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A relação entre a alcalose metabólica e o desempenho esportivo tem sido investigada através de anipulações do pH sanguíneo. Entre as formas de manipulação do pH, o bicarbonato de sódio (NaHCO3) é o componente químico mais utilizado quando se pretende induzir um estado de alcalose sanguínea previamente ao exercício. Embora os benefícios do NaHCO3 no desempenho tenham sido amplamente demonstrados em exercícios intermitentes de alta intensidade, não há um consenso na literatura e pouco ainda é conhecido quanto aos efeitos do NaHCO3 em exercícios contínuos de ciclismo de alta intensidade. Nesse sentido, foram abordados na presente revisão os principais aspectos envolvidos na ingestão aguda e crônica de NaHCO3, enfatizando os mecanismos de ação dessa substância, especificações acerca da dose utilizada e seus efeitos sobre o desempenho em ciclismo de alta intensidade. Os resultados dos estudos apresentados na presente revisão revelam que a ingestão aguda de 0,3 g∙kg-1 de massa corporal (MC) de NaHCO3 é eficaz em melhorar o desempenho em eventos de alta intensidade se consumido em torno de 90 minutos antes do exercício. Para a ingestão crônica, uma dose de 0,5 g∙kg-1 ∙dia1 de MC durante 5-6 dias seria benéfica para o exercício de alta intensidade. Esses seriam os limites em ambos os protocolos para induzir um estado de alcalose metabólica e posteriormente melhorar o desempenho sem promover ou atenuando qualquer sintoma relacionado à sensações de desconforto gastrointestinal. Dessa forma, ambas as formas de ingestão de NaHCO3, aguda e/ou crônica, parecem melhorar o desempenho durante o ciclismo de alta intensidade realizados de modo contínuo, enfatizando a importância da suplementação de NaHCO3 como um recurso ergogênico. Porém, pesquisas adicionais utilizando protocolos de ingestão crônica e testando seus efeitos sobre o desempenho em provas mais prolongadas são requeridas devido ao reduzido número de investigações e o potencial efeito ergogênico dessa substância...(AU)

The relationship between metabolic alkalosis and exercise performance has been investigated through manipulation of the blood and muscle pH. Among the forms of pH manipulation, the sodium bicarbonate (NaHCO3) is the most used chemical component when is intentioned to induce a blood alkalosis state prior to exercise. While the benefits of NaHCO3 in performance have been widely demonstrated in high-intensity intermittent exercise, there is no consensus in the literature and little is known about the effects of NaHCO3 in continuous high-intensity cycling exercise. Thus, it was addressed in this present review the main aspects involved in acute and chronic NaHCO3 ingestion, giving a focus to the action mechanisms of this substance, specifications about the used dose and their effects on highintensity cycling performance. The results of the present review show that acute ingestion of 0.3 g∙kg-1 of body mass (BM) of NaHCO3 is effective in improving performance in high-intensity events if this substance is consumed in about 90 minutes prior to exercise. For chronic ingestion, a dose of 0.5 g∙kg1 ∙day-1 BM during 5-6 days should be beneficial for the high-intensity exercise. For both protocols these would be the limits to induce a metabolic alkalosis state and further improve the performance without promoting or attenuating any symptoms related to the gastrointestinal discomfort sensations. Thus, both acute and/or chronic NaHCO3 ingestion seem to improve performance during high-intensity cycling performed in a continuous mode, emphasizing the importance of NaHCO3 supplementation as an ergogenic aid. However, further research using chronic ingestion of protocols and testing their effects on performance in more prolonged tests are required due to the small number of studies and the potential ergogenic effect of this substance...(AU)

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The aim of this study was to investigate the effects of caffeine on reaction time during a specific taekwondo task and athletic performance during a simulated taekwondo contest. Ten taekwondo athletes ingested either 5 mg·kg⁻¹ body mass caffeine or placebo and performed two combats (spaced apart by 20 min). The reaction-time test (five kicks "Bandal Tchagui") was performed immediately prior to the first combat and immediately after the first and second combats. Caffeine improved reaction time (from 0.42 ± 0.05 to 0.37 ± 0.07 s) only prior to the first combat (P = 0.004). During the first combat, break times during the first two rounds were shorter in caffeine ingestion, followed by higher plasma lactate concentrations compared with placebo (P = 0.029 and 0.014, respectively). During the second combat, skipping-time was reduced, and relative attack times and attack/skipping ratio was increased following ingestion of caffeine during the first two rounds (all P < 0.05). Caffeine resulted in no change in combat intensity parameters between the first and second combat (all P > 0.05), but combat intensity was decreased following placebo (all P < 0.05). In conclusion, caffeine reduced reaction time in non-fatigued conditions and delayed fatigue during successive taekwondo combats.

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The aim of this study was to analyze the changes on repeated-sprint ability (RSA) performance after heavy load exercise in elite handball players. Twelve subjects were submitted to the following experimental sessions: (a) 1-repetition maximum (1RM) test on the half squat exercise, (b) RSA test (control condition), and (c) RSA with a conditioning activity on the same exercise as 1RM test (experimental condition). The conditioning activity comprised 1 set of 5 × 50% 1RM, 1 set of 3 × 70% 1RM, and 5 sets of 1 × 90% 1RM. A significant improvement in the best sprint time (RSAbest) and mean sprint time (RSAmean) was observed with the conditioning activity (RSAbest = 5.74 ± 0.16 seconds; RSAmean = 5.99 ± 0.19 seconds) when compared with the situation without the conditioning activity (RSAbest = 5.82 ± 0.15 seconds; RSAmean = 6.06 ± 0.18 seconds; p < 0.01) with a moderate (Cohen's d = -0.54) and small effect (Cohen's d = -0.41) to RSAbest and RSAmean, respectively. Therefore, the findings of this study demonstrated that prior heavy load exercise can be used to improve the RSA performance, however, with a small to moderate magnitude of change.

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The aim of this study was to develop an indoor rock-climbing test on an artificial wall (Fit-climbing test). Thirteen climbers (elite group [EG] = 6; recreational group [RG] = 7) performed the following tests: (a) familiarization in the Fit-climbing test, (b) the Fit-climbing test, and (c) a retest to evaluate the Fit-climbing test's reliability. Gas exchange, blood lactate concentration, handgrip strength, and heart rate were measured during the test. Oxygen uptake during the Fit-climbing test was not different between groups (EG = 8.4 ± 1.1 L; RG = 7.9 ± 1.5 L, p > 0.05). The EG performance (120 ± 7 movements) was statistically higher than the RG climbers' performance (78 ± 13 movements) during the Fit-climbing test. Consequently, the oxygen cost per movement during the Fit-climbing test of the EG was significantly lower than that of the RG (p < 0.05). Handgrip strength was higher in the EG when compared with that in the RG in both pre-Fit- and post-Fit-climbing test (p < 0.05). There were no significant differences in any other variables analyzed during the Fit-climbing test (p > 0.05). Furthermore, the performance in the Fit-climbing test presented high reliability (intraclass correlation coefficient = 0.97). Therefore, the performance during the Fit-climbing test may be an alternative to evaluate rock climbers because of its specificity and relation to oxygen cost per movement during climbing.

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The purpose of this study was to investigate the main bioenergetics and neuromuscular determinants of the time to exhaustion (T(lim)) at the velocity corresponding to maximal oxygen uptake in recreational long-distance runners. Twenty runners performed the following tests on 5 different days: (a) maximal incremental treadmill test, (b) 2 submaximal tests to determine running economy and vertical stiffness, (c) exhaustive test to measured the T(lim), (d) maximum dynamic strength test, and (e) muscle power production test. Aerobic and anaerobic energy contributions during the T(lim) test were also estimated. The stepwise multiple regression method selected 3 independent variables to explain T(lim) variance. Total energy production explained 84.1% of the shared variance (p = 0.001), whereas peak oxygen uptake (V(O2)peak) measured during T(lim)and lower limb muscle power ability accounted for the additional 10% of the shared variance (p = 0.014). These data suggest that the total energy production, V(O2)peak, and lower limb muscle power ability are the main physiological and neuromuscular determinants of T(lim)in recreational long-distance runners.

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The aim of this study was to examine the influence of the performance level of athletes on pacing strategy during a simulated 10-km running race, and the relationship between physiological variables and pacing strategy. Twenty-four male runners performed an incremental exercise test on a treadmill, three 6-min bouts of running at 9, 12 and 15 km h(-1), and a self-paced, 10-km running performance trial; at least 48 h separated each test. Based on 10-km running performance, subjects were divided into terziles, with the lower terzile designated the low-performing (LP) and the upper terzile designated the high-performing (HP) group. For the HP group, the velocity peaked at 18.8 +/- 1.4 km h(-1) in the first 400 m and was higher than the average race velocity (P < 0.05). The velocity then decreased gradually until 2,000 m (P < 0.05), remaining constant until 9,600 m, when it increased again (P < 0.05). The LP group ran the first 400 m at a significantly lower velocity than the HP group (15.6 +/- 1.6 km h(-1); P > 0.05) and this initial velocity was not different from LP average racing velocity (14.5 +/- 0.7 km h(-1)). The velocity then decreased non-significantly until 9,600 m (P > 0.05), followed by an increase at the end (P < 0.05). The peak treadmill running velocity (PV), running economy (RE), lactate threshold (LT) and net blood lactate accumulation at 15 km h(-1) were significantly correlated with the start, middle, last and average velocities during the 10-km race. These results demonstrate that high and low performance runners adopt different pacing strategies during a 10-km race. Furthermore, it appears that important determinants of the chosen pacing strategy include PV, LT and RE.

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The objective of the present study was to verify if active recovery (AR) applied after a judo match resulted in a better performance when compared to passive recovery (PR) in three tasks varying in specificity to the judo and in measurement of work performed: four upper-body Wingate tests (WT); special judo fitness test (SJFT); another match. For this purpose, three studies were conducted. Sixteen highly trained judo athletes took part in study 1, 9 in study 2, and 12 in study 3. During AR judokas ran (15 min) at the velocity corresponding to 70% of 4 mmol l(-1) blood lactate intensity (approximately 50% VO(2) peak), while during PR they stayed seated at the competition area. The results indicated that the minimal recovery time reported in judo competitions (15 min) is long enough for sufficient recovery of WT performance and in a specific high-intensity test (SJFT). However, the odds ratio of winning a match increased ten times when a judoka performed AR and his opponent performed PR, but the cause of this phenomenon cannot be explained by changes in number of actions performed or by changes in match's time structure.

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This study aimed to describe and compare the ventilation behavior during an incremental test utilizing three mathematical models and to compare the feature of ventilation curve fitted by the best mathematical model between aerobically trained (TR) and untrained (UT) men. Thirty five subjects underwent a treadmill test with 1 km·h(-1) increases every minute until exhaustion. Ventilation averages of 20 seconds were plotted against time and fitted by: bi-segmental regression model (2SRM); three-segmental regression model (3SRM); and growth exponential model (GEM). Residual sum of squares (RSS) and mean square error (MSE) were calculated for each model. The correlations between peak VO2 (VO2PEAK), peak speed (SpeedPEAK), ventilatory threshold identified by the best model (VT2SRM) and the first derivative calculated for workloads below (moderate intensity) and above (heavy intensity) VT2SRM were calculated. The RSS and MSE for GEM were significantly higher (p < 0.01) than for 2SRM and 3SRM in pooled data and in UT, but no significant difference was observed among the mathematical models in TR. In the pooled data, the first derivative of moderate intensities showed significant negative correlations with VT2SRM (r = -0.58; p < 0.01) and SpeedPEAK (r = -0.46; p < 0.05) while the first derivative of heavy intensities showed significant negative correlation with VT2SRM (r = -0. 43; p < 0.05). In UT group the first derivative of moderate intensities showed significant negative correlations with VT2SRM (r = -0.65; p < 0.05) and SpeedPEAK (r = -0.61; p < 0.05), while the first derivative of heavy intensities showed significant negative correlation with VT2SRM (r= -0.73; p< 0.01), SpeedPEAK (r = -0.73; p < 0.01) and VO2PEAK (r = -0.61; p < 0.05) in TR group. The ventilation behavior during incremental treadmill test tends to show only one threshold. UT subjects showed a slower ventilation increase during moderate intensities while TR subjects showed a slower ventilation increase during heavy intensities. Key pointsThe increase of ventilation during incremental exercise tends to show only one metabolic transition point.The presence of a threshold process or a continuous process in ventilation during incremental exercise seems to be only a methodological matter.The ventilatory efficiency can be employed to distinguish trained than untrained subjects once this index is associated with aerobic parameters. When analyzed the whole curve, trained subjects show a better ventilatory efficiency at heavy intensities and untrained subjects show a better ventilatory efficiency at moderate intensities.