| Autor: |
Weavil JC; Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Salt Lake City, Utah.; Department of Internal Medicine, University of Utah, Salt Lake City, Utah., Thurston TS; Department of Internal Medicine, University of Utah, Salt Lake City, Utah., Hureau TJ; Department of Internal Medicine, University of Utah, Salt Lake City, Utah., Gifford JR; Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Salt Lake City, Utah.; Department of Internal Medicine, University of Utah, Salt Lake City, Utah., Aminizadeh S; Department of Physiology and Pharmacology, Afzalipour School of Medicine, Kerman University of Medical Sciences, Kerman, Iran., Wan HY; Department of Anesthesiology, University of Utah, Salt Lake City, Utah., Jenkinson RH; Department of Anesthesiology, University of Utah, Salt Lake City, Utah., Amann M; Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Salt Lake City, Utah.; Department of Internal Medicine, University of Utah, Salt Lake City, Utah.; Department of Anesthesiology, University of Utah, Salt Lake City, Utah. |
| Abstrakt: |
This study examined the impact of aging on the elastic and resistive components of the work of breathing ( W b ) during locomotor exercise at a given 1 ) ventilatory rate, 2 ) metabolic rate, and 3 ) operating lung volume. Eight healthy younger (25 ± 4 yr) and 8 older (72 ± 6 yr) participants performed incremental bicycle exercise, from which retrospective analyses identified similar ventilatory rates (approximately 40, 70, and 100 L·min -1 ), similar metabolic rates (V̇o 2 : approximately 1.2, 1.6, and 1.9 L·min -1 ), and similar lung volumes [inspiratory and expiratory reserve volumes (IRV/ERV: approximately 25/34%, 16/33%, and 13-34% of vital capacity]. W b at each level was quantified by integrating the averaged esophageal pressure-volume loop, which was then partitioned into elastic and resistive components of inspiratory and expiratory work using the modified Campbell diagram. IRV was smaller in the older participants during exercise at ventilations of 70 and 100 L·min -1 and during exercise at the three metabolic rates ( P < 0.05). Mainly because of a greater inspiratory elastic and resistive W b in the older group ( P < 0.05), total W b was augmented by 40%-50% during exercise at matched ventilatory and matched metabolic rates. When examined during exercise evoking similar lung volumes, total W b was not different between the groups ( P = 0.86). Taken together, although aging exaggerates total W b during locomotor exercise at a given ventilatory or a given metabolic rate, this difference is abolished during exercise at a given operating lung volume. These findings highlight the significance of operating lung volume in determining the age-related difference in W b during locomotor exercise. NEW & NOTEWORTHY This study evaluated the impact of aging on the work of breathing ( W b ) during locomotor exercise evoking similar ventilatory rates, metabolic rates, and operating lung volumes in young and older individuals. Mainly because of a greater inspiratory elastic and resistive W b in older participants, total W b was higher during exercise at any given ventilatory and metabolic rate with aging. However, this age-related difference was abolished during exercise evoking similar operating lung volumes in both age groups. These findings highlight the significance of lung volumes in determining the age-related difference in total W b . |
