RESUMO
This study aimed to test the reproducibility of the 3-min all-out effort applied using shuttle running and compare its values to aerobic parameters. On the first day, 14 futsal players underwent an exhaustive test to determine the maximal incremental speed (MIS) and anaerobic threshold (AnT). On the second day, the participants performed the 3-min all-out effort (n=14), which was repeated after 48 h (third day) to test its reproducibility (n=11). Peak oxygen consumption (VÌ O2PEAK) and peak blood lactate concentrations ([La-]) were determined from 3-min all-out efforts performed through a 20-m shuttle run on the official court. The distance covered, mean speed, and critical speed (CS) during the 3-min all-out presented direct relationships with aerobic parameters determined through the incremental test (r>0.62). The distance covered above CS (D') presented a direct relationship with peak lactate concentrations induced by a 3-min all-out effort (r=0.81). Despite the acceptable levels of reproducibility observed for most of the 3-min all-out variables, the minimal detectable change for D' was high (72%). Our results demonstrated the potential use of mean speed to evaluate aerobic fitness. However, the applicability of the 3-min all-out shuttle run test to monitor training adaptations should be avoided, at least in nonexperienced athletes.
Assuntos
Corrida , Esportes de Equipe , Humanos , Teste de Esforço , Reprodutibilidade dos Testes , Anaerobiose , Limiar Anaeróbio , Ácido Láctico , Consumo de OxigênioRESUMO
The primary aim of this study was to compare the measured oxygen consumption (Measured-VO2) in a simulated futsal game (S-Game) with the estimated oxygen consumption (Estimated-VO2) through a regression equation between heart rate (HR) and oxygen consumption (VO2) (HR-VO2) in treadmill running, and a secondary aim was to calculate the total energy expenditure (EE) in S-Game. Ten professional players (22.20 ± 3.22 years) were evaluated. HR-VO2 was determined individually in the continuous test on the treadmill (ContTest). The Measured-VO2 in S-Game was compared with the Estimated-VO2 in the ContTest. Alactic and lactic pathways were estimated by VO2. The Estimated-VO2 presented no statistically significant difference with the Measured-VO2, using the paired t-test (p = 0.38). However, the correlation between Estimated- and Measured-VO2 was very weak (r = -0.05), and it presented poor agreement (concordance correlation coefficient = -0.04). In addition, a Bland-Altman plot presented bias of -2.8 ml/kg/min and individual difference as large as 19 ml/kg/min. The HR-VO2 determined by the ContTest was not a good individual predictor of VO2. The high intensity and intermittent nature of the futsal game possibly caused dissociation in the HR-VO2 relationship. ContTest is not recommended for estimating VO2 and calculating individual EE in the futsal game. This is recommended only for the group mean. The total EE in S-Game was 13.10 ± 1.25 kcal.min-1 (10.81 ± 1.57 metabolic equivalents). The contributions from the metabolic pathways were as follows: aerobic (93%), alactic (5%), and lactic (2%).
RESUMO
Physiological responses in futsal have not been studied together with temporal information about the players' stay on the court. The aim of this study was to compare heart rate (HR) and blood lactate concentration ([La-]) responses between 1-H and 2-H considering the time of permanency of the players on the court at each substitution in a futsal match. HR was recorded during entire match and [La-] was analyzed after each substitution of seven players. %HRmean (89.61 ± 2.31 vs. 88.03 ± 4.98 %HRmax) and [La-] mean (8.46 ± 3.01 vs. 8.17 ± 2.91 mmol·L-1) did not differ between 1-H and 2-H (ES, trivial-small). Time in intensity zones of 50-100 %HRmax differed only in 60-70 %HRmax (ES, moderate). HR coefficient of variation throughout the match was low (7%) and among the four outfield players on the court (quartets, 5%). Substitutions (2 player's participation in each half), time of permanence on the court (7.15 ± 2.39 vs. 9.49 ± 3.80 min), ratio between time in- and out-ratio on the court (In:Outcourt = 1:1.30 ± 1:0.48 vs. 1:1.05 ± 1:0.55 min) also were similar between 1-H and 2-H (ES, moderate and small, respectively). Balancing the number of substitutions, and the In:Outcourt ratio of players in both halves of the match, playing lower time at 1-H, ~8 min for each participation in the match, made it possible to maintain intensity of the match in 2-H similar to the 1H. These results are a good guidance to coaches and for application in future studies.
RESUMO
The aim of the study was to investigate the effects of acute supplementation of sodium bicarbonate (NaHCO3) on maximal accumulated oxygen deficit (MAOD) determined by a single supramaximal effort (MAODALT) in running and the correlation with 200- and 400-m running performances. Fifteen healthy men (age, 23 ± 4 years; maximal oxygen uptake, 50.6 ± 6.1 mL·kg(-1)·min(-1)) underwent a maximal incremental exercise test and 2 supramaximal efforts at 110% of the intensity associated with maximal oxygen uptake, which was carried out after ingesting either 0.3 g·kg(-1) body weight NaHCO3 or a placebo (dextrose) and completing 200- and 400-m performance tests. The study design was double-blind, crossover, and placebo-controlled. Significant differences were found between the NaHCO3 and placebo conditions for MAODALT (p = 0.01) and the qualitative inference for substantial changes showed a very likely positive effect (98%). The lactic anaerobic contribution in the NaHCO3 ingestion condition was significantly higher (p < 0.01) and showed a very likely positive effect (99% chance), similar to that verified for peak blood lactate concentration (p < 0.01). No difference was found for time until exhaustion (p = 0.19) or alactic anaerobic contribution (p = 0.81). No significant correlations were observed between MAODALT and 200- and 400-m running performance tests. Therefore, we can conclude that both MAODALT and the anaerobic lactic metabolism are modified after acute NaHCO3 ingestion, but it is not correlated with running performance.