On the Fractal Nature of Breath-by-Breath Variation in Ventilation during Dynamic Exercise
Ventilation (V-̇E) during rest and moderate levels of exercise is tightly coupled to the production of carbon dioxide (V-̇CO2) (13). This is true not only in the steady state, but also in the transient phase between work rates (13). To explain this coupling, the possible roles of carotid and central chemoreceptors, of central motor cortex irradiation, of skeletal muscle mechano- and/or metabolic receptors, and of cardiac or pulmonary mechanoreceptors have been explored (13). This stimulus-based approach to the study of respiratory control omits, as stated by Grodins and Yamashiro (4), the neural control of breathing pattern. Thus, it is important to consider the interaction of these stimuli that regulate the magnitude of the ventilatory response in conjunction with the mechanisms that produce the oscillatory pattern of respiration (3, 4).
KeywordsFractal Dimension Heart Rate Variability Spectral Power Work Rate Breathing Pattern
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