Paper
International Journal of Obesity (2005) 29, 1039–1047. doi:10.1038/sj.ijo.0803003; published online 24 May 2005
Mild-to-moderate obesity: implications for respiratory mechanics at rest and during exercise in young men
D S DeLorey1, B L Wyrick1 and T G Babb1,2
- 1Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, TX, USA
- 2The University of Texas Southwestern Medical Center, Dallas, TX, USA
Correspondence: Dr TG Babb, Institute for Exercise, and Environmental Medicine, 7232 Greenville Ave, Ste 435, Dallas, TX 75231, USA. E-mail: TonyBabb@TexasHealth.org
Received 24 June 2004; Revised 3 November 2004; Accepted 4 November 2004; Published online 24 May 2005.
Abstract
OBJECTIVE:
To investigate the effect of mild-to-moderate obesity on respiratory mechanics at rest and during exercise in obese men. We hypothesized that the simple mass loading of obesity would alter both end-expiratory lung volume (EELV) and respiratory pressures (gastric, Pga and transpulmonary, PTP) in resting body positions and during graded cycle ergometry to exhaustion.
SUBJECTS:
A total of 10 obese (38
5% body fat; means.d.) and nine lean (184%) men were studied.
METHODS:
Body composition (by body circumferences and hydrostatic weighing) and pulmonary function were measured at rest. Breathing mechanics were measured at rest in the upright-seated position, supine, and during cycling exercise. Data were analyzed by independent t-test.
RESULTS:
EELV was significantly lower in the obese men in the supine (304 vs 376% total lung capacity (TLC)) and seated (396 vs 475%TLC) positions and at ventilatory threshold (355 vs 457%TLC) (P<0.01). In contrast, at peak exercise, EELV was not different between groups. Respiratory pressures (Pga and PTP) were elevated (P<0.05) during one or more phases of the breathing cycle at rest and during exercise in obese men.
CONCLUSION:
These data demonstrate that mild-to-moderate obesity in young men results in reduced lung volumes and alterations in respiratory mechanics when supine, seated at rest, and during exercise. During moderate exercise, obesity does not appear to limit changes in EELV; however, the regulation of EELV during heavy exercise appears to be affected.
Keywords:
ventilation, control of breathing, lung volumes, pulmonary function, exercise
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