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Original Research: PULMONARY PHYSIOLOGY |

Weight Loss via Diet and Exercise Improves Exercise Breathing Mechanics in Obese MenWeight Loss Improves Exercise Breathing Mechanics FREE TO VIEW

Tony G. Babb, PhD; Brenda L. Wyrick, BSN; Paul J. Chase, MEd; Darren S. DeLorey, PhD; Susan G. Rodder, MS; Mabel Y. Feng, MS; Kamalini G. Ranasinghe, MD
Author and Funding Information

From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and the University of Texas Southwestern Medical Center, Dallas, TX.

Correspondence to: T. G. Babb, PhD, Institute for Exercise and Environmental Medicine, 7232 Greenville Ave, Ste 435, Dallas, TX 75231; e-mail: TonyBabb@TexasHealth.org


Funding/Support: This work was supported by an ALA Career Investigator Award, the King Charitable Foundation, the Cain Foundation, and Texas Health Presbyterian Hospital Dallas.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).


© 2011 American College of Chest Physicians


Chest. 2011;140(2):454-460. doi:10.1378/chest.10-1088
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Published online

Background:  Obesity alters breathing mechanics during exercise. Weight loss improves lung function at rest, but the effect of weight loss, especially regional fat loss, on exercise breathing mechanics is unclear. We hypothesized that weight loss, especially a decrease in abdominal fat, would improve breathing mechanics during exercise because of an increase in end-expiratory lung volume (EELV).

Methods:  Nine obese men were studied before and after weight loss (13% ± 8% of total fat weight, mean ± SD). Subjects underwent pulmonary function testing, underwater weighing, fat distribution estimates (MRI), and graded cycle ergometry before and after a 12-week diet and exercise program. In seven men, esophageal and gastric pressures were measured. The effects of weight loss were analyzed at rest, at ventilatory threshold (VTh), and during peak exercise by dependent Student t test, and the relationship among variables was determined by correlation analysis.

Results:  Subjects lost 7.4 ± 4.2 kg of body weight (P < .001), but the distribution of fat remained unchanged. After weight loss, lung volume subdivisions at rest were increased (P < .05) and were moderately associated (P < .05) with changes in chest, waist, and hip circumferences. At VTh, EELV increased, and gastric pressure decreased significantly (P < .05). The changes in waist circumference, hip circumference, BMI, and sum of chest, waist, and hip circumferences were also consistently and significantly correlated (P < .05) with changes in gastric pressure during exercise at VTh.

Conclusions:  Modest weight loss improves breathing mechanics during submaximal exercise in otherwise healthy obese men, which is clinically encouraging. Improvement appears to be related to the cumulative loss of chest wall fat.

Figures in this Article

Breathing mechanics during exercise are significantly altered in obesity. Compared with normal-weight adults, obese individuals breathe at lower lung volumes; have elevated respiratory pressures, an increased work of breathing, and increased breathlessness; and experience greater expiratory flow limitation and hyperinflation at peak exercise.1-3 The effect of weight loss on resting lung function is well known.4-10 Also, the negative influence of fat distribution on resting lung function has been shown by both indirect11-14 and direct assessment of fat distribution.15 However, the effect of weight loss, in particular regional fat loss, on breathing mechanics during exercise is unclear. For example, it is unknown if weight loss that improves lung function at rest also improves breathing mechanics during exercise. In prior work, we have shown that factors other than passive weight-related mechanical forces on the chest wall (ie, rib cage and abdomen) also influence the end-expiratory lung volume (EELV) adopted during exercise in obese men and women.1,2 Also, it is uncertain if improvement in breathing mechanics during exercise depends primarily on the loss of chest wall fat. To investigate this, we studied obese men before and after weight loss. Weight loss was accomplished via a 12-week diet and general exercise program. We hypothesized that weight loss would improve breathing mechanics during exercise because of an increase in EELV, and that individuals with abdominal (subcutaneous or visceral) fat loss would have the greatest changes in breathing mechanics during exercise. The data contained in this article have been published previously in abstract form.16,17

Subjects

Written informed consent was obtained before participation (University of Texas Southwestern institutional review board approval no. 0195 00100). Volunteers were screened by BMI and brief medical history. Obesity was confirmed by underwater weighing (30 ≤ % body fat ≤ 52). No subject had a history of smoking, asthma, cardiovascular disease, or musculoskeletal abnormalities that would preclude maximal exercise testing, or had participated in regular vigorous exercise for the previous 6 months. After initial screening, the participants returned for exercise testing and for the measurement of fat distribution by MRI.

The subjects were recruited through local advertisements. Twelve subjects were enrolled for study. One subject did not meet study inclusion criteria and another subject dropped out in the first week of training because of a change in his work schedule. One subject dropped out of the study midway through the weight-loss program because of personal reasons. This left nine subjects who completed testing before and after the 12-week diet and exercise weight-loss program.

Body Composition

Height, weight, and circumference measurements (chest, waist, and hip) were made, and underwater weighing (for percent body fat, lean body mass, and total body fat mass) was carried out. These measurements were undertaken to characterize changes (if any) in body size among the subjects.

Pulmonary Function

All subjects had standard spirometry and lung volume determinations (model 6200 body plethysmograph; SensorMedics; Yorba Linda, California) according to American Thoracic Society guidelines.18 Predicted values for spirometry and lung volumes were based on the norms of Knudson et al,19,20 and Goldman and Becklake,21 respectively.

Gas Exchange and Breathing Mechanics During Exercise

Cardiorespiratory measurements and breathing mechanics were determined during graded cycle ergometry to exhaustion, as described previously.22 After 3 min of baseline measurements, the subjects performed graded cycle ergometry on an electronically braked cycle ergometer (model CPE 2000; MedGraphics; St. Paul, Minnesota). Exercise began at 30 W and was increased by 30 W each minute until volitional exhaustion or pedal rate ≤ 50 rpm. ECG (Model CS 100; Schiller; Baar, Switzerland), heart rate, BP (Suntech 4240; Raleigh, North Carolina), ratings of perceived breathlessness (Borg 0-10 scale), ratings of perceived exertion (Borg 6-20 scale), pulmonary gas exchange (minute ventilation, oxygen uptake, and CO2 output), end-tidal Pco2, and pulse oximetry (arterial oxygen saturation, forehead probe) were monitored during exercise. Ventilatory threshold (VTh) was determined from the comparison of gas exchange indexes23 and the V-slope method.24 VTh was designated as the work rate most congruent among the different threshold determination methods, as described previously.1,2

In addition, breathing mechanics were measured to characterize changes (if any) in breathing pattern, tidal flow-volume patterns, lung volume, and respiratory pressures at rest and during exercise after weight loss. Inspiratory capacity (IC) was measured at rest and during exercise to determine placement of tidal flow-volume loops within the maximal flow-volume loop, as described previously.22,25 EELV was estimated from measurement of IC and total lung capacity (TLC) as measured in the body plethysmograph (EELV = TLC − IC) and reported as a percentage of TLC ([EELV/TLC] × 100).26 End-inspiratory lung volume was calculated as EELV + tidal volume (Vt) and expressed as a percentage of TLC. Maximal flow-volume loops were determined at rest and within 2 min following termination of exercise to determine if exercise had induced bronchodilation or bronchoconstriction, which none of the subjects experienced. Respiratory pressures (pleural; transpulmonary [Ptp]; and gastric [Pga]) were used for estimating the mechanical work of breathing and the magnitude of breathing effort with inspiration and expiration.

Fat Distribution

Multiple MRI scans through the chest and abdomen were used to estimate subcutaneous chest fat, abdominal fat (which was divided into anterior subcutaneous abdominal fat and visceral fat), posterior subcutaneous fat, and peripheral fat (total body fat minus chest, posterior, and abdominal fat).15 MRI data were obtained in all volunteers using a whole-body magnet, as previously described.15,27 Images were analyzed manually with the use of software by Scion Image (version β 4.0.2; Scion Corp; Frederick, Maryland).15,27-29 This method has been described previously,30-33 and the data were similar to those produced by comparable MRI techniques.28,34,35

12-Week Diet and Exercise Program

All tests were repeated after a supervised 12-week diet and exercise weight-loss program. Each participant received dietary counseling and an individualized diet program from a registered dietician. The participants also received an exercise prescription consisting of specific aerobic and resistive exercises, which were monitored 2 days per week. The exercise was used to increase caloric expenditure only, rather than to produce an improvement in exercise endurance. The participants were encouraged to lose 1 to 2 pounds per week and to complete both aerobic and resistive exercises each week to limit loss of muscle mass during the program. They had full access to the fitness center for exercise during the 12-week program. The subjects were very compliant with the exercise part of the program.

Data Analysis

The mechanical work of breathing against the lung was estimated per breath from the area enclosed by the dynamic tidal pressure-volume loop (ie, using Ptp) with the addition of that portion of a triangle describing work that fell outside the tidal pressure-volume loop (ie, part of inspiratory elastic work), and then averaged.36 Also calculated was expiratory airflow limitation, defined as the percentage of Vt (% Vt) where tidal expiratory flow impinged on maximal expiratory flow.22,25 Data were analyzed at rest, at VTh, and during peak exercise.

Differences after weight loss were tested by dependent Student t test. Because of the small sample size, we did not conduct formal tests for normality of the data. Visual inspection of plotted data did not reveal any material departure from normality, so we used paired Student t tests to compare means. Relationships among variables were determined with Pearson correlation coefficients. A P value < .05 was considered significant.

Body Composition and Fat Distribution

Nine men completed the study (37 ± 5 y and 179 ± 3 cm). The subjects lost 7.4 ± 4.2 kg of body weight and 5.9 ± 3.6 kg of fat weight (13% ± 8% of total fat) (P < .001). The subjects lost significant amounts of regional fat as well, but fat distribution (% of total fat) remained unchanged, with the exception of a small change in anterior subcutaneous abdominal fat (Fig 1, Table 1).

Figure Jump LinkFigure 1. Fat distribution (kilograms and % fat weight) before and after a 12-week diet and exercise weight-loss program in obese men. Data are presented as mean ± SD. Ant Sub Q = anterior subcutaneous abdominal fat; Post Sub Q = posterior subcutaneous fat; Peripheral = fat not on the chest wall.Grahic Jump Location
Table Graphic Jump Location
Table 1 —Body Composition Before and After 12-Week Weight-Loss Program (N = 9)

Data are presented as mean ± SD. Chest = circumference at chest; Hip = circumference at hip; LBM = lean body mass; ns = nonsignificant; PBF = percent body fat; Waist = circumference at waist; Waist/Hip ratio = ratio of waist circumference to hip circumference; Wt = weight.

Pulmonary Function

Resting FVC (Table 2), functional residual capacity (FRC), and expiratory reserve volume were increased significantly (P < .05) after weight loss (Fig 2). These changes in lung volume subdivisions were moderately associated (P < .05) with changes in waist, hip, and the sum of chest, waist, and hip circumferences, but not with individual changes in regional fat, chest wall fat, or total body weight.

Table Graphic Jump Location
Table 2 —Pulmonary Function: Spirometry (N = 9)

Data are presented as mean ± SD. % pred = percent predicted; PEF = peak expiratory flow; RV = residual volume; TLC = total lung capacity. See Table 1 for expansion of other abbreviations.

a 

n = 8.

Figure Jump LinkFigure 2. Lung volumes (% TLC) before and after a 12-week diet and exercise weight-loss program in obese men. Data are presented as mean ± SD. *P < .05. ERV = expiratory reserve volume; FRC = functional residual capacity; RV = residual volume; % TLC = percent total lung capacity.Grahic Jump Location
Peak Exercise Capacity

The focus of the exercise component of the weight-loss program was to increase energy expenditure, not to improve aerobic capacity. No training workloads or heart rates were assigned to the subjects. Thus, during peak exercise there were only small increases in peak exercise time and peak work rate after completing the exercise and weight-loss program (P < .05) (data not shown). Peak oxygen uptake (% predicted) was normal in the obese men before and after initiating the weight-loss program (ie, normal exercise capacity), with no significant ventilatory limitations.

Breathing Mechanics at Rest and During Exercise

At VTh, EELV was increased significantly (P < .05) after weight loss (Fig 3). Few of the changes in resting Ptp (ie, end-inspiratory, end-expiratory, and peak expiratory pressure) were significant after weight loss and none was significant during exercise at VTh or peak exercise after weight loss. There were no significant changes in the mechanical work of breathing against the lung with weight loss. However, Pga was reduced significantly (P < .05) after weight loss at rest and during exercise at VTh (Fig 4). Prior to weight loss, none of the men had expiratory flow limitation at rest, two had it during exercise at VTh (3% ± 6% of Vt, mean ± SD), and seven had it at peak exercise (18% ± 13%). After weight loss, none had expiratory flow limitation at rest, only one had it at VTh (2% ± 5%), and six had it at peak exercise (11% ± 11%, P = .09).

Figure Jump LinkFigure 3. EELV (% TLC) at rest and during exercise before and after a 12-week diet and exercise weight-loss program. Data are presented as mean ± SD. *P < .05. EELV = end-expiratory lung volume; V˙ e = minute ventilation; VTh = ventilatory threshold. See Figure 2 legend for expansion of other abbreviations.Grahic Jump Location
Figure Jump LinkFigure 4. Pga at end inspiration, peak expiration, and end expiration (cm H2O) at rest and during exercise before and after a 12-week diet and exercise weight-loss program. Data are presented as mean ± SD. *P < .05; **P < .01; bn = 8; cn = 7. Pga = gastric pressure. See Figure 3 legend for expansion of other abbreviations.Grahic Jump Location

The changes in Pga during exercise at VTh were consistently and significantly correlated (P < .05) with changes in BMI, waist circumference, hip circumference, and the sum of chest, waist, and hip circumferences, but not with changes in regional fat or total body weight (data not shown). The association between the change in peak expiratory Pga at VTh and the change in the sum of chest, waist, and hip circumference was quite strong (r = 0.91, P < .01) (Fig 5).

Figure Jump LinkFigure 5. Association between the change in peak expiratory Pga at the VTh and the change in the sum of chest, waist, and hip circumferences. See Figure 3 and 4 legends for expansion of abbreviations.Grahic Jump Location

The results of this study demonstrated that moderate weight loss can improve obesity-related alterations in breathing mechanics during exercise in otherwise healthy, moderately obese men via an increase in EELV. Also, it appears that it is the cumulative loss of overall chest wall fat that is important to the changes in lung function during exercise, rather than changes in any specific region of fat (chest, subcutaneous abdominal, or visceral fat).

Body Composition and Fat Distribution

The subjects in this study lost approximately 7% of their body weight and 14% of their fat weight. These changes in body composition are in agreement with the findings of other studies of mildly to extremely obese men5,37,38 and women39,40 who participated in similar diet and/or exercise programs. Despite a significant loss in body fat, fat distribution was not altered, thus confirming the conventional thinking that weight lost occurs evenly over the entire body, not preferentially from any particular body region. The participants lost 2.51 ± 1.70 kg of fat weight from the chest wall (∼ 12% of fat weight) (P < .01).

Pulmonary Function

The improvement in resting pulmonary function was also consistent with the findings reported by other studies.5,7,41 Basically, our subjects were able to increase their FVC and lung volume subdivisions, especially FRC, which is sensitive to weight on the chest wall.42 The change in expiratory reserve volume with weight loss was due to an increase in both FVC and FRC. Although the change in FVC was small, it played an important role in increasing expiratory Vt reserve (ie, reserve for decreasing EELV during exercise).43,44 The reductions in respiratory pressures at rest, namely Pga, reflect the increase in FRC and imply a decrease in the impedance to the downward displacement of the diaphragm.1

Notably, the changes in lung function were not significantly associated with changes in regional fat, total fat, total body weight, or total chest wall fat. However, the changes in body circumferences, especially the change in the sum of chest, abdominal, and hip circumferences, were significantly associated with the increase in FRC. It appears that it is the cumulative effect of overall chest wall size that is important to changes in resting lung function in moderately obese men, rather than changes in any specific regional chest wall fat.15

Breathing Mechanics During Exercise

Modest weight loss appears to improve breathing mechanics during exercise, as evidenced by the increase in EELV (ie, return to a more normal position) during submaximal exercise and the decrease in Pga seen throughout the breathing cycle. It was unclear if weight loss would also change the lung volume adopted during exercise, because chest wall weight and other unknown factors appear to influence EELV during cycling exercise in obese adults.1,2 The improvement in EELV (ie, less reduction in EELV) during exercise places the tidal flow-volume loop in a better position within the maximal flow-volume loop to minimize the potential risk of developing expiratory flow limitation during exercise.43,45 The higher EELV at peak exercise after weight loss may have contributed to the minor decrease in expiratory flow limitation. The increase in EELV also implies a downward displacement of the diaphragm at end-expiration. This new position places the diaphragm at a more mechanically advantageous length, which should improve inspiratory diaphragm function.46-48

The reduction in respiratory pressures during exercise is consistent with prior findings1,2 and suggests that the increase in EELV is beneficial with regard to respiratory effort generated during exercise,1 especially Pga (ie, work to displace abdomen downward). The rise in EELV from VTh to peak exercise is also consistent with prior studies on respiratory mechanics in obese men or women,1,2,49 and indicates the presence of mechanical respiratory constraints (ie, expiratory flow limitation, hyperinflation, end-inspiratory lung volume nearing TLC, and so forth) during heavy exercise in obese men.1 It is unknown whether greater or continued weight loss would further increase or normalize EELV during exercise in obese men.

Therefore, weight loss via diet and exercise appears to influence the EELV adopted during submaximal exercise. This influence is not specific to any special regional change in fat weight. We propose that it is the cumulative effect of chest wall fat that influences the EELV adopted during exercise,15 along with other obesity-related mechanical ventilatory constraints (ie, respiratory muscle recruitment patterns, respiratory afferents, expiratory flow limitation, work of breathing, and so forth).1,2

Limitations

The detailed testing of the subjects (ie, pulmonary function, exercise testing, MRI, respiratory mechanics, including esophageal and gastric balloons during exercise) before and after a 12-week diet and exercise weight-loss program limited the number of subjects able and willing to participate in the study. Therefore, the number of subjects is lower than preferred and may reduce the generalization of the findings, especially to those with extreme obesity.

In conclusion, moderate weight loss via a 12-week diet and exercise program can significantly improve breathing mechanics during exercise in otherwise healthy obese men. This is an encouraging finding for obese men who must tolerate and engage in regular exercise for the prevention and treatment of obesity and other obesity-related comorbidities. Also, the increase in EELV during exercise with weight loss appears to be related to the cumulative loss of chest wall fat rather than to changes in any specific regional fat measurement.

Author contributions:Dr Babb: contributed to designing the project, supervising data collection, assisting in data collection, directing data processing and analysis, and writing of the manuscript.

Ms Wyrick: contributed to planning the project, subject recruitment, data collection, MRI analyses, and editorial comments on the manuscript.

Mr Chase: contributed to data collection, data processing and analysis, and editorial comments on the manuscript.

Dr DeLorey: contributed to data collection, data processing and analysis, critical input, and development of the manuscript.

Ms Rodder: contributed to the design of the diet and exercise program, counseling subjects, critical input regarding the study logistics, and editorial comments on the manuscript.

Ms Feng: contributed to data processing and analysis, important input to the MRI data analysis, and editorial comments on the manuscript.

Dr Ranasinghe: contributed to data collection, data processing and analysis, critical input on statistical analysis, and development of the manuscript.

Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Role of sponsors: The sponsors had no role in the design of the study, the collection and analysis of the data, or in the preparation of the manuscript.

Other contributions: The authors thank J. L. Barron and the staff members of the Presbyterian CVC Better Weigh Program for their assistance in various stages of this project. The authors also express their appreciation to T. Tillery, RT (R)(MR)(CT), B. Fox, RT (R)(MR), J. Payne, PA-C, and P. T. Weatherall, MD, of the Rogers Center at the University of Texas Southwestern for their assistance with this project.

EELV

end-expiratory lung volume

FRC

functional residual capacity

IC

inspiratory capacity

Pga

gastric pressure

Ptp

transpulmonary pressure

TLC

total lung capacity

Vt

tidal volume

VTh

ventilatory threshold

DeLorey DS, Wyrick BL, Babb TG. Mild-to-moderate obesity: implications for respiratory mechanics at rest and during exercise in young men. Int J Obes (Lond). 2005;299:1039-1047. [CrossRef] [PubMed]
 
Babb TG, DeLorey DS, Wyrick BL, Gardner PP. Mild obesity does not limit change in end-expiratory lung volume during cycling in young women. J Appl Physiol. 2002;926:2483-2490. [PubMed]
 
Babb TG, Buskirk ER, Hodgson JL. Exercise end-expiratory lung volumes in lean and moderately obese women. Int J Obes. 1989;131:11-19. [PubMed]
 
Aaron SD, Fergusson D, Dent R, Chen Y, Vandemheen KL, Dales RE. Effect of weight reduction on respiratory function and airway reactivity in obese women. Chest. 2004;1256:2046-2052. [CrossRef] [PubMed]
 
Womack CJ, Harris DL, Katzel LI, Hagberg JM, Bleecker ER, Goldberg AP. Weight loss, not aerobic exercise, improves pulmonary function in older obese men. J Gerontol A Biol Sci Med Sci. 2000;558:M453-M457. [CrossRef] [PubMed]
 
Carey IM, Cook DG, Strachan DP. The effects of adiposity and weight change on forced expiratory volume decline in a longitudinal study of adults. Int J Obes Relat Metab Disord. 1999;239:979-985. [CrossRef] [PubMed]
 
De Lorenzo A, Petrone-De Luca P, Sasso GF, Carbonelli MG, Rossi P, Brancati A. Effects of weight loss on body composition and pulmonary function. Respiration. 1999;665:407-412. [CrossRef] [PubMed]
 
Wise RA, Enright PL, Connett JE, et al. Effect of weight gain on pulmonary function after smoking cessation in the Lung Health Study. Am J Respir Crit Care Med. 1998;1573 Pt 1:866-872. [PubMed]
 
Sue DY. Obesity and pulmonary function: more or less? Chest. 1997;1114:844-845. [CrossRef] [PubMed]
 
Vaughan RW, Cork RC, Hollander D. The effect of massive weight loss on arterial oxygenation and pulmonary function tests. Anesthesiology. 1981;544:325-328. [CrossRef] [PubMed]
 
Canoy D, Luben R, Welch A, et al. Abdominal obesity and respiratory function in men and women in the EPIC-Norfolk Study, United Kingdom. Am J Epidemiol. 2004;15912:1140-1149. [CrossRef] [PubMed]
 
Lazarus R, Gore CJ, Booth M, Owen N. Effects of body composition and fat distribution on ventilatory function in adults. Am J Clin Nutr. 1998;681:35-41. [PubMed]
 
Lazarus R, Sparrow D, Weiss ST. Effects of obesity and fat distribution on ventilatory function: the normative aging study. Chest. 1997;1114:891-898. [CrossRef] [PubMed]
 
Collins LC, Hoberty PD, Walker JF, Fletcher EC, Peiris AN. The effect of body fat distribution on pulmonary function tests. Chest. 1995;1075:1298-1302. [CrossRef] [PubMed]
 
Babb TG, Wyrick BL, DeLorey DS, Chase PJ, Feng MY. Fat distribution and end-expiratory lung volume in lean and obese men and women. Chest. 2008;1344:704-711. [CrossRef] [PubMed]
 
Babb TG, Wyrick BL, Chase PJ, et al. Effects of weight loss on fat distribution and exercise mechanics in obese men. Med Sci Sports Exerc. 2003;355:S229
 
Babb TG, DeLorey DS, Wyrick BL, Chase PJ, Feng MY, Barron JL. Effects of fat distribution on lung volume in obese men. Med Sci Sports Exerc. 2002;345:S19. [CrossRef]
 
American Thoracic SocietyAmerican Thoracic Society Standardization of spirometry, 1994 update. Am J Respir Crit Care Med. 1995;1523:1107-1136. [PubMed]
 
Knudson RJ, Lebowitz MD, Holberg CJ, Burrows B. Changes in the normal maximal expiratory flow-volume curve with growth and aging. Am Rev Respir Dis. 1983;1276:725-734. [PubMed]
 
Knudson RJ, Slatin RC, Lebowitz MD, Burrows B. The maximal expiratory flow-volume curve. Normal standards, variability, and effects of age. Am Rev Respir Dis. 1976;1135:587-600. [PubMed]
 
Goldman HI, Becklake MR. Respiratory function tests; normal values at median altitudes and the prediction of normal results. Am Rev Tuberc. 1959;794:457-467. [PubMed]
 
Babb TG. Ventilation and respiratory mechanics during exercise in younger subjects breathing CO2or HeO2. Respir Physiol. 1997;1091:15-28. [CrossRef] [PubMed]
 
Caiozzo VJ, Davis JA, Ellis JF, et al. A comparison of gas exchange indices used to detect the anaerobic threshold. J Appl Physiol. 1982;535:1184-1189. [PubMed]
 
Sue DY, Wasserman K, Moricca RB, Casaburi R. Metabolic acidosis during exercise in patients with chronic obstructive pulmonary disease. Use of the V-slope method for anaerobic threshold determination. Chest. 1988;945:931-938. [CrossRef] [PubMed]
 
Babb TG. Ventilatory response to exercise in subjects breathing CO2or HeO2J Appl Physiol. 1997;823:746-754. [PubMed]
 
Bae J, Ting EY, Giuffrida J. The effect of changes in the body position of obese patients on pulmonary volume and ventilation function. Bull N Y Acad Med. 1976;527:830-837. [PubMed]
 
Babb TG, Ranasinghe KG, Comeau LA, Semon TL, Schwartz B. Dyspnea on exertion in obese women: association with an increased oxygen cost of breathing. Am J Respir Crit Care Med. 2008;1782:116-123. [CrossRef] [PubMed]
 
Thomas EL, Saeed N, Hajnal JV, et al. Magnetic resonance imaging of total body fat. J Appl Physiol. 1998;855:1778-1785. [PubMed]
 
Perry AC, Applegate EB, Jackson ML, et al. Racial differences in visceral adipose tissue but not anthropometric markers of health-related variables. J Appl Physiol. 2000;892:636-643. [PubMed]
 
Abate N, Garg A, Coleman R, Grundy SM, Peshock RM. Prediction of total subcutaneous abdominal, intraperitoneal, and retroperitoneal adipose tissue masses in men by a single axial magnetic resonance imaging slice. Am J Clin Nutr. 1997;652:403-408. [PubMed]
 
Abate N, Garg A, Peshock RM, Stray-Gundersen J, Adams-Huet B, Grundy SM. Relationship of generalized and regional adiposity to insulin sensitivity in men with NIDDM. Diabetes. 1996;4512:1684-1693. [CrossRef] [PubMed]
 
Abate N, Garg A, Peshock RM, Stray-Gundersen J, Grundy SM. Relationships of generalized and regional adiposity to insulin sensitivity in men. J Clin Invest. 1995;961:88-98. [CrossRef] [PubMed]
 
Abate N, Burns D, Peshock RM, Garg A, Grundy SM. Estimation of adipose tissue mass by magnetic resonance imaging: validation against dissection in human cadavers. J Lipid Res. 1994;358:1490-1496. [PubMed]
 
Ross R, Léger L, Morris D, de Guise J, Guardo R. Quantification of adipose tissue by MRI: relationship with anthropometric variables. J Appl Physiol. 1992;722:787-795. [PubMed]
 
Kamel EG, McNeill G, Van Wijk MCW. Usefulness of anthropometry and DXA in predicting intra-abdominal fat in obese men and women. Obes Res. 2000;81:36-42. [CrossRef] [PubMed]
 
McGregor M, Becklake MR. The relationship of oxygen cost of breathing to respiratory mechanical work and respiratory force. J Clin Invest. 1961;40:971-980. [CrossRef] [PubMed]
 
Kraemer WJ, Volek JS, Clark KL, et al. Influence of exercise training on physiological and performance changes with weight loss in men. Med Sci Sports Exerc. 1999;319:1320-1329. [CrossRef] [PubMed]
 
Katzel LI, Bleecker ER, Colman EG, Rogus EM, Sorkin JD, Goldberg AP. Effects of weight loss vs aerobic exercise training on risk factors for coronary disease in healthy, obese, middle-aged and older men. A randomized controlled trial. JAMA. 1995;27424:1915-1921. [CrossRef] [PubMed]
 
Utter AC, Nieman DC, Shannonhouse EM, Butterworth DE, Nieman CN. Influence of diet and/or exercise on body composition and cardiorespiratory fitness in obese women. Int J Sport Nutr. 1998;83:213-222. [PubMed]
 
Kraemer WJ, Volek JS, Clark KL, et al. Physiological adaptations to a weight-loss dietary regimen and exercise programs in women. J Appl Physiol. 1997;831:270-279. [PubMed]
 
Ray CS, Sue DY, Bray GA, Hansen JE, Wasserman K. Effects of obesity on respiratory function. Am Rev Respir Dis. 1983;1283:501-506. [PubMed]
 
Wang LY, Cerny FJ. Ventilatory response to exercise in simulated obesity by chest loading. Med Sci Sports Exerc. 2004;365:780-786. [CrossRef] [PubMed]
 
Babb TG. Mechanical ventilatory constraints in aging, lung disease, and obesity: perspectives and brief review. Med Sci Sports Exerc. 1999;31suppl1:S12-S22. [CrossRef] [PubMed]
 
Babb TG, Rodarte JR. Estimation of ventilatory capacity during submaximal exercise. J Appl Physiol. 1993;744:2016-2022. [PubMed]
 
Ferretti A, Giampiccolo P, Cavalli A, Milic-Emili J, Tantucci C. Expiratory flow limitation and orthopnea in massively obese subjects. Chest. 2001;1195:1401-1408. [CrossRef] [PubMed]
 
Martin JG, DeTroyer A. The Thorax and Control of Functional Residual Capacity. The Thorax. 1985; New York, NY Dekker:899-921
 
Agostoni E, Hyatt RE. Static behavior of the respiratory system. Handbook of Physiology. 1986; Bethesda, MD: American Physiology Society:113-130
 
Palecek F. Hyperinflation: control of functional residual lung capacity. Physiol Res. 2001;503:221-230. [PubMed]
 
Ofir D, Laveneziana P, Webb KA, O’Donnell DE. Ventilatory and perceptual responses to cycle exercise in obese women. J Appl Physiol. 2007;1026:2217-2226. [CrossRef] [PubMed]
 

Figures

Figure Jump LinkFigure 1. Fat distribution (kilograms and % fat weight) before and after a 12-week diet and exercise weight-loss program in obese men. Data are presented as mean ± SD. Ant Sub Q = anterior subcutaneous abdominal fat; Post Sub Q = posterior subcutaneous fat; Peripheral = fat not on the chest wall.Grahic Jump Location
Figure Jump LinkFigure 2. Lung volumes (% TLC) before and after a 12-week diet and exercise weight-loss program in obese men. Data are presented as mean ± SD. *P < .05. ERV = expiratory reserve volume; FRC = functional residual capacity; RV = residual volume; % TLC = percent total lung capacity.Grahic Jump Location
Figure Jump LinkFigure 3. EELV (% TLC) at rest and during exercise before and after a 12-week diet and exercise weight-loss program. Data are presented as mean ± SD. *P < .05. EELV = end-expiratory lung volume; V˙ e = minute ventilation; VTh = ventilatory threshold. See Figure 2 legend for expansion of other abbreviations.Grahic Jump Location
Figure Jump LinkFigure 4. Pga at end inspiration, peak expiration, and end expiration (cm H2O) at rest and during exercise before and after a 12-week diet and exercise weight-loss program. Data are presented as mean ± SD. *P < .05; **P < .01; bn = 8; cn = 7. Pga = gastric pressure. See Figure 3 legend for expansion of other abbreviations.Grahic Jump Location
Figure Jump LinkFigure 5. Association between the change in peak expiratory Pga at the VTh and the change in the sum of chest, waist, and hip circumferences. See Figure 3 and 4 legends for expansion of abbreviations.Grahic Jump Location

Tables

Table Graphic Jump Location
Table 1 —Body Composition Before and After 12-Week Weight-Loss Program (N = 9)

Data are presented as mean ± SD. Chest = circumference at chest; Hip = circumference at hip; LBM = lean body mass; ns = nonsignificant; PBF = percent body fat; Waist = circumference at waist; Waist/Hip ratio = ratio of waist circumference to hip circumference; Wt = weight.

Table Graphic Jump Location
Table 2 —Pulmonary Function: Spirometry (N = 9)

Data are presented as mean ± SD. % pred = percent predicted; PEF = peak expiratory flow; RV = residual volume; TLC = total lung capacity. See Table 1 for expansion of other abbreviations.

a 

n = 8.

References

DeLorey DS, Wyrick BL, Babb TG. Mild-to-moderate obesity: implications for respiratory mechanics at rest and during exercise in young men. Int J Obes (Lond). 2005;299:1039-1047. [CrossRef] [PubMed]
 
Babb TG, DeLorey DS, Wyrick BL, Gardner PP. Mild obesity does not limit change in end-expiratory lung volume during cycling in young women. J Appl Physiol. 2002;926:2483-2490. [PubMed]
 
Babb TG, Buskirk ER, Hodgson JL. Exercise end-expiratory lung volumes in lean and moderately obese women. Int J Obes. 1989;131:11-19. [PubMed]
 
Aaron SD, Fergusson D, Dent R, Chen Y, Vandemheen KL, Dales RE. Effect of weight reduction on respiratory function and airway reactivity in obese women. Chest. 2004;1256:2046-2052. [CrossRef] [PubMed]
 
Womack CJ, Harris DL, Katzel LI, Hagberg JM, Bleecker ER, Goldberg AP. Weight loss, not aerobic exercise, improves pulmonary function in older obese men. J Gerontol A Biol Sci Med Sci. 2000;558:M453-M457. [CrossRef] [PubMed]
 
Carey IM, Cook DG, Strachan DP. The effects of adiposity and weight change on forced expiratory volume decline in a longitudinal study of adults. Int J Obes Relat Metab Disord. 1999;239:979-985. [CrossRef] [PubMed]
 
De Lorenzo A, Petrone-De Luca P, Sasso GF, Carbonelli MG, Rossi P, Brancati A. Effects of weight loss on body composition and pulmonary function. Respiration. 1999;665:407-412. [CrossRef] [PubMed]
 
Wise RA, Enright PL, Connett JE, et al. Effect of weight gain on pulmonary function after smoking cessation in the Lung Health Study. Am J Respir Crit Care Med. 1998;1573 Pt 1:866-872. [PubMed]
 
Sue DY. Obesity and pulmonary function: more or less? Chest. 1997;1114:844-845. [CrossRef] [PubMed]
 
Vaughan RW, Cork RC, Hollander D. The effect of massive weight loss on arterial oxygenation and pulmonary function tests. Anesthesiology. 1981;544:325-328. [CrossRef] [PubMed]
 
Canoy D, Luben R, Welch A, et al. Abdominal obesity and respiratory function in men and women in the EPIC-Norfolk Study, United Kingdom. Am J Epidemiol. 2004;15912:1140-1149. [CrossRef] [PubMed]
 
Lazarus R, Gore CJ, Booth M, Owen N. Effects of body composition and fat distribution on ventilatory function in adults. Am J Clin Nutr. 1998;681:35-41. [PubMed]
 
Lazarus R, Sparrow D, Weiss ST. Effects of obesity and fat distribution on ventilatory function: the normative aging study. Chest. 1997;1114:891-898. [CrossRef] [PubMed]
 
Collins LC, Hoberty PD, Walker JF, Fletcher EC, Peiris AN. The effect of body fat distribution on pulmonary function tests. Chest. 1995;1075:1298-1302. [CrossRef] [PubMed]
 
Babb TG, Wyrick BL, DeLorey DS, Chase PJ, Feng MY. Fat distribution and end-expiratory lung volume in lean and obese men and women. Chest. 2008;1344:704-711. [CrossRef] [PubMed]
 
Babb TG, Wyrick BL, Chase PJ, et al. Effects of weight loss on fat distribution and exercise mechanics in obese men. Med Sci Sports Exerc. 2003;355:S229
 
Babb TG, DeLorey DS, Wyrick BL, Chase PJ, Feng MY, Barron JL. Effects of fat distribution on lung volume in obese men. Med Sci Sports Exerc. 2002;345:S19. [CrossRef]
 
American Thoracic SocietyAmerican Thoracic Society Standardization of spirometry, 1994 update. Am J Respir Crit Care Med. 1995;1523:1107-1136. [PubMed]
 
Knudson RJ, Lebowitz MD, Holberg CJ, Burrows B. Changes in the normal maximal expiratory flow-volume curve with growth and aging. Am Rev Respir Dis. 1983;1276:725-734. [PubMed]
 
Knudson RJ, Slatin RC, Lebowitz MD, Burrows B. The maximal expiratory flow-volume curve. Normal standards, variability, and effects of age. Am Rev Respir Dis. 1976;1135:587-600. [PubMed]
 
Goldman HI, Becklake MR. Respiratory function tests; normal values at median altitudes and the prediction of normal results. Am Rev Tuberc. 1959;794:457-467. [PubMed]
 
Babb TG. Ventilation and respiratory mechanics during exercise in younger subjects breathing CO2or HeO2. Respir Physiol. 1997;1091:15-28. [CrossRef] [PubMed]
 
Caiozzo VJ, Davis JA, Ellis JF, et al. A comparison of gas exchange indices used to detect the anaerobic threshold. J Appl Physiol. 1982;535:1184-1189. [PubMed]
 
Sue DY, Wasserman K, Moricca RB, Casaburi R. Metabolic acidosis during exercise in patients with chronic obstructive pulmonary disease. Use of the V-slope method for anaerobic threshold determination. Chest. 1988;945:931-938. [CrossRef] [PubMed]
 
Babb TG. Ventilatory response to exercise in subjects breathing CO2or HeO2J Appl Physiol. 1997;823:746-754. [PubMed]
 
Bae J, Ting EY, Giuffrida J. The effect of changes in the body position of obese patients on pulmonary volume and ventilation function. Bull N Y Acad Med. 1976;527:830-837. [PubMed]
 
Babb TG, Ranasinghe KG, Comeau LA, Semon TL, Schwartz B. Dyspnea on exertion in obese women: association with an increased oxygen cost of breathing. Am J Respir Crit Care Med. 2008;1782:116-123. [CrossRef] [PubMed]
 
Thomas EL, Saeed N, Hajnal JV, et al. Magnetic resonance imaging of total body fat. J Appl Physiol. 1998;855:1778-1785. [PubMed]
 
Perry AC, Applegate EB, Jackson ML, et al. Racial differences in visceral adipose tissue but not anthropometric markers of health-related variables. J Appl Physiol. 2000;892:636-643. [PubMed]
 
Abate N, Garg A, Coleman R, Grundy SM, Peshock RM. Prediction of total subcutaneous abdominal, intraperitoneal, and retroperitoneal adipose tissue masses in men by a single axial magnetic resonance imaging slice. Am J Clin Nutr. 1997;652:403-408. [PubMed]
 
Abate N, Garg A, Peshock RM, Stray-Gundersen J, Adams-Huet B, Grundy SM. Relationship of generalized and regional adiposity to insulin sensitivity in men with NIDDM. Diabetes. 1996;4512:1684-1693. [CrossRef] [PubMed]
 
Abate N, Garg A, Peshock RM, Stray-Gundersen J, Grundy SM. Relationships of generalized and regional adiposity to insulin sensitivity in men. J Clin Invest. 1995;961:88-98. [CrossRef] [PubMed]
 
Abate N, Burns D, Peshock RM, Garg A, Grundy SM. Estimation of adipose tissue mass by magnetic resonance imaging: validation against dissection in human cadavers. J Lipid Res. 1994;358:1490-1496. [PubMed]
 
Ross R, Léger L, Morris D, de Guise J, Guardo R. Quantification of adipose tissue by MRI: relationship with anthropometric variables. J Appl Physiol. 1992;722:787-795. [PubMed]
 
Kamel EG, McNeill G, Van Wijk MCW. Usefulness of anthropometry and DXA in predicting intra-abdominal fat in obese men and women. Obes Res. 2000;81:36-42. [CrossRef] [PubMed]
 
McGregor M, Becklake MR. The relationship of oxygen cost of breathing to respiratory mechanical work and respiratory force. J Clin Invest. 1961;40:971-980. [CrossRef] [PubMed]
 
Kraemer WJ, Volek JS, Clark KL, et al. Influence of exercise training on physiological and performance changes with weight loss in men. Med Sci Sports Exerc. 1999;319:1320-1329. [CrossRef] [PubMed]
 
Katzel LI, Bleecker ER, Colman EG, Rogus EM, Sorkin JD, Goldberg AP. Effects of weight loss vs aerobic exercise training on risk factors for coronary disease in healthy, obese, middle-aged and older men. A randomized controlled trial. JAMA. 1995;27424:1915-1921. [CrossRef] [PubMed]
 
Utter AC, Nieman DC, Shannonhouse EM, Butterworth DE, Nieman CN. Influence of diet and/or exercise on body composition and cardiorespiratory fitness in obese women. Int J Sport Nutr. 1998;83:213-222. [PubMed]
 
Kraemer WJ, Volek JS, Clark KL, et al. Physiological adaptations to a weight-loss dietary regimen and exercise programs in women. J Appl Physiol. 1997;831:270-279. [PubMed]
 
Ray CS, Sue DY, Bray GA, Hansen JE, Wasserman K. Effects of obesity on respiratory function. Am Rev Respir Dis. 1983;1283:501-506. [PubMed]
 
Wang LY, Cerny FJ. Ventilatory response to exercise in simulated obesity by chest loading. Med Sci Sports Exerc. 2004;365:780-786. [CrossRef] [PubMed]
 
Babb TG. Mechanical ventilatory constraints in aging, lung disease, and obesity: perspectives and brief review. Med Sci Sports Exerc. 1999;31suppl1:S12-S22. [CrossRef] [PubMed]
 
Babb TG, Rodarte JR. Estimation of ventilatory capacity during submaximal exercise. J Appl Physiol. 1993;744:2016-2022. [PubMed]
 
Ferretti A, Giampiccolo P, Cavalli A, Milic-Emili J, Tantucci C. Expiratory flow limitation and orthopnea in massively obese subjects. Chest. 2001;1195:1401-1408. [CrossRef] [PubMed]
 
Martin JG, DeTroyer A. The Thorax and Control of Functional Residual Capacity. The Thorax. 1985; New York, NY Dekker:899-921
 
Agostoni E, Hyatt RE. Static behavior of the respiratory system. Handbook of Physiology. 1986; Bethesda, MD: American Physiology Society:113-130
 
Palecek F. Hyperinflation: control of functional residual lung capacity. Physiol Res. 2001;503:221-230. [PubMed]
 
Ofir D, Laveneziana P, Webb KA, O’Donnell DE. Ventilatory and perceptual responses to cycle exercise in obese women. J Appl Physiol. 2007;1026:2217-2226. [CrossRef] [PubMed]
 
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