Validação do teste de exercício de 4 segundos em posição ortostática

Abstract

160Cardiovascular diseases are the major cause of mortality in Brazil, accounting for 32% of all recorded deaths and 10% of all hospital admissions in 2000 1 . The risk of several cardiovascular events increases many times due to autonomic dysfunction, frequently caused by a reduction in parasympathetic activity 2 , which is a strong and independent indicator of a negative prognosis 3 both in individuals with heart failure 4,5 and after infarction 6 , and even in the general population 7 .There are several valid procedures to investigate the autonomic condition of an individual, providing relevant clinical or physiological contributions, or both [8][9][10] , among which the 4-second exercise test (4sET), originally proposed by Araújo et al 11 , stands out. The 4sET is based on eliminating the vagal cardiac tonus in the first seconds of rapid exercise involving large muscle groups. The 4sET is a pharmacologically validated autonomic test, whose finality is the isolated analysis of the vagal modulation of heart rate in the initial transient of dynamic exercise 12 . Since it was reported, 4sET has been applied in the clinical area in some sports medicine and cardiology laboratories, in addition to being used as an instrument of scientific investigation in the research developed by our group 11,13-18 and also by other research centers 19 .Despite the simplicity and low cost of the 4sET, and the easy interpretation of its results, the need for a cycloergometer remains a limitation for the broader use of the test according to the original protocol. Considering that a cycloergometer is not frequently found in specialized laboratories and clinics for exercise testing, it is necessary to analyze the possibility of performing 4sET under more appropriate conditions. This study aimed to test the operational viability of the 4sET performed in the orthostatic position without an ergometer and to validate a 4sET protocol. MethodsThe study comprised 47 adults of both sexes (40±17 years, 169±9 cm, 72±14 kg) with different clinical conditions, who randomly underwent 3 consecutive repetitions of 4sET in the 2 protocols suggested as follows: 1) the CYCLO protocol using a cycloergometer, according to the original 4sET 12 ; and 2) the alternative ORTHO protocol, with 4sET performed in the orthostatic position. The first repetition in each protocol served to acquaint the individuals with the procedures, and the best result of the last 2 repetitions was considered to represent the vagal cardiac index of the individual. All participants signed the written consent before the tests. The protocol and the study design were approved by the institution. 0.84, 0.85, and 0.93, respectively (P<0.001). Original Article Validation of the 4-Second Exercise Test in the Orthostatic Position ConclusionThe 4sET performed in the orthostatic position proved to be a valid option for assessing the vagal cardiac tonus in laboratories lacking a cycloergometer, without jeopardizing clinical interpretation. In addition to simplicity and applicability, the pr...

Respostas hemodinâmicas a um protocolo de treinamento isométrico de preensão manual

“…Although hemodynamic responses were observed as a result of IHT performed in this study, the small magnitude of the differences between the resting conditions and the end of the exercise suggests a minimal or likely negligible clinical significance, representing less than the variation observed during a walk or even a fast riding exercise without load 38 .…”

Correlação entre atividade vagal cardíaca e capacidade funcional em indivíduos com doença arterial periférica

“…Para realização do teste foi usada uma bicicleta ergométrica, sem carga e com cilindro que permitia ajuste de altura. Após adaptação do participante na bicicleta foram dadas as instruções para realização do teste, sendo definidas basicamente em quatro comandos: a) puxar o ar rápido e de forma profunda; b) no 4º segundo pedalar rápido e forte; c) no 8º segundo parar de pedalar; d) no 12º soltar o ar 15 . O cálculo do IVC foi realizado conforme demonstrado na Figura 1 16 .…”

“…O cálculo do IVC considera a razão entre o RRB, que é o intervalo RR imediatamente antes da realização do exercício ou o imediatamente após o início, sempre considerando o mais longo, e o RRC, que é o intervalo mais curto durante a realização do exercício, comumente o último antes da finalização do exercício 15 . Os valores de referência do IVC são estabelecidos de acordo com a faixa etária 17 .…”

Normotensos com resposta pressórica exagerada ao exercício possuem tônus vagal cardíaco aumentado

“…The assessment of the CVT by the 4sET is based on the reflex physiological response of vagal withdrawal, induced by rapid limb movement and cortical irradiation. The assessment of the CVT by the 4sET is reproducible 13 and was pharmacologically validated for the isolated assessment of the parasympathetic component 14 , having been previously used in several physiological autonomic [15][16][17][18] and clinical studies by our group [19][20][21][22] and by other authors 23,24 . For the CVI measurement, two specific R-R intervals were identified and measured from digital electrocardiographic records (Elite PC, Micromed, Brazil), obtained from a single lead (CC 5 or CM 5 ) with 10-ms resolution, as follows: a) the RR interval obtained immediately before or the first one after the start of exercise, whichever is the longest and b) the shortest R-R interval (RRC) during the 4-s exercise (usually, the last one) 20,25 .…”