Sliwiński P, Yan S, Gauthier A P, Macklem P T
Kliniki Chorób Płuc, Instytut Gruźlicy, Warszawa.
Pneumonol Alergol Pol. 1996;64(9-10):590-603.
We evaluated the effect of global inspiratory muscle fatigue (GF) on respiratory muscle control during exercise at 30%, 60%, and 90% of maximal power output in normal subjects. Fatigue was induced by breathing against a high inspiratory resistance until exhaustion. Respiratory pressures, breathing pattern, and perceived breathlessness were measured. Induction of GF had no effect on the ventilatory parameters during mild and moderate exercise. It altered, however, ventilatory response to heavy exercise by increasing breathing frequency and minute ventilation, with minor changes in tidal volume. This was accompanied by an increase in perceived breathlessness. GF significantly increased both the tonic and phasic activities of abdominal muscles that allowed 1) the diaphragm to maintain its function while developing less pressure, 2) the same tidal volume with lesser shortening of the rib cage inspiratory muscles, and 3) relaxation of the abdominal muscles to contribute to lung inflation. The increased work performed by the abdominal muscles may, however, lead to a reduction in their strength. GF may impair exercise performance in some healthy subjects that is probably not related to excessive breathlessness or other ventilatory factors. The respiratory system is remarkably adaptable in maintaining ventilation during exercise even with impaired inspiratory muscle contractility.
我们评估了在正常受试者中，全身性吸气肌疲劳（GF）对运动时呼吸肌控制的影响，运动强度分别为最大输出功率的30%、60%和90%。通过对抗高吸气阻力呼吸直至力竭来诱发疲劳。测量呼吸压力、呼吸模式和主观呼吸困难程度。GF的诱发对轻度和中度运动期间的通气参数没有影响。然而，它通过增加呼吸频率和分钟通气量改变了对剧烈运动的通气反应，潮气量有轻微变化。这伴随着主观呼吸困难程度的增加。GF显著增加了腹肌的紧张性和相位性活动，从而使得：1）膈肌在产生较小压力的同时维持其功能；2）在胸腔吸气肌缩短较少的情况下维持相同的潮气量；3）腹肌放松有助于肺充气。然而，腹肌所做的额外功可能会导致其力量下降。GF可能会损害一些健康受试者的运动表现，这可能与过度呼吸困难或其他通气因素无关。即使吸气肌收缩力受损，呼吸系统在运动期间维持通气方面仍具有显著的适应性。
