RESUMEN
The aim of this study was to determine the anaerobic threshold (AT) in a population of healthy and post-myocardial infarction men by applying Hinkley's mathematical method and comparing its performance to the ventilatory visual method. This mathematical model, in lieu of observer-dependent visual determination, can produce more reliable results due to the uniformity of the procedure. 17 middle-aged men (55±3 years) were studied in 2 groups: 9 healthy men (54±2 years); and 8 men with previous myocardial infarction (57±3 years). All subjects underwent an incremental ramp exercise test until physical exhaustion. Breath-by-breath ventilatory variables, heart rate (HR), and vastus lateralis surface electromyography (sEMG) signal were collected throughout the test. Carbon dioxide output (VËCO2), HR, and sEMG were studied, and the AT determination methods were compared using correlation coefficients and Bland-Altman plots. Parametric statistical tests were applied with significance level set at 5%. No significant differences were found in the HR, sEMG, and ventilatory variables at AT between the different methods, such as the intensity of effort relative to AT. Moreover, important concordance and significant correlations were observed between the methods. We concluded that the mathematical model was suitable for detecting the AT in both healthy and myocardial infarction subjects.
Asunto(s)
Umbral Anaerobio/fisiología , Modelos Estadísticos , Infarto del Miocardio/fisiopatología , Antropometría , Dióxido de Carbono/fisiología , Estudios Transversales , Electromiografía , Frecuencia Cardíaca , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Intercambio Gaseoso Pulmonar , Factores de RiesgoRESUMEN
Avaliar a frequencia cardiaca (FC) e sua variabilidade (VFC) em repouso e durante teste de exercicio fisico dinamico descontinuo tipo degrau (TEFDD-d) em homens saudaveis sedentarios (SS) e infartados ativos (IA); determinar e comparar o limiar de anaerobiose (LA) dos grupos estudados. Metodologia: forma estudados 10 SS (52,5 anos)e 6 IA (59,2 anos) em repouso nas posicoes supino e sentado e em TEFDD-d realizado em cicloergometro, iniciando na potencia com decrescimo de 5 W e acrescimo de 5 W. A Fc (bpm) e os intervalos R-R (iR-R) em ms foram captados batimento a batimento em repouso e em TEFDD-d. Foram calculados os indices RMSSD dos iR_r e a FC media das condicoes de repouso e do trecho estavel de cada nivel de potencia. O LA foi determinado aplicando o modelo semiparametrico aos dados de Fc. Os testes estatisticos utilizados forma Wilcoxon, Mann Whitney e Friedmann, nivel de significancia p < 0,05. Resultados: Em repouso os valores de RMSSD dos iR-R e da FC nao atingiram diferencas estatisticas significativas entre os grupos, ja os SS apresentaram diferencas significativas nos valores de Fc durante a mudanca postural. No nivel potencia do LA ambos os grupos nao apresentaram reducoes significativas da VFC em comparacao com 25 W. Conclusao: nossos resultados sugerem que a atividade fisica regular realizada pelos IA contribuiu para manter a capacidade aerobica como modulacao autonomica da FC similares a dos SS
Asunto(s)
Anaerobiosis , Enfermedad Coronaria , Ejercicio Físico , Frecuencia Cardíaca , Infarto del MiocardioRESUMEN
The objective of the present study was to characterize the heart rate (HR) patterns of healthy males using the autoregressive integrated moving average (ARIMA) model over a power range assumed to correspond to the anaerobic threshold (AT) during discontinuous dynamic exercise tests (DDET). Nine young (22.3 +/- 1.57 years) and 9 middle-aged (MA) volunteers (43.2 +/- 3.53 years) performed three DDET on a cycle ergometer. Protocol I: DDET in steps with progressive power increases of 10 W; protocol II: DDET using the same power values as protocol 1, but applied randomly; protocol III: continuous dynamic exercise protocol with ventilatory and metabolic measurements (10 W/min ramp power), for the measurement of ventilatory AT. HR was recorded and stored beat-to-beat during DDET, and analyzed using the ARIMA (protocols I and II). The DDET experiments showed that the median physical exercise workloads at which AT occurred were similar for protocols I and II, i.e., AT occurred between 75 W (116 bpm) and 85 W (116 bpm) for the young group and between 60 W (96 bpm) and 75 W (107 bpm) for group MA in protocols I and II, respectively; in two MA volunteers the ventilatory AT occurred at 90 W (108 bpm) and 95 W (111 bpm). This corresponded to the same power values of the positive trend in HR responses. The change in HR response using ARIMA models at submaximal dynamic exercise powers proved to be a promising approach for detecting AT in normal volunteers.
Asunto(s)
Umbral Anaerobio/fisiología , Presión Sanguínea/fisiología , Prueba de Esfuerzo/métodos , Frecuencia Cardíaca/fisiología , Adulto , Humanos , Masculino , Persona de Mediana EdadRESUMEN
The objective of the present study was to characterize the heart rate (HR) patterns of healthy males using the autoregressive integrated moving average (ARIMA) model over a power range assumed to correspond to the anaerobic threshold (AT) during discontinuous dynamic exercise tests (DDET). Nine young (22.3 ± 1.57 years) and 9 middle-aged (MA) volunteers (43.2 ± 3.53 years) performed three DDET on a cycle ergometer. Protocol I: DDET in steps with progressive power increases of 10 W; protocol II: DDET using the same power values as protocol 1, but applied randomly; protocol III: continuous dynamic exercise protocol with ventilatory and metabolic measurements (10 W/min ramp power), for the measurement of ventilatory AT. HR was recorded and stored beat-to-beat during DDET, and analyzed using the ARIMA (protocols I and II). The DDET experiments showed that the median physical exercise workloads at which AT occurred were similar for protocols I and II, i.e., AT occurred between 75 W (116 bpm) and 85 W (116 bpm) for the young group and between 60 W (96 bpm) and 75 W (107 bpm) for group MA in protocols I and II, respectively; in two MA volunteers the ventilatory AT occurred at 90 W (108 bpm) and 95 W (111 bpm). This corresponded to the same power values of the positive trend in HR responses. The change in HR response using ARIMA models at submaximal dynamic exercise powers proved to be a promising approach for detecting AT in normal volunteers.
Asunto(s)
Adulto , Persona de Mediana Edad , Humanos , Masculino , Umbral Anaerobio/fisiología , Presión Sanguínea/fisiología , Prueba de Esfuerzo/métodos , Frecuencia Cardíaca/fisiologíaRESUMEN
O objetivo deste estudo foi avaliar e comparar a variabilidade da frequencia cardiaca(VFC) em repouso supino e sentado de 10 homens de meia idade saudaveis (SA), 9 hipertensos (HA) e 9 com infarto do miocardio (IM), com idade media de 52, 62 e 56 anos, respectivamente. Os voluntarios SA nao praticavam atividade fisica frequentemente e os voluntarios HA e IM participavam de um programa de treinamento fisico aerobico (TFA) ha aproximadamente 3 anos. A frequencia cardiaca (FC) e os intervalos R-R(iR-R - ms) foram coletdos durante 900 s nas posicoes supina e sentada, e os voluntarios foram orientados a manter-se em repouso. Para a analise dos dados de dominio do tempo (DT), foi utilizado o indice RMSSD dos iR-R (ms). Para o dominio da frequencia (DF), foi aplicado um modelo auto-regressivo e obtidas as bandas de frequencia muito baixa (MBF), baixa (BF) e alta (AF), sendo os componentes BF e AF expressos em unidades normalizadas e na razao BF/AF. Foram utilizados os testes estatisticos nao-parametricos de Wilcoxon, de kruskall-Wallis e pos-hoc de Dunn. O nivel de significancia foi de a=5(por cento). Nao foram observadas diferencas estatisticamente significativas nos indices de VFC, avaliados no DT e no DF nas condicoes supino e sentado, nas comparacoes inter e intragrupo. Os resultados que a ausencia de diferencas entre os grupos estudados pode estar relacionada aos efeitos do do TFA realizadopelos HA e IM, comparativamente aos SA