Flow Limitation and Regulation of Functional Residual Capacity during Exercise in a Physically Active Aging Population

作者：Bruce D. Johnson, William G. Reddan, David F. Pegelow, Khiang C. Seow, Jerome A. Dempsey · 发表于：American Review of Respiratory Disease · 年份：1991 · DOI：10.1164/ajrccm/143.5_pt_1.960 · 被引用次数：168 · 研究领域：Chronic Obstructive Pulmonary Disease (COPD) Research、Inhalation and Respiratory Drug Delivery、Respiratory Support and Mechanisms

Abstract In 29 older (69 ± 1 yr), physically active subjects (O2max = 44 ± 2 ml·kg−1·min−1), we determined the effect of an age-related decline in elastic lung recoil (i.e., max50 = 65% of 30-yr-old adults) on the ventilatory response to progressive exercise. More specifically, we assessed if expiratory airflow limits were achieved and how this may modulate the regulation of end-expiratory lung volume (EELV). We found that with only mild to moderate (50 to 75% O2max) exercise, the mean EELV was reduced 0.38 ± 0.07 L, and that expiratory flow limitation was present over 25 ± 4% of the Vt. In 11 subjects during this intensity of exercise, EELV was within their closing capacity. As exercise intensity progressed, Vt plateaued at 58 ± 2% of the vital capacity, and increased expiratory air flow rates were achieved by significantly increasing the EELV back to near resting levels, thereby moving a portion of the expiratory tidal flow-volume envelope away from the constraints of the effort independent portion of the maximal flow-volume curve. During heavy exercise, end-inspiratory lung volume (EILV) approached 90% of TLC. To achieve greater expiratory flow with maximal exercise, EELV remained similar to the previous intensity, and a significantly greater portion of the tidal expiratory flow-volume envelope (> 40% of the Vt) became flow-limited. Despite this significant expiratory limitation, a rise in EELV, and an EILV approaching TLC, Ti/Ttot remained constant throughout exercise, an...