 cm; body mass = 72.4 + 8.2 kg; VO2MAX = 3.0 + 0.5 L.min-1) performed a maximal incremental exercise and a constant workload test until exhaustion corresponding to 110 percent of maximal workload reached during the maximal incremental exercise. Oxygen consumption was measured breath-by-breath for 10 minutes during the passive recovery after the constant workload test. EPOC FAST was mathematically and visually determined by three evaluators. Double visual determination of EPOC FAST was carried out by each evaluator for reproducibility determination. There were no significant differences between EPOCFAST values obtained by mathematical (0.98 ± 0.45 L) or visual method (1.04 ± 0.45 L; 1.02 ± 0.45 L and 1.02 ± 0.45 L). None significant difference was found between the first and second visual assessment carried out by the evaluators (evaluator 1: 1.04 ± 0.45 L vs 1.04 ± 0.49 L; evaluator 2: 1.02 ± 0.45 L vs 1.01 ± 0.44 L and evaluator 3: 1.02 ± 0.45 L vs 1.03 ± 0.47 L). Finally, coefficient of intra-class correlation between determinations was high for all evaluators (ICC from 0.97 to 0.99). These results suggest that the visual method is valid, objective and reproducible for determination of the EPOC FAST.

THE RELATIVE CONTRIBUTION OF ANAEROBIC AND AEROBIC ENERGY SYSTEMS DURING FLAT-WATER KAYAK PADDLING / 体力科学

The purposes of this study were to investigate the characteristics of physiological responses during flat-water kayaking events, and to quantify the contribution of aerobic and anaerobic energy systems. Eight male kayak paddlers participated in the study. The subjects performed an incremental test and five all-out tests (20, 40, 120, 240 and 600 sec) on a kayak ergometer. Peak oxygen uptake (VO₂peak ; 3790 ml · min^-1) in the incremental test was significantly lower than maximal oxygen uptake (VO₂max ; 3944 ml · min^-1) in the all-out test. In contrast, power at VO₂peak (154.0 W) was significantly higher than power at VO₂max (144.1 W). The contributions of energy systems were calculated by measurements of the accumulated oxygen uptake and accumulated oxygen deficit. The relative anaerobic energy system contributions for 200 m(40 sec), 500 m (120 sec), and1000 m (240 sec) averaged 71%, 43%, and 26%, respectively. These higher relative anaerobic energy system contributions, due to higher anaerobic capacity in kayak athletes, and the smaller muscle mass involved in kayak paddling limit oxygen uptake when exercise intensity is high. Furthermore, slower exercise cadence in kayak paddling leads to higher muscular tension, and thus may enhance the limiting of oxygen uptake.

RELATIONSHIP BETWEEN FLAT-WATER KAYAK PERFORMANCE AND ENERGY SUPPLY CAPACITY / 体力科学

The purpose of this study was to investigate the relationship between 2-min kayak ergometer performance (KEP) and energy supply capacity. Seventeen (male : 9, female : 8) kayak paddlers completed a maximal incremental test to determine aerobic capacity{maximal oxygen uptake (VO_2max) and lactate threshold (LT)}, and a 2-min all-out test to measure performance and anaerobic capacity{maximal accumulated oxygen deficit (MAOD)}. In addition, total energy supply capacity was estimated by these variables [{(T-score of VO_2max+T-score of LT)/2+T-score of MAOD}/2]. Oxygen uptake and blood lactate concentrations were continuously measured during the incremental test and at the completion of both tests. These tests were conducted on an air-braked kayak ergometer. Unlike the previous research, no significant relationships were found between KEP and VO_2max and LT in either male or female. MAOD correlated with KEP in female (r=0.75, p<0.05), but not in male. On the other hand, there was a significant correlation between KEP and total energy supply capacity (r=0.89, p<0.05, both male and female). In conclusion, total energy supply capacity accounted for a large part of KEP. These results indicate that flat-water kayak paddlers need to develop both aerobic and anaerobic capacities.