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This Article Full Text Full Text (PDF) All Versions of this Article: 287/6/L1098    most recent 00399.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Chaunchaiyakul, R. Articles by Taylor, N. A. S. Search for Related Content PubMed PubMed Citation Articles by Chaunchaiyakul, R. Articles by Taylor, N. A. S.

The impact of aging and habitual physical activity on static respiratory work at rest and during exercise

¹Department of Biomedical Science, University of Wollongong, Wollongong, New South Wales 2522, Australia; ²College of Sports Science and Technology, Mahidol University, Nakonprathom 73170, Thailand; and ³Navy Experimental Diving Unit, Panama City, Florida 32407-7001

Submitted 19 November 2003 ; accepted in final form 28 June 2004

We investigated the effects of aging on the elastic properties of lung tissue and the chest wall, simultaneously quantifying the contribution of each component to static inspiratory muscle work in resting and exercising adults. We further evaluated the interaction of aging and habitual physical activity on respiratory mechanics. Static lung volumes and elastic properties of the lung and chest wall (pressure-volume relaxation maneuvers) in 29 chronically sedentary and 29 habitually active subjects, grouped by age, were investigated: young (Y, 20–30 years), middle-aged (M, 40–50 years), and older (O, >60 years). Using static pressure-volume data, we computed the elastic work of breathing (joules per liter, J·l^–1), including inspiratory muscle work, over resting and exercising tidal volume excursions. Elastic work of the lung (Y = 0.79 ± 0.05; M = 0.47 ± 0.05; O = 0.43 ± 0.05 J·l^–1) and chest wall (Y = –0.49 ± 0.06; M = –0.12 ± 0.07; O = 0.04 ± 0.05 J·l^–1 ) changed significantly with age (P < 0.05). With aging, a parallel displacement of the chest wall pressure-volume curve resulted in a shift from energy being stored primarily during expiration to energy storage during inspiration, and driving expiration, both at rest and during exercise. Although deviating significantly from young adults, this did not significantly elevate static inspiratory muscle work but resulted in a redistribution of the tissues on which this work was performed and the phase of the respiratory cycle in which it occurred. Nevertheless, static inspiratory muscle work remained similar across age groups, at rest and during exercise, and habitual physical activity failed to influence these changes.

chest wall; compliance; respiratory mechanics; work of breathing