Máxima fase estável de lactato sanguíneo e potência crítica em ciclistas bem treinados

Abstract

RESUMoO principal objetivo deste estudo foi comparar a intensidade correspondente à máxima fase estável de lactato (MLSS) e a potência crítica (PC) durante o ciclismo em indivíduos bem treinados. Seis ciclistas do sexo masculino (25,5 ± 4,4 anos, 68,8 ± 3,0kg, 173,0 ± 4,0cm) realizaram em diferentes dias os seguintes testes: exercício incremental até a exaustão para a determinação do pico de consumo de oxigênio (VO 2 pico) e sua respectiva intensidade (IVO 2 pico); cinco a sete testes de carga constante para a determinação da MLSS e da PC; e um exercício até a exaustão na PC. A MLSS foi considerada com a maior intensidade de exercício onde a concentração de lactato não aumentou mais do que 1mM entre o 10 o e o 30 o min de exercício. Os valores individuais de potência (95, 100 e 110% IVO 2 pico) e seu respectivo tempo máximo de exercício (Tlim) foram ajustados a partir do modelo hiperbólico de dois parâmetros para a determinação da PC. Embora altamente correlacionadas (r = 0,99; p = 0,0001), a PC (313,5 ± 32,3W) foi significantemente maior do que a MLLS (287,0 ± 37,8W) (p = 0,0002). A diferença percentual da PC em relação à MLSS foi de 9,5 ± 3,1%. No exercício realizado na PC, embora tenha existido componente lento do VO 2 (CL = 400,8 ± 267,0 ml.min -1 ), o VO 2 pico não foi alcançado (91,1 ± 3,3 %). Com base nesses resultados pode-se concluir que a PC e a MLSS identificam diferentes intensidades de exercício, mesmo em atletas com elevada aptidão aeróbia. Entretanto, o percentual da diferença entre a MLLS e PC (9%) indica que relação entre esses dois índices pode depender da aptidão aeróbia. Durante o exercício realizado até a exaustão na PC, o CL que é desenvolvido não permite que o VO 2 pico seja alcançado.Palavras-chave: ciclismo, consumo de oxigênio, exercício aeróbio. aBStRaCtThe main objective of this study was to compare the intensity corresponding to the maximal lactate steady state (MLSS) and critical power (CP) in well-trained cyclists. Six male cyclists (25.5 ± 4.4 years, 68.8 ± 3.0 kg, 173.0 ± 4.0 cm) performed in different days the following tests: incremental exercise test until exhaustion to determine peak oxygen uptake (VO 2 peak) and its respective intensity (IVO 2 peak); five to seven constant workload tests to determine MLSS and CP and; one exhaustion test at CP. MLSS was defined as the highest workload at which blood lactate concentration did not increase by more than 1 mM between minutes 10 and 30 of the constant workload. Individual values for power-Tlim from the constant workload tests (95, 100 and 110% IVO 2 peak) were fit to the hyperbolic model of two-parameter to determine CP. Although highly correlated (r = 0.99; p = 0.0001), CP (313.5 + 32.3 W) was statistically higher than MLSS (287.0 + 37.8 W) (p = 0.0002). The percentual difference between CP and MLSS was 9.5 + 3.1 %. During exercise performed at CP, although a slow component of VO 2 has developed (SC = 400.8 + 267.0 ml.min -1 ), the VO 2 peak was not attained (91.1 + 3.3 %). Based on these results, it can be concluded that CP and...

Máximo estado estável de lactato estimado por diferentes métodos de determinação

“…AT1 was not significantly different from MLSS and there was a moderately significant correlation between the variables (r = 0.68). This result is in agreement with previous studies carried out with endurance runners 5,12 , cyclists 4,[13][14][15][16] , team sports 18 , physically active individuals 19 and untrained individuals 4 . Jones and Doust 12 showed that endurance runners' AT1 and MLSS were significantly similar and highly correlated (r = 0.93).…”

“…Studies with exercises on stationary bicycles for both trained cyclists and untrained individuals showed that the intensity that corresponded to the AT and the fixed [La] of 3.5 mmol.L -1 was not different from the MLSS 4,[13][14][15] . Though the AT for the fixed [La] was similar to MLSS, other studies with running 5,12,18,19 and cycling 4,[13][14][15][16] , and others with different exercise modalities, have shown a difference between the two variables 11,17,19 . The main criticism in relation to the use of this method is that it does not evaluate the individual kinetics of the lactate curve during an incremental test.…”

“…Several studies have tested the validity of methods for MLSS determination in endurance runners 5,9,11,12 , cyclists 11,[13][14][15][16] , rowers 17 , team sports 9,18 , physically active individuals [19][20][21][22] and untrained individuals 4 . In the specific case of runners, studies have yet to directly investigate the relationship between MLSS and anaerobic threshold (AT) determined by the methods proposed by Berg et al 7 , Cheng et al 8 and Baldari and Guidetti 10 .…”

Agreement Between Maximal Lactate Steady State and Critical Power in Different Sports: A Systematic Review and Bayesian’s Meta-Regression

“…From the 36 studies, 31 were peer reviewed (26,28,34,37–39,47,48,61,70,71,78,83,85,86,90,91,98,102–104,107,109,110,112,117,119,120,123–125) and 5 were “gray literature” including 1 conference abstract (45) and 4 thesis or dissertations or monographs (15,32,64,121). Studies' main characteristics regarding MLSS and CP testing protocols and the observed study-level effect sizes (trueμ^CP−MLSS and trueσ^CP−MLSS) are shown in Table 2.…”

Componente lento da cinética do VO2: determinantes fisiológicos e implicações para o desempenho em exercícios aeróbios

“…Isso porque reserva o recurso do modelo matemático ao tratamento da resposta principal da cinética do VO 2 , destacando-a da reposta subsequente. Assim, possibilita a detecção do início e amplitude do CL pela observação pontual do eixo do tempo e comparação do volume de O 2 ao final do exercício 5,34,35 . Quadro 1.…”