title: [Physiological mechanisms limiting external respiratory resistance].
abstract: A study was performed on 8 healthy male subjects to investigate the effect of nonelastic resistance 6-40 GPa (the air flow velocity being 90 l/min) on the duration of proprioceptive reflexes of respiratory muscles, volume and velocity parameters of forced exhalation. Resistances of 15 and 25 GPa combined with a workload of 100-150 W increased the duration of proprioceptive reflexes from 0.18 +/- 0.015 to 0.29 +/- 0.012 sec and to 0.38 +/- 0.06 sec, respectively, which indicates fatigue of respiratory muscles. Resistance of 25 GPa reduced significantly (by 55%) the maximum volume velocity of forced exhalation and increased its duration by 31%, the exhalation volume decreasing insignificantly (by 6%). The major factor limiting man's tolerance to external respiration resistance is functional deficiency of proprioceptive regulation of respiration and strength and velocity of respiratory muscles.
mesh_terms: D000293:Adolescent; D000328:Adult; D003964:Diaphragm / Q000294:innervation*; D005080:Exercise Test; D006801:Humans; D007366:Intercostal Muscles / Q000294:innervation*; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D011434:Proprioception; D012123:Pulmonary Ventilation; D012018:Reflex / Q000502:physiology*; D012119:Respiration
vernacular_title: O fiziologicheskikh mekhanizmakh, limitiruiushchikh vneshnee soprotivlenie dykhaniiu.