title: Effect of weight loss on operational lung volumes and oxygen cost of breathing in obese women.
abstract: The effects of moderate weight loss on operational lung volumes during exercise and the oxygen (O2) cost of breathing are unknown in obese women but could have important implications regarding exercise endurance.
  
  
  
  In 29 obese women (33±8 years, 97±14 kg, body mass index: 36±4 kg m(-2), body fat: 45.6±4.5%; means±s.d.), body composition, fat distribution (by magnetic resonance imaging), pulmonary function, operational lung volumes during exercise and the O2 cost of breathing during eucapnic voluntary hyperpnea (([Vdot ]O2) vs ([Vdot ]E) slope) were studied before and after a 12-week diet and resistance exercise weight loss program.
  
  
  
  Participants lost 7.5±3.1 kg or ≈8% of body weight (P<0.001), but fat distribution remained unchanged. After weight loss, lung volume subdivisions at rest were increased (P<0.05) and were moderately associated (P<0.05) with changes in weight. End-expiratory lung volume (percentage of total lung capacity) increased at rest and during constant load exercise (P<0.05). O2 cost of breathing was reduced by 16% (2.52±1.02-2.11±0.72 ml l(-1); P=0.003). As a result, O2 uptake of the respiratory muscles ([Vdot ]O2Resp), estimated as the product of O2 cost of breathing and exercise ([Vdot ]E) during cycling at 60 W, was significantly reduced by 27±31 ml (P<0.001), accounting for 46% of the reduction in total body ([Vdot ]O2) during cycling at 60 W.
  
  
  
  Moderate weight loss yields important improvements in respiratory function at rest and during submaximal exercise in otherwise healthy obese women. These changes in breathing load could have positive effects on the exercise endurance and adherence to physical activity.
authors: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center, Dallas, TX, USA.|Exercise Physiology Program, College of Nursing and Health Sciences, Valdosta State University, Valdosta, GA, USA.
authors: D M
authors: DM
authors: Bhammar
authors: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center, Dallas, TX, USA.|Health and Exercise Science, Appalachian State University, Boone, NC, USA.
authors: J L
authors: JL
authors: Stickford
authors: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center, Dallas, TX, USA.|Department of Health and Human Performance, Texas A&M University-Commerce, Commerce, TX, USA.
authors: V
authors: V
authors: Bernhardt
authors: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center, Dallas, TX, USA.
authors: T G
authors: TG
authors: Babb
mesh_terms: D000328:Adult; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005652:Functional Residual Capacity / Q000502:physiology; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology*; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D010101:Oxygen Consumption / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D055070:Resistance Training; D014109:Total Lung Capacity / Q000502:physiology; D015431:Weight Loss / Q000502:physiology*; D061217:Weight Reduction Programs