Efecto de diferentes protocolos de recuperación sobre la función autonómica cardiaca

Introdução: a avaliação da função autonômica cardíaca (FAC) após o teste de esforço (TE) é considerada um preditor poderoso e independente de risco cardiovascular. É escasso o conhecimento da influência de diferentes protocolos de recuperação sobre a FAC após TE em esteira rolante com os voluntários na posição ortostática. Objetivo: comparar a reativação vagal e o grau de modulação global da FAC em dois diferentes protocolos de recuperação, passiva (RP) e ativa (RA), imediatamente após TE submáximo em esteira rolante. Métodos: foram avaliados 24 homens fisicamente ativos com idade (média ± DP) de 27,2 ± 4,4 anos e IMC 24,8 ± 1,8 kg/m2. A ordem dos protocolos de recuperação foi definida de forma aleatória. Os testes foram realizados com intervalo de sete dias. Ambas as recuperações foram realizadas na posição ortostática durante cinco minutos, imediatamente após TE. Os índices temporais da variabilidade da frequência cardíaca foram utilizados para avaliar a reativação vagal e o grau de modulação global de FAC, rMSSD e SDNN, respectivamente, na RP e RA. Após análise da distribuição dos dados, utilizaram-se os testes de Mann-Whitney e de Friedman com post-hoc de Dum, no nível de significância de p ≤ 0,05. Resultados: verificou-se maior reativação vagal no primeiro minuto de recuperação na RP comparativamente a RA [4,1 (4,9-3,4) ms vs. 3,4 (4,0-2,9) ms, p = 0,03] e maior grau de modulação global da FAC do terceiro ao quinto minuto e tendência a diferença significativa no segundo minuto de RP comparativamente a RA (p = 0,09-0,005). Conclusão: os achados demonstram que o mínimo esforço físico, como caminhar lentamente sobre a esteira rolante, diminuiu a reativação vagal e o grau de modulação global da FAC após o TE submáximo em homens fisicamente ativos.Introduction: the evaluation of cardiac autonomic function (CAF) after stress test (ST) is considered a powerful and independent predictor of cardiovascular risk. The knowledge about the influence of different recovery protocols on CAF after ST on treadmill with volunteers in standing position is scarce. Objective: to compare the vagal reactivation and the degree of global CAF modulation in two different recovery protocols, passive (PR) vs. active (AR) immediately after submaximal ST in treadmill. Methods: We evaluated 24 physically active males, aged (mean ± SD) 27.2 ± 4.4 years and BMI 24.8 ± 1.8 kg/m2. The order of the recovery protocol was set at random. The tests were performed in 7-day intervals. Both recovery protocols were performed in standing position for 5 minutes, immediately after ST. The time indices of heart rate variability were used to assess the vagal reactivation and the overall degree of CAF, rMSSD, and SDNN, respectively, in PR and AR. After analysis of the data distribution, the Mann-Whitney and Friedman tests with Dum post-hoc were used at a significance level of p ≤ 0.05. Results: we observed a higher vagal reactivation at first minute of the PR compared to AR [4.1 (4.9-3.4) ms vs. 3.4 (4.0-2.9) ms, p = 0.03], and a higher degree of global CAF modulation from the third to the fifth minute and a tendency to significant difference in the second minute of PR compared to AR (p = 0.09−0.005). Conclusion: the findings demonstrate that minimum physical effort, such as walking slowly on a treadmill, decreased the vagal reactivation and the overall modulation degree of CAF after a submaximal ST in physically active men.Introducción: la evaluación de la función autonómica cardíaca (FAC) después de la prueba de esfuerzo (PE) se considera un predictor potente e independiente del riesgo cardiovascular. Es escaso el conocimiento de la influencia de los diferentes protocolos de recuperación sobre la FAC después de la PE en la cinta rodante con voluntarios en la posición de pie. Objetivo: comparar la reactivación vagal y el grado de la modulación general de la FAC en dos diferentes protocolos de recuperación, pasiva (RP) vs. activa (RA) inmediatamente después de la PE submáxima en la cinta rodante. Métodos: se evaluaron 24 hombres físicamente activos con edades (promedio ± DE) de 27,2 ± 4,4 años y IMC de 24,8 ± 1,8 kg/m2. El orden de los protocolos de recuperación se definió al azar. Las pruebas se realizaron en un intervalo de siete días. Ambas recuperaciones se realizaron en la posición de pie durante cinco minutos inmediatamente después de la PE. Los índices temporales de la variabilidad de la frecuencia cardiaca fueron utilizados para evaluar la reactivación vagal y el grado de modulación general de la FAC, rMSSD y SDNN, respectivamente, en RP y RA. Después del análisis de la distribución de los datos, se utilizaron la prueba de Mann-Whitney y la de Friedman con post-hoc de Dum, a un nivel de significación de p ≤ 0,05. Resultados: se observó una mayor reactivación vagal en el primer minuto de la PR comparada a la RA [4,1 (4,9-3,4) ms vs. 3,4 (4,0-2,9) ms, p = 0,03] y un mayor grado de modulación general de la FAC del tercer al quinto minuto y una tendencia a la diferencia estadística en el segundo minuto de RP comparada a RA (p = 0,09-0,005). Conclusión: los resultados muestran que el esfuerzo físico mínimo, como caminar lentamente sobre la cinta rodante, disminuyó la reactivación vagal y el grado de modulación general de la FAC después de la PE submáxima en hombres físicamente activos

Agreement between BMI and body fat obesity definitions in a physically active population

Body mass index (BMI) is a widely used proxy of body composition (BC). Concerns exist regarding possible BMI misclassification among active populations. We compared the prevalence of obesity as categorized by BMI or by skinfold estimates of body fat percentage (BF%) in a physically active population. Subjects and methods 3,822 military firefighters underwent a physical fitness evaluation including cardiorespiratory fitness (CRF) by the 12 min-Cooper test, abdominal strength by sit-up test (SUT) and body composition (BC) by BF% (as the reference), as well as BMI. Obesity was defined by BF% > 25% and BMI ≥ 30 kg/m2. Agreement was evaluated by sensitivity and specificity of BMI, positive and negative predictive values (PPV/NPV), positive and negative likelihood (LR+/LR-), receiver operating characteristic (ROC) curves and also across age, CRF and SUT subgroups. Results The prevalence of obesity estimated by BMI (13.3%) was similar to BF% (15.9%). Overall agreement was high (85.8%) and varied in different subgroups (75.3-94.5%). BMI underestimated the prevalence of obesity in all categories with high specificity (≥ 81.2%) and low sensitivity (≤ 67.0). All indices were affected by CRF, age and SUT, with better sensitivity, NPV and LR- in the less fit and older groups; and higher specificity, PPV and LR+ among the fittest and youngest groups. ROC curves showed high area under the curve (≥ 0.77) except for subjects with CRF ≥ 14 METs (= 0.46). Conclusion Both measures yielded similar obesity prevalences, with high agreement. BMI did not overestimate obesity prevalence. BMI ≥ 30 was highly specific to exclude obesity. Because of systematic under estimation, a lower BMI cut-off point might be considered in this population

NÍVEL DE ATIVIDADE FÍSICA E QUALIDADE DE VIDA DE POLICIAIS

Resumo: Bons níveis de atividade física e qualidade de vida são fatores determinantes para uma condição humana saudável, sendo imprescindível ao âmbito da prática laboral policial. O objetivo deste trabalho foi investigar os níveis de atividade física e de qualidade de vida de policiais militares de um dos estados da região Norte do Brasil. Uma pesquisa epidemiológica realizada com a aplicação do IPAQ e do WHOQOL-Bref. As variáveis foram analisadas por meio de estatística descritiva apresentadas em medidas de tendência central e de dispersão.  Os resultados demonstraram um bom nível de qualidade de vida, com os maiores escores no domínio social e os menores no domínio ambiental. Sobre o nível de atividade física verificou-se que a maioria dos policiais militares pesquisados são ativos fisicamente. Contudo, a análise do IMC apresentou que a maioria dos profissionais pesquisados está classificada como sobrepesados ou obesos. Palavras-chave: Qualidade de Vida. Atividade Física. Policial Militar. Saúde Profissional Abstract: Good levels of physical activity and quality of life are determining factors for a healthy human condition, being essential in the police sphere. The aim of this study was to investigate the levels of physical activity and quality of life of military police officers from one of the states of northern Brazil. An epidemiological research conducted with the application of IPAQ and WHOQOL-Bref. The variables were analyzed using descriptive statistics presented in measures of central tendency and dispersion. The results showed a good quality of life, with the highest scores in the social domain and the lowest in the environmental domain. Regarding the level of physical activity it was found that most of the military police surveyed are physically active. However, BMI analysis showed that most professionals surveyed are classified as overweight or obese. Keywords: Quality of Life. Physical Activity. Military Police. Professional Healt

Impact of heart rate on reproducibility of heart rate variability analysis in the supine and standing positions in healthy men

OBJECTIVE: The reliability of heart rate variability (HRV) analysis is not yet fully understood, especially considering different body positions and the mathematical influence of heart rate. The aim of this study was to evaluate the reliability of HRV in supine and standing positions, with and without mathematical adjustment of HRV by the average R-R interval (iRR). METHODS: We evaluated 37 young males (23.1±4 years; 25.1±3 kg/m2). A 5-min segment of the iRR was collected in the supine and standing positions on three occasions separated by 48-hour intervals. Absolute and relative reliability of temporal and spectral indices were assessed by the coefficient of variation (CV) and the intraclass correlation coefficient (ICC), respectively. RESULTS: We did not observe differences in HRV indices in the three occasions in the supine or standing position (p>0.05). Moderate to good reproducibility was observed for temporal and spectral indices of HRV in the supine position (ICC: 0.65-0.89; CV: 0.9-19.8). In the orthostatic position, low to good reproducibility was observed (ICC: 0.35-0.89; CV: 1.1-34.8), with higher ICCs for temporal indices. After mathematical adjustment, only a small modification in HRV reliability was observed in both positions. CONCLUSIONS: In young adult males, the mathematical adjustment of HRV by the average iRR led to a nonsignificant effect on HRV reliability. Additionally, HRV reliability is dependent on body position and the index analyzed. Promising measures in both supine and standing positions include r-MSSD and the HF band (parasympathetic indices)

Nivel insuficiente de actividad física está asociado a menor calidad de vida y al estudio nocturno en universitarios del Distrito Federal

A prática de atividade física (AF) é essencial à saúde e à qualidade de vida (QV). Objetivo: Avaliar o nível de atividade física (NAF), a QV, fatores antropométricos e socioeconômicos em universitários do Distrito Federal. Métodos: Foram avaliados aleatoriamente 392 voluntários (43,6% homens). Empregaram-se os questionários IPAQ, WHOQOL e de tempo sentado (TS). Foram avaliados preditores do NAF com o emprego de regressão logística, assim como da QV estratificada por sexo, turno, NAF e renda. Resultados: Dos pesquisados, 51,4% eram insuficientemente ativos (IA) e mostraram menor QV do que os ativos (AT), nos domínicos físico (DOMF) e psicológico (DOMPS) (p 0,05). Menor NAF associou-se com maior TS e com aulas no turno noturno. A proporção de universitários IA foi elevada e se mostrou associada com menor QV no DOMF e DOMPS, elevado TS e com estudo noturno.Physical activity (PA) practice is an essential issue for health and quality of life (QOL). Objective: We analyzed the level of physical activity (LPA) and QOL in association with anthropometric and socioeconomics factors among undergraduate students from the Distrito Federal - Brazil. Methods: We randomly evaluated 392 volunteers (43.6% men). We employed the IPAQ + reported siting time (ST), and WHOQOL questionnaires. Logistic regression was used to evaluate LPA predictors. QOL was compared between sex, class period (day vs night), LPA and income. Results: Two hundred and one volunteers (51.4%) were insufficiently active (IA) and showed lower QOL than the active (AT) ones on physical (PHD) and psychological (PSD) domains (p< 0.05). Lower LPA was associated with greater ST and with the night shift study. We found a high proportion of IA students that was associated with lower QOL on PHD and PSD, higher ST and nightshift study

Reliability of heart rate variability threshold and parasympathetic reactivation after a submaximal exercise test

The objective of this study was to evaluate reproducibility of heart rate variability threshold (HRVT) and parasympathetic reactivation in physically active men (n= 16, 24.3 ± 5.1 years). During the test, HRVT was assessed by SD1 and r-MSSD dynamics. Immediately after exercise, r-MSSD was analyzed in segments of 60 seconds for a period of five minutes. High absolute and relatively reproducible analysis of HRVT were observed, as assessed by SD1 and r-MSSD dynamics (ICC = 0.92, CV = 10.8, SEM = 5.8). During the recovery phase, a moderate to high reproducibility was observed for r-MSSD from the first to the fifth minute (ICC = 0.69-0.95, CV = 7.5-14.2, SEM = 0.07-1.35). We conclude that HRVT and r-MSSD analysis after a submaximal stress test are highly reproducible measures that might be used to assess the acute and chronic effects of exercise training on cardiac autonomic modulation during and/or after a submaximal stress test

Efeitos do incremento do número de passos diários sobre a função autonômica cardíaca e o desempenho físico no limiar anaeróbico, em indivíduos normais sedentários

Tese (doutorado)—Universidade de Brasília, Faculdade de Medicina, 2007.Introdução: Promover o estilo de vida ativo tornou-se preocupação central na esfera da saúde pública. Evidências da associação positiva entre atividade física e saúde são abundantes. Entretanto, existem lacunas sobre efeitos de intervenções baseadas no quantitativo de passos diários, bem como de mecanismos fisiológicos implicados. Objetivos: Verificar os efeitos do incremento de 3500 passos diários, durante três semanas, sobre a função autonômica cardíaca (FAC) e o desempenho físico no limiar anaeróbico, em indivíduos normais e insuficientemente ativos. Avaliar a efetividade do aumento do número de passos diários e correlacionar esse incremento com a variabilidade da freqüência cardíaca (VFC) e com variáveis de desempenho físico no limiar anaeróbico (LA). Indivíduos e Métodos: Foram estudados 19 homens, com idade mediana de 30 anos (19 - 46 anos), clinicamente normais, sedentários e com IMC entre 18,5 e 29,9 Kg/m2. Os participantes submeteram-se ao teste de avaliação da FAC, por meio das análises temporal e espectral da VFC de séries temporais de 5 min de intervalos R-R do ECG, obtidos por meio do freqüencímetro Polar S 810®, no repouso supino e na postura ortostática. Seqüencialmente registrou-se o padrão usual de passos diários por ± 18 dias, por meio do pedômetro Yamax SW710® (fase controle). Logo após, submeteram-se a nova avaliação da FAC e ao teste ergoespirométrico (TE) para avaliação do desempenho físico ao nível do LA. Iniciou-se, então, a fase de intervenção com incremento mínimo de 3.500 passos diários durante ± 23 dias, calculado sobre a média de passos diários acumulados em dias de semana na fase controle. Ao término, procedeu-se à nova avaliação da FAC, bem como do desempenho físico no LA. Resultados: A mediana e extremos do número de passos/dia na fase de intervenção (11772, 8998 – 18620) foi superior ao registrado na fase controle (7295, 4700 – 14752) p<0,0001). As variáveis funcionais de repouso (FC, PAS e PAD) e antropométricas (peso e IMC) não se alteraram com a intervenção (p>0,05). A maioria dos índices temporais da VFC ficaram estáveis (p>0,05), à exceção da média dos intervalos R-R (supino e ortostático) e do rMSSD no ortostatismo (p=0,07 – 0,05 e 0,07). Dos índices espectrais, apenas a área espectral de baixa freqüência no supino mostrou tendência estatística de redução (p=0,076). A intervenção provocou aumento do desempenho físico no LA, com incremento médio de 8% na distância percorrida (p=0,02) e de 6% no tempo até o LA (p=0,03), sem, entretanto, modificar o consumo de oxigênio e a FC no LA (p>0,12). Observou-se tendência de correlação positiva entre o incremento percentual de passos e o pNN50 e a área espectral absoluta de baixa freqüência no supino na última avaliação (rs = 0,39 - p = 0,09) e o pNN50 e rMSSD na postura ortostática (rs = 0,44 - p = 0,06). Houve correlação negativa entre a FC de repouso e a variação percentual da FC de repouso até o LA, nos dois testes de esforço (rs = -0,67 e -0,69 respectivamente, p< 0,002). Conclusões: O incremento no número de passos diários induziu discreto aumento da modulação parassimpática, especialmente na postura ortostática, porém sem modificar o balanço vago-simpático. O treinamento físico mostrou-se eficiente para melhorar o rendimento físico submáximo ao nível do limiar anaeróbico. As sutis modificações observadas adquirem relevância, tendo em vista a faixa etária da amostra e o tipo de intervenção instituída, baseada apenas no aumento de passos diários. _______________________________________________________________________________________ ABSTRACTIntroduction: Promoting an active life style has become a central concern in the Public Health sector. Evidences of the positive association between physical activity and health are abundant. Nevertheless, there are gaps on the effects of interventions based on the amount of daily steps, as well as in what concerns the physiological mechanisms involved. Objectives: To verify the effects of the increase of 3500 daily steps, during a three week period on the cardiac autonomic function (CAF) and the physical performance at the anaerobic threshold (AT), in normal and inactive subjects. To evaluate the effectiveness of increasing the number of daily steps and to corrolate this increase to the heart rate variability (HRV) and to the variables of physical performance at the AT. Subjects and Methods: Nineteen men, with median age of 30 years old (19-46 years), clinically normal, sedentary and with BMI between 18.5 and 29.9 Kg/m2 were studied. The participants were submitted to CAF assessment test through temporal and spectral analysis of HRV in 5 minute temporal series of R-R intervals of ECG, obtained from the Polar S810® heart rate monitor, in supine rest and in orthostatic posture. Following that, the usual pattern of daily steps was recorded for ± 18 days, using SW710® Yamax Pedometer (control stage). Right after, they were submitted to a new CAF assessment and to a cardiopulmonary exercise test (CET) in order to assess physical performance at the AT. Intervention stage was then started with a minimum increase of 3500 daily steps, during ± 23 days, increase which was calculated on the mean number of daily steps accumulated during week days in the control stage. At the end, a new CAF assessment was performed as well as a new cardiopulmonary exercise test. Results: The median and the extremes of number of steps/day during the intervention stage (11772, 8998 – 18620) were higher than those recorded in the control stage (7295, 4700 – 14752). Functional variables (HR, SBP and DBP) and anthropometric variables of rest (weight and BMI) were not altered by the intervention (p>0.05). Most temporal indexes of HRV remained stable (p>0.05), except for the mean of R-R intervals (supine and orthostatic) and of rMSSD on orthostatism (p=0.07 – 0.05 e 0.07). Among the spectral indexes, only the spectral area of low frequency on supine showed a statistic tendency to reduction (p=0.076). The intervention caused an increase in physical performance at the AT, with an average increase of 8% in the covered distance (p=0.02) and of 6% in time until AT, not modifying, however, the oxygen consumption and the heart rate (HR) at the AT (p=0.12). A tendency of positive correlation between the percental increase of steps and pNN50 and the absolute spectral area of low frequency on supine in the last evaluation (rs = 0.39 - p = 0.09) and the pNN50 and the rMSSD in orthostatic posture was observed. There was a negative correlation between the HR at rest and the percentual variation of HR at rest until AT, in two effort tests (rs = -0.67 and -0.69 respectively, p< 0.002). Conclusions: The increase in number of daily steps led to a slight increase in parasympathetic modulation, especially in orthostatic posture, though with no change to the sympathovagal balance. Physical training proved efficient in improving sub maximum physical performance at the anaerobic threshold. The subtle changes observed become important, when bearing in mind the age scope of the sample and the type of intervention used, which was based only on the increase of daily steps

Can resting heart rate explain the heart rate and parasympathetic responses during rest, exercise, and recovery?

The effect of resting heart rate (RHR) on the heart rate (HR) dynamics and parasympathetic modulation at rest, exercise, and recovery remain to be clarified. This study compares HR and parasympathetic responses at rest, during submaximal exercise testing and recovery in young, physically active men with different RHR average values. HR and parasympathetic responses were compared between two groups: bradycardia group–RHR < 60 bpm (BG, n = 20) and normocardia group–RHR ≥ 60 ≤ 100 bpm (NG, n = 20). A Polar RS800® was used to record the RR-interval series and HR at rest in the supine position, following the postural change (from supine to orthostatic position) and in the orthostatic position for 5 minutes, as well as during and after a submaximal exercise testing. Statistical analysis employed the MANOVA, Mann-Whitney, and Simple Linear regression test with a two-tailed p-value set at ≤ 0.05. BG at rest showed lower HR in the orthostatic position, higher parasympathetic activity in the supine and orthostatic positions, and higher parasympathetic reactivity than NG (p ≤ 0.01) after the postural change. BG before exercise showed lower HR and higher values of the chronotropic reserve and parasympathetic withdrawal than NG (p ≤ 0.01) throughout the exercise. Following the exercise, BG showed higher values of HR recovery (HRR) and parasympathetic reactivation in the 3rd and 5th minutes of recovery than NG (p ≤ 0.01). Lastly, the RHR can explain the variance of the HR at rest, during exercise testing, and recovery from 11 to 48%. We concluded that BG (RHR < 60 bpm) showed higher chronotropic and parasympathetic modulation at rest, higher chronotropic reserve, parasympathetic withdrawal during the submaximal exercise test, and faster HRR and parasympathetic reactivation after effort in young physically active men