Coupling of dyspnea perception and occurrence of tachypnea during exercise.
During exercise, tidal volume initially contributes to ventilatory responses more than respiratory frequency, and respiratory frequency then increases rapidly while tidal volume stabilizes. Dyspnea intensity is also known to increase in a threshold-like manner. We tested the possibility that the threshold of tachypneic breathing is equal to that of dyspnea perception during cycle ergometer exercise (n = 27). Dyspnea intensity was scored by a visual analog scale. Thresholds were expressed as values of pulmonary O2uptake at each breakpoint. Dyspnea intensity and respiratory frequency started increasing rapidly once the intensity of stimuli exceeded a threshold level. The thresholds for dyspnea intensity and for occurrence of tachypnea were significantly correlated. An intraclass correlation coefficient of 0.71 and narrow limits of agreement on the Bland-Altman plot indicated a good agreement between these thresholds. These results suggest that the start of tachypneic breathing coincides with the threshold for dyspnea intensity during cycle ergometer exercise.
Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.|Department of Neurology, Showa University School of Medicine, Tokyo, Japan.
Setsuro
S
Tsukada
Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.
Yuri
Y
Masaoka
Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.
Akira
A
Yoshikawa
Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.
Keiji
K
Okamoto
Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.
Ikuo
I
Homma
Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan. masahiko@med.showa-u.ac.jp.
Masahiko
M
Izumizaki
D004417:Dyspnea / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010465:Perception / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology; D056152:Respiratory Rate / Q000502:physiology*; D059246:Tachypnea / Q000503:physiopathology*; D013990:Tidal Volume / Q000502:physiology; D055815:Young Adult
Dyspnea; Exercise hyperpnea; Pulmonary O2 uptake; Respiratory frequency; Tachypnea