B-15 Thematic Poster - Advances in Epidemiology

Abstract

BACKGROUND: The effect of weight loss on lung function at rest in men and women is well documented. Weight loss also improves breathing mechanics during exercise in obese men. However, the effect of weight loss on breathing mechanics during exercise is unknown in obese women, who have smaller respiratory reserves than obese men. PURPOSE: To investigate the effects of weight loss on breathing mechanics during submaximal exercise in obese women. We hypothesized that weight loss would improve breathing mechanics during submaximal exercise via an increase in end-expiratory lung volume (EELV). METHODS: In 29 obese women (age: 33 ± 8 y, weight: 96.8 ± 14.0 kg, BMI: 36.2 ± 3.5 kg/m2, percent body fat: 45.6 ± 4.5%; Mean ± SD), body composition, fat distribution (MRI), pulmonary function, and breathing mechanics during exercise were studied before and after a 12-week diet and resistance exercise weight loss program. Data were analyzed by paired t-tests. Relationships among variables were investigated by Pearson’s correlations. RESULTS: Subjects lost 7.5 ± 3.1 kg of body weight (P < 0.001). Total lung capacity, functional residual capacity (FRC), and expiratory reserve volume were significantly increased (4.8 ± 0.7 to 4.9 ± 0.8 L, 2.0 ± 0.4 to 2.2 ± 0.5 L, 0.8 ± 0.3 to 1.1 ± 0.5 L respectively; P < 0.05) while inspiratory capacity was decreased (2.8 ± 0.5 to 2.7 ± 0.5 L; P < 0.05) after weight loss. Changes in FRC were moderately associated with changes in body weight, BMI, abdominal fat and total chest fat + abdominal fat (r = -0.58 to -0.65; P < 0.05). EELV increased at rest (42.7 ± 7.5 to 45.7 ± 7.6 %TLC; P = 0.004) and during constant load exercise (40.4 ± 5.1 to 42.5 ± 5.7 %TLC; P = 0.02). There was no significant association between the increase in EELV with weight loss and the magnitude of expiratory flow limitation. There were no meaningful correlations between the changes in EELV during constant load exercise and changes in body composition or pulmonary function. CONCLUSIONS: Moderate weight loss improves breathing mechanics not only at rest but also during submaximal exercise in obese women, which is clinically important since submaximal exercise is a major component in the treatment and prevention of obesity. FUNDING SOURCES: NIH R01 HL096782-01A2, King Charitable Foundation Trust, Texas Health Presbyterian Hospital Dallas