ABSTRACT
La respiración es un proceso continuo donde los músculos respiratorios tienen un rol central e imprescindible para la vida. Su óptimo funcionamiento involucra diversas estructuras que deben funcionar de forma armónica y coordinada, para que el gasto energético asociado a sus demandas permita aumentos considerables de carga sin afectar mayormente la función esencial de intercambio gaseoso. Comprender la fisiología muscular, desde la base anatómica hasta su comportamiento en el ejercicio y la enfermedad, es fundamental para detectar con anticipación las diversas disfunciones que se producen cuando este equilibrio se descompensa. El objetivo de esta revisión es entregar las bases fisiológicas del comportamiento de la musculatura respiratoria que permitan comprender y aplicar las mejores estrategias de evaluación y tratamiento, cuando la función normal se ve alterada, ya sea por enfermedad, desuso o altas cargas asociadas al ejercicio físico.
Breathing is a continuous process where the respiratory muscles have a central and essential role for life. Its optimal operation involves various structures that must work in a harmonious and coordinated way, so that the energy expenditure associated with their demands allows considerable increases in load without significantly affecting the essential function of gas exchange. Understanding muscle physiology, from the anatomical basis to its behavior in exercise and disease, is essential to anticipate the various dysfunctions that can occur when this balance is decompensated. The objective of this review is to provide physiological bases for the behavior of the respiratory muscles that allow understanding and applying the best evaluation and treatment strategies, when its correct functioning is altered, either due to illness, disuse or high loads associated with physical exercise.
Subject(s)
Humans , Respiratory Muscles/physiology , Respiratory Physiological Phenomena , Diaphragm/physiologyABSTRACT
The aim of this study was to reveal the mechanism of exaggerated blood pressure rise during resistance exercise. Muscle sympathetic nerve activity (MSNA), heart rate (HR), blood pressure (BP) and grip force were measured during static handgrip exercise. After a 3-minute control period, intermittent static handgrip exercises (10 30-sec contractions with a 30-sec pause between contractions) at 30% of maximum voluntary contraction (HG 30) or with maximum voluntary effort (HGMX) were performed in nine healthy volunteers who gave their consent in advance to participate in this study. In the HG 30 study, MSNA did not increase compared with the control value until the fifth grip exercise, and BP rose during the third HG exercise. HR was elevated in the first grip exercise and remained elevated up to the 10th grip exercise. During HGMX, MSNA, HR and BP increased significantly during the first grip exercise compared to the control rest, and MSNA and BP rose even further as the contractions accumulated; while HR response remained almost constant throughout the contractions. Mean handgrip force decreased progressively with the increasing number of grip exercises.<BR>These results indicate that exaggerated BP rise during static muscle contraction dose not seem to be muscle reflex, at least, during the first several contractions; but rather other factors such as central command or mechanical compression of vessels. However, muscle reflex, for instance metaboor mechanoreflex may contribute to elevated BP when the number of contractions accumulate or muscle fatigue develops.