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1.
J Strength Cond Res ; 38(6): e320-e339, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38781475

RESUMO

ABSTRACT: Borszcz, FK, de Aguiar, RA, Costa, VP, Denadai, BS, and de Lucas, RD. Agreement between maximal lactate steady state and critical power in different sports: A systematic review and Bayesian's meta-regression. J Strength Cond Res 38(6): e320-e339, 2024-This study aimed to systematically review the literature and perform a meta-regression to determine the level of agreement between maximal lactate steady state (MLSS) and critical power (CP). Considered eligible to include were peer-reviewed and "gray literature" studies in English, Spanish, and Portuguese languages in cyclical exercises. The last search was made on March 24, 2022, on PubMed, ScienceDirect, SciELO, and Google Scholar. The study's quality was evaluated using 4 criteria adapted from the COSMIN tool. The level of agreement was examined by 2 separate meta-regressions modeled under Bayesian's methods, the first for the mean differences and the second for the SD of differences. The searches yielded 455 studies, of which 36 studies were included. Quality scale revealed detailed methods and small samples used and that some studies lacked inclusion/exclusion criteria reporting. For MLSS and CP comparison, likely (i.e., coefficients with high probabilities) covariates that change the mean difference were the MLSS time frame and delta criteria of blood lactate concentration, MLSS number and duration of pauses, CP longest predictive trial duration, CP type of predictive trials, CP model fitting parameters, and exercise modality. Covariates for SD of the differences were the subject's maximal oxygen uptake, CP's longest predictive trial duration, and exercise modality. Traditional MLSS protocol and CP from 2- to 15-minute trials do not reflect equivalent exercise intensity levels; the proximity between MLSS and CP measures can differ depending on test design, and both MLSS and CP have inherent limitations. Therefore, comparisons between them should always consider these aspects.


Assuntos
Teorema de Bayes , Ácido Láctico , Humanos , Ácido Láctico/sangue , Desempenho Atlético/fisiologia , Esportes/fisiologia , Força Muscular/fisiologia
2.
Int J Sports Med ; 42(2): 153-160, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32842155

RESUMO

The objective of the present study was to determine the validity of Carminatti's shuttle run incremental test-T-Car derived parameters in estimating the maximal lactate steady state determined in shuttle run format. Eighteen soccer players performed a T-Car test, and several trials to determine the maximal lactate steady state. From T-Car were derived the heart rate deflection point, peak speed, maximal heart rate and parameters resulting from percentage of peak measures. The validity was accessed by Bland-Altman plots, linear regressions, and two one-sided tests of equivalence analysis. The results showed the speed at 80.4% of T-Car peak speed, the heart rate deflection point and the 91.4% of maximal heart rate were equivalent to maximal lactate steady state (Mean difference; ±90% compatibility interval; -0.8; ±1.5%, -0.4; ±1.1%, and 0.0; ±2.7%, respectively). Additionally, peak speed during the T-Car test was a stronger predictor of maximal lactate steady state (MLSS [km/h]=2.57+0.65 × sPeak; r=0.82 [90% CI; 0.62-0.92], standard error of the estimate=3.6%; 90% CI ×/÷1.4). Therefore, soccer players can use the T-Car derived parameters as a noninvasive and practical alternative to estimate the specific maximal lactate steady state for soccer.


Assuntos
Teste de Esforço/normas , Frequência Cardíaca/fisiologia , Ácido Láctico/sangue , Aptidão Física/fisiologia , Corrida/fisiologia , Futebol/fisiologia , Adolescente , Adulto , Estudos Transversais , Humanos , Masculino , Adulto Jovem
3.
Int J Sports Med ; 41(3): 175-181, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31952081

RESUMO

Functional threshold power (FTP) is defined as the highest power that a cyclist can maintain in a quasi-steady state without fatigue for approximately 1 hour. To improve practicality, a 20-minute time-trial test was proposed, where FTP is represented by 95% of the mean power produced. It is preceded by a specific 45-min warm-up, with periods of low intensity, fast accelerations, and a 5-min time-trial. Thus, the aim of this study was to determine the reliability of this protocol, including the reliability of the warm-up, pacing strategy, and FTP determination. For this purpose, 25 trained cyclists performed a familiarization and two other tests separated by seven days. The coefficient of variation (CV [%]), intraclass correlation coefficient (ICC), and change in the mean between test and retest were calculated. The results show that the 20-min time-trial was reliable (CV=2.9%, ICC=0.97), despite a less reliable warm-up (CV=5.5%, ICC=0.84). The changes in the mean between the test and retest were trivial to small for all measurements, and the pacing strategy was consistent across all trials. These results suggest that FTP determination with a 20-min protocol was reliable in trained cyclists.


Assuntos
Limiar Anaeróbio/fisiologia , Ciclismo/fisiologia , Comportamento Competitivo/fisiologia , Teste de Esforço/métodos , Adulto , Humanos , Masculino , Consumo de Oxigênio , Reprodutibilidade dos Testes , Exercício de Aquecimento/fisiologia
4.
J Strength Cond Res ; 34(1): 270-280, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31877120

RESUMO

Silva, FCd, Iop, RdR, Andrade, A, Costa, VP, Gutierres Filho, PJB, and Silva, Rd. Effects of physical exercise on the expression of microRNAs: A systematic review 34(1): 270-280, 2020-Studies have detected changes in the expression of miRNAs after physical exercise, which brings new insight into the molecular control of adaptation to exercise. Therefore, the objective of the current systematic review of experimental and quasiexperimental studies published in the past 10 years was to assess evidence related to acute effects, chronic effects, and both acute and chronic effects of physical exercise on miRNA expression in humans, as well as its functions, evaluated in serum, plasma, whole blood, saliva, or muscle biopsy. For this purpose, the following electronic databases were selected: MEDLINE by Pubmed, SCOPUS, Web of Science, and also a manual search in references of the selected articles to April 2017. Experimental and quasiexperimental studies were included. Results indicate that, of the 345 studies retrieved, 40 studies met the inclusion criteria and two articles were included as a result of the manual search. The 42 studies were analyzed, and it can be observed acute and chronic effects of physical exercises (aerobic and resistance) on the expression of several miRNAs in healthy subjects, athletes, young, elderly and in patients with congestive heart failure, chronic kidney disease, diabetes mellitus type 2 associated with morbid obesity, prediabetic, and patients with intermittent claudication. It is safe to assume that miRNA changes, both in muscle tissues and bodily fluids, are presumably associated with the benefits induced by acute and chronic physical exercise. Thus, a better understanding of changes in miRNAs as a response to physical exercise might contribute to the development of miRNAs as therapeutic targets for the improvement of exercise capacity in individuals with any given disease. However, additional studies are necessary to draw accurate conclusions.


Assuntos
Exercício Físico/fisiologia , MicroRNAs/sangue , Músculo Esquelético/metabolismo , Saliva/metabolismo , Idoso , Humanos , Masculino , MicroRNAs/metabolismo
6.
Int J Sports Med ; 39(10): 737-742, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29801189

RESUMO

Functional threshold power is defined as the highest power output a cyclist can maintain in a quasi-steady state for approximately 60 min (FTP60). In order to improve practicality for regular evaluations, FTP60 could theoretically be determined as 95% of the mean power output in a 20-min time trial (FTP20). This study tested this assumption and the validity of FTP20 and FTP60 against the individual anaerobic threshold (IAT). Twenty-three trained male cyclists performed an incremental test to exhaustion, 20- and 60-min time trials, and a time to exhaustion at FTP20. Power output, heart rate and oxygen uptake representing FTP20, FTP60 and IAT were not different (p>0.05), and large to very large correlations were found (r=0.61 to 0.88). Bland-Altman plots between FTP20, FTP60 and IAT showed small bias (-1 to -5 W), but large limits of agreement ([-40 to 32 W] to [-62 to 60 W]). Time to exhaustion at FTP20 was 50.9±15.7 min. In conclusion, FTP20 and FTP60 should not be used interchangeably on an individual basis and their validity against IAT should be interpreted with caution.


Assuntos
Limiar Anaeróbio/fisiologia , Ciclismo/fisiologia , Teste de Esforço/métodos , Resistência Física/fisiologia , Adulto , Frequência Cardíaca , Humanos , Ácido Láctico/sangue , Masculino , Consumo de Oxigênio , Percepção/fisiologia , Esforço Físico , Reprodutibilidade dos Testes , Fatores de Tempo
7.
J Sports Sci ; 36(5): 485-491, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28423987

RESUMO

Reproducibility of frequency content from surface electromyography (sEMG) signals has not been assessed and it is unknown if incremental load testing design could affect sEMG in cycling. The goals of this study were to assess the reproducibility of measures from sEMG frequency content between sessions and to compare these frequency components between a ramp and a step incremental cycling test. Eighteen cyclists performed four incremental load cycling tests to exhaustion. Two tests were performed using a step increment (load started at 100 W for 3 min followed by increments of 30 W every 3 min) and two were performed using a ramp increment (load started at 100 W for 1 min followed by increments of 30 W·min-1). sEMG was monitored bilaterally for the rectus femoris and vastus lateralis throughout the tests and converted into overall activation (whole signal bandwidth), high- and low-frequency contents. The reproducibility of the frequency content ranged from none to strong (ICC = 0.07-0.90). Vastus lateralis activation was larger at the step compared to the ramp test (P < 0.01), without differences for rectus femoris (P = 0.22-0.91) and for the high-frequency (P = 0.28-0.95) and low-frequency contents (P = 0.13-0.94). sEMG from vastus lateralis and rectus femoris presented none to strong reproducibility. Vastus lateralis is more activated in step test design.


Assuntos
Ciclismo/fisiologia , Eletromiografia , Perna (Membro)/fisiologia , Músculo Esquelético/fisiologia , Adulto , Teste de Esforço/métodos , Humanos , Masculino , Fadiga Muscular/fisiologia , Músculo Quadríceps/fisiologia , Reprodutibilidade dos Testes , Adulto Jovem
8.
Appl Physiol Nutr Metab ; 42(4): 391-398, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28177733

RESUMO

The aim of this study was to determine the effects of block training (BL) on pacing during a 20-km hilly cycling time trial (TT) in trained cyclists. Twenty male cyclists were separated into 2 groups: control and BL. The training of each cyclist was monitored during a period of 3 weeks. In the first week cyclists performed an overload period of 7 consecutive days of high-intensity interval training followed by 2 weeks of normal training. Cyclists performed 1 TT before intervention and 2 TT after 7 and 14 days at the end of training. Each training session consisted of 10 sets of 3 repeated maximal-effort sprints (15, 30, and 45 s) with an effort/recovery duration ratio of 1:5. The main finding of this study was that the power output displayed a significantly higher start from the start until the halfway point of the TT (p < 0.05). Additionally, power output was characterized by a significant higher end spurt in the final 2 km in the BL after 2 weeks at the end of training (p < 0.05). In addition, after 2 weeks at the end of the overload period the distribution of cadence was significantly lower throughout the TT (p < 0.01). Therefore, a short period of consecutive days of intense training enhances cycling performance and changes the power output in the beginning and final part of the TT in trained cyclists.


Assuntos
Atletas , Desempenho Atlético , Tolerância ao Exercício , Treinamento Intervalado de Alta Intensidade , Descanso , Adulto , Altitude , Ciclismo , Teste de Esforço , Fadiga/sangue , Fadiga/etiologia , Fadiga/prevenção & controle , Frequência Cardíaca , Treinamento Intervalado de Alta Intensidade/efeitos adversos , Humanos , Ácido Láctico/sangue , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio , Fatores de Tempo
9.
Eur J Sport Sci ; 15(4): 265-70, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25135192

RESUMO

The aim of this study was to determine the relative and absolute reliability of second lactate turnpoint using fixed and individual blood lactate method in competitive cyclists. Twenty-eight male, well-trained cyclists (30.2 ± 10.1 years, 72.0 ± 7.4 kg, 177.3 ± 4.7 cm) were recruited to participate in this study. Cyclists completed two incremental cycling tests to exhaustion over a period of 7 days to determine their peak power output, maximal oxygen uptake, maximal heart rate, maximal blood lactate concentration and two lactate turnpoint criteria. The fixed blood concentration criterion (3.5 mM) and an individual criterion were assessed by a lactate-power curve, considering power output, heart rate and oxygen uptake. The main finding of this study was that both lactate turnpoint criteria showed identical low within-subject variation for power output (2.8% coefficient of variation). High values for test-retest correlations ranging from r = 0.70 to r = 0.94 were found for all variables in both threshold criteria. In conclusion, the individual and fixed method to determine the second lactate turnpoint showed similar high absolute and relative reliability in competitive cyclists.


Assuntos
Ciclismo/fisiologia , Ácido Láctico/sangue , Adulto , Teste de Esforço , Frequência Cardíaca , Humanos , Masculino , Consumo de Oxigênio , Reprodutibilidade dos Testes , Adulto Jovem
10.
Rev. bras. cineantropom. desempenho hum ; 16(4): 466-474, Jul-Aug/2014. tab
Artigo em Português | LILACS | ID: lil-715680

RESUMO

Os objetivos deste estudo foram: determinar e comparar índices fisiológicos obtidos em teste de laboratório e pista (teste de pista da Universidade de Montreal - UMTT) em corredores de endurance; analisar a capacidade de predição do VO2max, vVO2max e LAn determinados no laboratório e no UMTT para a performance nas distâncias de 1.500 m, 5.000 m e 10.000 m; analisar os efeitos da distância da prova na relação entre os índices fisiológicos VO2max, vVO2max e LAn com a performance. Participaram deste estudo, 10 corredores moderadamente treinados que realizaram os seguintes testes: provas simuladas nas distâncias de 10.000 m, 5.000 m e 1.500 m; dois testes incrementais máximos (laboratório e pista) para determinar os índices VO2max, vVO2max e LAn. Não houve diferenças significativas entre o VO2max, vVO2max e LAn determinados em ambos os protocolos. De acordo com a análise de regressão múltipla, referente ao teste de laboratório, a vVO2max foi a única variável selecionada para explicar a performance nas provas de 1.500 e 5.000 m (62 e 35%, respectivamente). Do mesmo modo, dentre as variáveis determinadas no UMTT, somente a vVO2max explicou a performance nestas distâncias (78 e 66%, respectivamente). Por outro lado, o LAn determinado no laboratório e no UMTT explicou 38 e 52% da performance nos 10.000 m, respectivamente. Pode-se concluir que a predição da performance aeróbia de corredores de endurance moderadamente treinados, a partir do VO2max, vVO2max e LAn, determinados em laboratório e no UMTT, é dependente da distância da prova analisada.


The objectives of this study were: 1) determine and compare physiological indexes from laboratory and track tests (Université de Montréal Track Test - UMTT) in endurance runners; 2) analyze the predictive capacity of VO2max, vVO2max and AT with the running performance at 1,500 m, 5,000 m and 10,000 m time trials; 3) analyze the effects of running distance on the relationship between the physiological indexes with aerobic performance. The study included 10 moderately trained endurance runners who performed the following series of tests on different days: 10,000 m, 5,000 m, and 1,500 m time trials on a 400 m track; two maximal incremental tests (laboratory and track) to determine the VO2max, vVO2max, and AT. There were no significant differences between VO2max, vVO2max and AT determined in both protocols. The multiple regression analysis revealed that vVO2max was the only index from laboratory associated with running performance at 1,500 and 5,000 m (62 and 35%, respectively). In addition, vVO2max from UMTT explained the running performance for the same previous distance (78 and 66%, respectively). On the other hand, the AT determined in both incremental tests explained 38 and 52% of performance at 10,000 m time trial, respectively. Thus, the prediction of endurance performance of long distance runners using VO2max, vVO2max and AT determined in the laboratory and UMTT tests depends on the running distance.

11.
Rev. bras. cineantropom. desempenho hum ; 14(3): 264-275, 2012. ilus, tab
Artigo em Português | LILACS | ID: lil-624471

RESUMO

O objetivo deste estudo foi determinar e comparar o limiar anaeróbio (LAn) obtido por quatro diferentes métodos com o máximo estado estável de lactato (MLSS) em corredores de endurance. Nove corredores moderadamente treinados realizaram, em diferentes dias, os seguintes testes: um teste incremental máximo para determinação do consumo máximo de oxigênio (VO2max), velocidade correspondente ao VO2max (vVO2max) e resposta do lactato sanguíneo e; dois a cinco testes de intensidade constante, com 30 min de duração, para determinação do MLSS. A partir do teste incremental, foram utilizados quatro métodos de determinação do LAn: LAn1 - velocidade correspondente a [La] fixa de 3,5 mmol.L-1; LAn2 - velocidade referente a [La] do menor equivalente [La]-velocidade somado com 1,5 mmol.L-1; LAn3 - velocidade correspondente ao Dmax; LAn4 - velocidade anterior ao segundo incremento consecutivo de [La] maior que 0,5 mmol.L-1. Não existiram diferenças significativas entre o MLSS e o LAn determinado pelos quatro métodos estudados. Entretanto, a análise de Bland-Altman expressou a extensão da discordância entre as variáveis quando os sujeitos foram analisados individualmente. Houve correlações significativas entre MLSS e LAn1 (r = 0,68; p = 0,04) e entre MLSS e o LAn2 (r = 0,79; p = 0,01). Assim, apesar de não haver diferença significativa entre os métodos de determinação do LAn com o MLSS, deve-se ter cautela para utilizá-los de forma intercambiável.


The aim of this study was to compare anaerobic threshold (AT) as determined by four different methods with maximal lactate steady state (MLSS) in endurance runners. Nine moderately trained runners performed the following tests on different days: a maximal incremental exercise test to determine maximal oxygen uptake (VO2max), velocity at VO2max (vVO2max), and blood lactate response; and two to five 30-min constant load tests to determine MLSS. Based on the incremental test, four methods of AT determination were used: AT1 - velocity at 3.5 mmol.L-1 blood lactate; AT2 - velocity corresponding to the minimum lactate-velocity equivalentplus 1.5 mmol.L-1; AT3 - velocity at Dmax; and AT4 - velocity before the second consecutive blood lactate increase greater than 0.5 mmol.L-1. There were no significant differences between MLSS and AT as determined by four different methods. However, the Bland-Altman analysis showed the extent of disagreement between variables when the subjects were analyzed individually. MLSS was significantly correlated with AT1 (r=0.68; p=0.04) and AT2 (r=0.79; p=0.01). Thus, although no significant differences were found between AT methods and MLSS, one should be cautious about using these methods interchangeably.

12.
Rev. bras. educ. fís. esp ; 24(3): 379-387, jul.-set. 2010. graf, tab
Artigo em Português | LILACS | ID: lil-604576

RESUMO

O objetivo deste estudo foi verificar a resposta de frequência cardíaca (FC) durante as competições de "Cross-country" Olímpico (XCO). Quatorze "mountain bikers" foram separados em dois grupos: elite (n = 6; 26,5 ± 3,6 anos; 69,1 ± 2,1 kg; 174,0 ± 1,2 cm; 5,9 ± 0,9 por cento G; 9,0 ± 1,3 anos de treinamento) e amadores (n = 8; 25,6 ± 7,7 anos; 67,7 ± 7,0 kg; 175,5 ± 5,5 cm; 5,8 ± 2,1 por cento G; 8,3 ± 5,7 anos de treinamento). Os participantes foram submetidos a um teste progressivo para a identificação dos limiares metabólicos e seus respectivos valores de frequência cardíaca (FC) em cada zona de intensidade de esforço. Após intervalo mínimo de quatro dias os atletas da categoria elite foram avaliados através de monitores de FC durante a etapa brasileira da Copa do Mundo de XCO. Após 15 dias, todos os atletas foram avaliados no Campeonato Brasileiro de XCO. Os resultados indicaram que em ambas as competições, a média percentual da FC foi correspondente a 91-92 por cento da FCmáx. Nas competições, os atletas permaneceram durante diferentes tempos percentuais nas zonas de intensidade de esforço sendo 10,0-14,8 por cento no domínio leve; 23,1-30,1 por cento moderado e 55,1-66,9 por cento intenso. Assim, este estudo apresenta que as competições de XCO são realizadas em alta intensidade, principalmente após a largada.


The aim of this study was to verify and describe the intensity profile of cross-country mountain-biking races using heart rate (HR) recorded during races. Fourteen mountain bikers participated in two groups: elite (n = 6; 26.5 ± 3.6 years old; 69.1 ± 2.1 kg; 174.0 ± 1.2 cm; 5.9 ± 0.9 percent BF; 9.0 ± 1.3 years of training) and amateurs (n = 8; 25.6 ± 7.7 years; 67.7 ± 7.0 kg; 175.5 ± 5.5 cm; 5.8 ± 2.1 percent BF; 8.3 ± 5.7 years of training). Each cyclist was submitted to an incremental exercise test to determine the metabolic thresholds and the HR values at each threshold. After four days, only the athletes of elite category were tested during Brazilian round of XCO World Cup. Two weeks later both groups were evaluated in XCO Brazilian National Championship. The results showed that HR averaged 91-92 percent of HRmax. The exercise intensity zones showed different percentage of time spent during the races (10.0-14.8 percent easy; 23.1-30.1 percent moderate; 55.1-66.9 percent hard). This study shows that cross-country events are conducted at very high intensity, especially at the start of the race.


Assuntos
Humanos , Adulto , Ciclismo , Esforço Físico/fisiologia , Frequência Cardíaca
13.
Rev. bras. med. esporte ; 13(5): 317-320, set.-out. 2007. graf, tab
Artigo em Português | LILACS | ID: lil-483321

RESUMO

A prática regular de exercícios físicos tem sido considerada um dos mecanismos que auxiliam a melhoria de padrões da saúde e de qualidade de vida. Em conseqüência do crescimento da procura por academias de ginástica, as atividades físicas no meio líquido, com destaque para a bicicleta aquática, têm aumentado nos últimos anos. No entanto, há ainda carência de métodos para a avaliação e prescrição do treinamento aeróbio neste tipo de equipamento. O objetivo deste estudo foi propor uma adaptação do teste de Conconi et al. (1982) para bicicleta aquática. Foram testados 27 participantes (24 ± 6 anos, 171 ± 8cm, 66 ± 12kg) 15 do sexo masculino e 12 do feminino. Os participantes foram submetidos a um teste progressivo, realizado em bicicleta aquática, com carga inicial de 50RPM e incremento de 3RPM a cada minuto, até a exaustão. A FC foi registrada durante todo o teste. Para análise dos dados, foi utilizada estatística descritiva e o teste "t" de Student (P < 0,05) para comparação entre os sexos. O ponto de deflexão da FC (PDFC) foi identificado em 85 por cento dos sujeitos. Não houve diferença significativa na FCmáx (181 ± 12 e 181 ± 10BPM), PDFC (162 ± 10 e 172 ± 9BPM) e no por centoPDFCrpm (91 ± 4 e 90 ± 3 por centoRPMmáx) entre os sexos masculino e feminino respectivamente. Por outro lado, RPMmáx (81 ± 6 e 72 ± 5RPM), por centoPDFC (90 ± 5 e 93 ± 3 por centoFCmáx) e PDFCrpm (74 ± 6 e 66 ± 4RPM) foram significativamente diferentes. Assim, conclui-se que o teste de Conconi pode ser realizado em bicicleta aquática.


Physical exercise has been considered one of the mechanisms that improve health and quality of life. As a consequence of the enhanced demand for fitness centers, physical activities in liquid environment, especially aquatic cycling, have increased in the last years. However, methods of assessment and prescription of aerobic training in these equipments are still scarce. The objective of this study was to propose an adapted test of Conconi et al (1982) to aquatic bicycle. 27 participants (24 ± 6 years, 171 ± 8 cm, 66 ± 12 kg), 15 male and 12 female, were assessed. The participants have been submitted to a graded test in aquatic bicycle, with initial load of 50 RPM and increments of 3 RPM each minute, until exhaustion. HR was registered during the entire test. For data analysis, descriptive statistics were used as well as Student "t" test for comparison between genders. HRDP was identified in 85 percent of the subjects. There were not significant differences in HRmax (181 ± 12 and 181 ± 10 BPM), HRDP (162 ± 10 and 172 ± 9 BPM) and percentHRDPrpm (91 ± 4 and 90 ± 3 percent RPMmax) between males and females, respectively. On the other hand, RPMmax (81 ± 6 and 72 ± 5 RPM), percentHRDP (90 ± 5 and 93 ± 3 percentHRmax) and HRDPrpm (74 ± 6 and 66 ± 4 RPM) were significantly different. In conclusion, the adapted Conconi test can be performed in aquatic bicycle.

14.
Rev. bras. educ. fís. esp ; 21(3): 219-227, jul.-set. 2007. tab, graf
Artigo em Português | LILACS | ID: lil-514190

RESUMO

O objetivo deste estudo foi comparar os ajustes linear e sigmóide da freqüência cardíaca (FC) durante o exercícioincremental e analisar a validade destes modelos para identificar os limiares de transição metabólica em exercícioprogressivo, a partir de pontos de mudança no ajuste não-linear de Boltzmann. Dez “mountain bikers” de altorendimento (27,1 ± 7,4 anos; 67,0 ± 6,1 kg; 175,1 ± 4,1 cm; 6,1 ± 1,9 % de gordura) foram submetidos a testeprogressivo no ciclo-simulador, com carga inicial de 100 W e incremento de 30 W a cada 3 min até a exaustão. A FCfoi registrada batimento-a-batimento durante todo o teste. A curva da FC foi ajustada pela equação sigmóidede Boltzmann, com cálculo do Ponto de Inflexão da FC (PIFC = valor fixo V50 da equação) e Ponto de Deflexãoda FC (PDFC = método Dmáx). No final de cada estágio, foi determinada a concentração sanguínea de lactato([La]). O primeiro limiar de lactato (LL1) foi determinado através do cálculo do menor valor equivalente delactato/carga. Para o segundo limiar (LL2), foi acrescido 1,5 mmol.l-1 ao menor valor deste equivalente. Emtodos os atletas, o ajuste sigmóide da FC se apresentou mais adequado que o linear (p < 0,0001). O PIFC (161± 10 bpm) e PDFC (179 ± 5 bpm) foram identificados em oito e sete sujeitos, respectivamente. A FC e a cargado PIFC foram semelhantes às obtidas no LL2, enquanto que esses parâmetros foram menores no LL1 e maioresno PDFC. Assim, é possível especular que o PIFC está no mesmo domínio fisiológico do LL2. Entretanto, foramencontradas fracas associações entre os limiares de lactato com o PIFC e PDFC (-0,08 a 0,37).


The aim of this study was to compare the linear and sigmoid adjustments for the behavior of the heartrate (HR) during graded exercise test and to verify the validity of these models to identify metabolicthresholds from Boltzman's non-linear adjustment during incremental exercise. Ten high level mountainbikers (27.1 ± 7.4 years; 67.0 ± 6.1 kg; 175.1 ± 4.1 cm; 6.1 ± 1.9% estimated body fat) were submittedto graded exercise test in cycle-simulator, with initial load of 100 W and 30 W increments every 3 minuntil exhaustion. The HR behavior was fitted by Boltzman's sigmoid equation, and HR inflection point(HRIP = fixed value of V50 from equation) and HR deflection point (HRDP = Dmax method) were identified.Blood lactate samples were withdrawn at the end of each stage. The first lactate threshold (LT1) wasdetermined by the calculation of minimum value equivalent of lactate/work. To identify the secondlactate threshold (LT2), 1.5 mmol.l-1 was added to the LT1 value. In all athletes the sigmoid model wasmore appropriate than the linear one (p < 0.0001). The HRIP (161 ± 10 bpm) and HRDP (179 ± 5 bpm)were identified in 8 and 7 subjects, respectively. From the similarity of the results about the intensity inpower output and HR, it can be suppose that the HRIP is in the same physiological domain of the LT2,above to LT1 and lower to HRDP. However, were found poor association between lactate thresholds,HRIP and HRDP (-0.08 to 0.37).


Assuntos
Humanos , Masculino , Adulto , Ácido Láctico/metabolismo , Frequência Cardíaca/fisiologia
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