Physical activity and physical function changes in obese individuals after gastric bypass surgery

Surgery for Obesity and Related Diseases 6 (2010) 361–366

Original article

Physical activity and physical function changes in obese individuals after gastric bypass surgery Deborah A. Josbeno, M.S., P.T.a, John M. Jakicic, Ph.D.b, Andrea Hergenroeder, M.P.T.a, George M. Eid, M.D.c,d a Department of Physical Therapy, University of Pittsburgh, Pittsburgh, Pennsylvania Department of Health and Physical Activity, University of Pittsburgh, Pittsburgh, Pennsylvania c Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania d Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania Received May 12, 2008; revised July 17, 2008; accepted August 5, 2008

b

Abstract

Background: Little is known about the effects of gastric bypass surgery (GBS) on physical activity and physical function. We examined the physical activity, physical function, psychosocial correlates to physical activity participation, and health-related quality of life of patients before and after GBS. Methods: A total of 20 patients were assessed before and 3 months after GBS. Physical activity was assessed using the 7-day physical activity recall questionnaire and a pedometer worn for 7 days. Physical function was assessed using the 6-minute walk test, Short Physical Performance Battery, and the physical function subscale of the Medical Outcomes Short Form-36 (SF-36). The Physical Activity Self-Efficacy questionnaire, the Physical Activity Barriers and Outcome Expectations questionnaire, the SF-36, and the Numeric Pain Rating Scale were also administered. Results: Physical activity did not significantly increase from before (191.1 ⫾ 228.23 min/wk) to after (231.7 ⫾ 230.04 min/wk) GBS (n ⫽ 18); however, the average daily steps did significantly increase (from 4621 ⫾ 3701 to 7370 ⫾ 4240 steps/d; n ⫽ 11). The scores for the 6-minute walk test (393 ⫾ 62.08 m to 446 ⫾ 41.39 m; n ⫽ 17), Short Physical Performance Battery (11.2 ⫾ 1.22 to 11.7 ⫾ .57; n ⫽ 18), physical function subscale of the SF-36 (65 ⫾ 18.5 to 84.1 ⫾ 19.9), and the total SF-36 (38.2 ⫾ 23.58 to 89.7 ⫾ 15.5; n ⫽ 17) increased significantly. The Numeric Pain Rating Scale score decreased significantly for low back (3.5 ⫾ 1.8 to 1.7 ⫾ 2.63), knee (2.4 ⫾ 2.51 to 1.0 ⫾ 1.43), and foot/ankle (2.3 ⫾ 2.8 to 0.9 ⫾ 2.05) pain. No significant changes were found in the Physical Activity Self-Efficacy questionnaire or the Physical Activity Barriers and Outcome Expectations questionnaire. Conclusion: GBS improves physical function, health-related quality of life, and self-reported pain and results in a modest improvement in physical activity. These are important clinical benefits of surgical weight loss. Long-term follow-up is needed to quantify the ability to sustain or further improve these important clinical outcomes. (Surg Obes Relat Dis 2010;6:361–366.) © 2010 American Society for Metabolic and Bariatric Surgery. All rights reserved.

Keywords:

Obesity; Bariatric surgery; Gastric bypass; Physical activity; Physical function

Obesity is a significant public health problem, with the prevalence of severe obesity reaching epidemic proportions [1]. Obesity is associated with impairments of the individual’s physical and psychological health and has been linked to physical disability and decreased health-related quality of

Reprints not available from the authors.

life (HRQOL). These, in turn, have significant effects on health outcomes [2,3]. Weight loss has been shown to decrease the risk of many of these co-morbid conditions [4]. Behavioral interventions, including modifications to both diet and exercise, have traditionally been used to address obesity and have been shown to reduce the body weight by approximately 10% in the short term [5]. Alternatively, bariatric surgery has been

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shown to reduce the body weight ⱕ38% at 1 year and has been shown to result in improved long-term resolution of co-morbidities [6]. Similar to behavioral approaches, weight loss resulting from bariatric surgery has also been associated with a reduction in depressive symptoms and improved self-esteem [7]. Physical activity is an important contributor to the longterm maintenance of weight loss [8]. Evidence has shown that individuals increase their physical activity participation after bariatric surgery, contributing to the improved longterm surgical outcomes [9]. However, limited studies have investigated the effect of bariatric surgery on objective measures of physical function (i.e., what the patient is physically capable of doing)—specifically whether an increase in physical function is associated with an increase in physical activity (i.e., what the patient does) after surgery. Thus, we investigated the changes in physical activity, physical function, HRQOL, and psychosocial correlates of physical activity before and after bariatric surgery. Methods Subjects The subjects were 20 consecutive participants who were scheduled to undergo laparoscopic gastric bypass surgery (GBS) at a tertiary care center. Patients who were unable to ambulate independently or who were not cleared by their physician for participation were excluded. All participants provided written informed consent before undergoing the series of assessments described in this report. The assessments were completed at baseline (3– 4 weeks preoperatively) and at 3-months postoperatively. Physical activity was encouraged postoperatively, but no formal exercise guidelines were given. The institutional review board approved this study. Assessment measures The assessments included physical activity, physical function, HRQOL, pain, and psychosocial factors that might influence physical activity. The specific assessment techniques are described in detail. Physical activity was assessed using the 7-day Physical Activity Recall questionnaire (7-d PAR) and a pedometer. On the 7-d PAR, the patients self-report moderate, hard, and very hard periods of physical activity performed during the 7-day period. The total duration of physical activity classified as “at least moderate intensity” was computed and used for analysis. This self-administered questionnaire has been shown to provide valid and reliable estimates of habitual physical activity [10]. A pedometer (Digi-walker SW-200) was used to obtain an objective measure of ambulatory physical activity. The subjects were instructed to wear the pedometer daily for 1 week before their scheduled GBS and for 1 week before

their scheduled 3-month follow-up assessment. They were provided a diary to record their daily steps. The data are presented as the average steps taken daily. Physical function was assessed using both performancebased and self-reported measures. The 6-minute walk test (6MWT) measures the distance walked in 6 minutes on level ground, stopping to rest as needed. The 6MWT has established test-retest reliability and concurrent and group validity [11]. The subjects were told that the purpose of this test was to determine the distance they could walk in 6 minutes. They were instructed to “walk at their own pace in order to cover as much ground as possible.” The Short Physical Performance Battery (SPPB) is a battery of tests that has been used to assess lower extremity function in the older population [12]. This battery uses a scale from 0 (poor) to 12 (excellent) to summarize the performance of 3 tasks (a 4-m walk, standing balance, and rising from a chair). The SPPB has been shown to be valid, reliable, and sensitive to change [13]. For the 4-m walk, the subject walks a distance of 4 m at their normal pace to determine gait speed, computed as the time to complete the 4-m walk. For the standing balance test, the subjects placed their feet in a side-by-side position, followed by a semitandem position (heel of 1 foot along the side of the big toe of the opposite foot) and a tandem position (heel of one foot directly in front of the other). The subjects were required to hold the side-by-side position for 10 seconds before advancing to the semitandem position and to hold the semitandem position for 10 seconds before advancing to the tandem position. For the chair rise test, the subject was seated in a chair that was 18-in. tall, with their arms crossed, and how quickly they could stand 5 times from sitting in the chair was assessed [13]. Finally, self-reported physical function was measured using the physical function subscale of the Medical Outcomes Short Form-36 (SF-36). This measure assesses the limitations in activities of daily living such as bathing, dressing, and mobility. This domain is scored from 0 (lowest level of functioning) to 100 (greatest level of functioning). HRQOL was assessed using the SF-36. The SF-36 is a well-established, psychometrically sound, health status questionnaire [14]. The SF-36 measures limitations in 8 functional areas (physical activities, social functioning, physical factors, emotional factors, bodily pain, general mental health, vitality, and general health). Pain was assessed using the Numeric Pain Rating Scale. This instrument measures pain intensity in weight-bearing joints that limits walking ability. Scoring is on an 11-point numeric pain rating scale and has been shown be reliable and valid as a measure of pain intensity [15]. To measure the psychosocial correlates of physical ac-

D. A. Josbeno et al. / Surgery for Obesity and Related Diseases 6 (2010) 361–366 Table 1 Demographic information (n ⫽ 20) Variable Gender Female Male Race/Ethnicity Black Hispanic White Education High school graduate Vocational training Some college College/university degree Graduate or professional education Employment status Currently working Professional Clerical Crafts, trade, factory worker, labor Other

% (n) 90.0 (18) 10.0 (2) 10.0 (2) 5.0 (1) 85.0 (17) 15.0 (3) 25.0 (5) 35.0 (7) 20.0 (4) 5.0 (1) 85.0 (17) 40.0 (8) 25.0 (5) 10.0 (2) 10.0 (2)

tivity, we used the Physical Activity Self-Efficacy questionnaire. This questionnaire, developed by Marcus et al. [16] was used to assess physical activity self-efficacy. The internal consistency of this 5-item measure is .76, with a test-retest reliability of .90. We also used the Physical Activity Barriers and Outcome Expectations questionnaire. This questionnaire, developed by Steinhardt and Dishman [17], is used to assess outcome expectations and barriers to physical activity. Internal consistency coefficients for this measure range from .47 to .78, with test-retest stability correlations of .66 –.89. Statistical analysis A comparison of the baseline and 3-month data was performed using dependent t tests to determine changes in the variables from baseline (preoperatively) to 3 months after GBS. Correlation coefficients were computed to assess the relationship between the activity level and physical function. In addition, correlations were computed to assess the relationship between physical activity with the measures of HRQOL and psychosocial outcomes. Data were assessed for normality, and when not normally distributed, nonparametric statistical tests were used. All analyses were performed using Statistical Package for Social Sciences software, version 15.0 for Windows (SPSS, Chicago, IL), with statistical significance defined as P ⱕ.05. Results A total of 20 patients who had undergone laparoscopic GBS were included in this study. Their mean age was 41.6 ⫾ 9.8 years; additional demographic data are listed in Table 1. Of the 20 patients, 2 (10%) were lost to follow-up.

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At 3 months postoperatively, the average weight loss was 24.4 ⫾ 5.6 kg, decreasing the body mass index from 46.9 ⫾ 6.3 kg/m2 to 37.4 ⫾ 5.7 kg/m2 (P ⫽ .00). This resulted in a percentage of excess weight loss of 39.5% ⫾ 7.1%. The physical activity and physical function data are listed in Table 2. A nonsignificant increase of 40.6 ⫾ 299.67 min/wk of moderate-to-vigorous intensity physical activity, measured using the 7-d PAR, was seen from before to after GBS (P ⫽ .43). However, the self-reported pedometer readings (steps/d) increased significantly by 2750 ⫾ 2016.06 steps/d (P ⫽ 0.003). Additionally, significant improvements in the performance-based and self-report physical function measures were observed. The 6MWT increased significantly by 55 ⫾ 64.04 m (P ⫽ 0.003), the SPPB increased significantly by .5 ⫾ 1.04 (P ⫽ .04), and the physical function subscale score of the SF-36 increased from 65.0 ⫾ 18.5 to 84.1 ⫾ 19.9 (P ⱕ.000). The psychosocial and HRQOL outcomes are also presented in Table 2. An increase was noted in the Physical Activity Self-Efficacy score from 2.6 ⫾ .97 to 3.0 ⫾ .85 (P ⫽ .06). No significant changes were observed for the Physical Activity Barriers and Outcome Expectations questionnaire. The HRQOL increased significantly from 38.2 ⫾ 23.58 to 89.7 ⫾ 15.5 (P ⫽ .000). Additionally, pain ratings using the Numeric Pain Rating Scale improved significantly for low back (3.5 ⫾ 1.8 to 1.7 ⫾ 2.63), knee (2.4 ⫾ 2.51 to 1.0 ⫾ 1.43), and foot/ankle (2.3 ⫾ 2.8 to .9 ⫾ 2.05) pain. Significant, but moderate, correlations were found between physical activity and physical function as measured by the SPPB before GBS and between physical activity and both the 6MWT and the SPPB after GBS. HRQOL and pain were not significantly correlated with physical activity before or after GBS. The psychosocial factors did not correlate with physical activity (Table 3). Discussion This study was undertaken to address the paucity of information related to physical activity and physical function changes associated with GBS. Boan et al. [18] examined the changes in physical activity and self-reported physical function at 6 months after GBS. Their results showed a significant improvement in physical activity, a decrease in the reported amount of time watching television after GBS, and improvement in self-reported physical function [18]. Maniscalco et al. [19] also reported graded improvement in walking ability, with a reduction in body mass index at 1 year after adjustable gastric banding surgery. The results of the present study are consistent with these improvements in physical function after weight loss surgery, with significant improvements in the 6MWT (393 ⫾ 62.08 m to 446 ⫾ 41.39 m) and the physical function subscale of the SF-36 scores (65 ⫾ 18.5 to 84.1 ⫾ 19.9). Although our subjects did improve in their walking distance, they were functioning at a level that was established

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Table 2 Change in variables from before to 3 months after surgery Variable Physical activity* (n ⫽ 18) 7-d PAR (min/wk) Pedometer (steps/d) (n ⫽ 11) Physical function* (n ⫽ 17) 6MWT (m) SPPB (n ⫽ 18) SF-36PF score Psychosocial correlates of PA (n ⫽ 17) PASE* PA barriers† Time Effort Obstacles Total barriers PA outcome expectations* Psychological Image Health Total benefits HRQOL (n ⫽ 17) SF-36 total score* Pain† (n ⫽ 17) Low back Hip Knee Foot/ankle

Before surgery

3-mo After surgery

Difference

P value

191.1 ⫾ 228.23 4621 ⫾ 3701.18

231.7 ⫾ 239.04 7370 ⫾ 4240.14

40.6 ⫾ 299.67 2750 ⫾ 2016.06

.43 .003

393 ⫾ 62.08 11.2 ⫾ 1.22 65 ⫾ 18.50

446 ⫾ 41.39 11.7 ⫾ 0.57 84.1 ⫾ 19.90

55 ⫾ 64.04 .50 ⫾ 1.04 19.1 ⫾ 10.93

.003 .04 .000

2.6 ⫾ 0.97

3.0 ⫾ 0.85

.36 ⫾ 0.91

.06

2.8 ⫾ 0.93 2.7 ⫾ 0.74 2.5 ⫾ 0.80 2.7 ⫾ 0.48

2.9 ⫾ 0.25 2.6 ⫾ 0.74 2.3 ⫾ 0.68 2.6 ⫾ 0.50

.08 ⫾ 0.78 ⫺.1 ⫾ 0.97 ⫺.24 ⫾ 1.02 ⫺.11 ⫾ 0.72

.68 .68 .95 .57

3.7 ⫾ 0.82 4.6 ⫾ 0.59 4.5 ⫾ 0.55 4.2 ⫾ 0.57

3.7 ⫾ 0.70 4.4 ⫾ 0.64 4.6 ⫾ 0.54 4.2 ⫾ 0.55

.06 ⫾ 0.68 ⫺.16 ⫾ 0.48 .02 ⫾ 0.64 ⫺.02 ⫾ 0.48

.79 .19 .83 .84

38.2 ⫾ 23.58

89.7 ⫾ 15.50

51.47 ⫾ 22.48

.000

3.5 ⫾ 1.80 1.3 ⫾ 2.17 2.4 ⫾ 2.51 2.3 ⫾ 2.80

1.7 ⫾ 2.63 .31 ⫾ 0.81 1.0 ⫾ 1.43 .90 ⫾ 2.05

⫺1.9 ⫾ 2.81 ⫺.96 ⫾ 2.21 ⫺1.4 ⫾ 1.70 ⫺1.5 ⫾ 2.02

.01 .09 .004 .008

7-d PAR ⫽ 7-day Physical Activity Recall questionnaire; 6MWT ⫽ 6-minute walking test; SPPB ⫽ Short Physical Performance Battery; SF-36PF ⫽ physical function subscale of the Medical Outcomes Short Form-36; PA ⫽ physical activity; PASE ⫽ Physical Activity Self-Efficacy; HRQOL ⫽ health-related quality of life. * Greater score is desirable directional outcome. † Lower score is desirable directional outcome.

for a much older population. Their 6MWT distance at 3 months after GBS was comparable to that observed for active community-dwelling older adults [20]. Several studies have shown that obese individuals demonstrate gait abnormalities that can contribute to decreased walking capacity [21,22]. Moreover, for a given velocity of walking, the metabolic cost per kilogram of body mass is greater for obese individuals than for those of normal weight [22,23]. Hulens et al. [24] reported that obese individuals walked slower than lean individuals (body mass index 22.1 ⫾ 2.1 kg/m2) and reported greater levels of perceived physical exertion and musculoskeletal pain during a 6MWT. These factors could have contributed to the slower gait speed and distance observed after losing significant weight from GBS. The observed improvements in physical function were accompanied by a nonsignificant increase in moderate-tovigorous physical activity of 40.6 min/wk as measured by self-report. Moreover, a subsample of subjects reported an increase in daily steps of 2750 ⫾ 2016 steps/d (n ⫽ 11). These findings might have been influenced by the limitations in the methods used to assess physical activity. For example, the subjects reported all household, occupational, and leisure-time physical activity on the 7-d PAR, which could have contributed to the relatively high levels of phys-

ical activity at baseline (191.1 ⫾ 228.23 min/wk) and after GBS (231.7 ⫾ 239.04 min/wk). The pedometer might have also inaccurately measured the magnitude of physical activity before and after GBS. For example, the pedometer might not have accurately assessed activities other than level walking, the positioning of the pedometer could have affected the accuracy of the measurement, and subjects were required to accurately self-report their daily steps to the investigators [25]. It has also been shown that obese individuals inaccurately report their physical activity, which could have contributed to the patterns observed in this study [26]. Therefore, the use of objective monitoring of physical activity should be considered for future studies of obese individuals before and after bariatric surgery. We also recognized that selection bias is another limitation and consequently decreases the ability to generalize our results. The finding that weight loss induced by bariatric surgery correlates with improved HRQOL is consistent with the findings of previously reported studies [27]. Improvements in physical performance measures (6MWT), physical activity (pedometer step count), and pain paralleled this improvement in HRQOL. Improved HRQOL can be influenced by a reduction in self-reported pain. This decrease in pain is consistent with studies reporting decreased musculoskeletal

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Table 3 Correlation between physical activity and physical function, psychosocial parameters, health-related quality of life, and pain Outcome measure

Physical function 6MWT Patients (n)

Physical activity Before GBS

After GBS

Change in physical activity with change in outcome measures*

19

17

17

.39 (P ⫽ .10)† SPPB Patients (n)

20

.60 (P ⫽ .01) 18

18

.84 (P ⫽ .000)† SF-36PF Patients (n)

20

.55 (P ⫽ .02) 17

20

PA barriers Patients (n) Time Effort Obstacles Total barriers PA outcome expectations Patients (n) Psychological Image Health Total benefits HRQOL Patients (n) SF-36 total score Pain Patients (n) Low back Hip Knee Foot/ankle

.40 (P ⫽ .11)

17 .17 (P ⫽ .46)

20

.48 (P ⫽ .05) 17

.41 (P ⫽ .07) Psychosocial parameters PASE Patients (n)

.53 (P ⫽ .03)

.40 (P ⫽ .11)

17 .39 (P ⫽ .13)

.17 (P ⫽ .52)†

17 ⫺.01 (P ⫽ .99) ⫺.2 (P ⫽ .45) ⫺.27 (P ⫽ .29) ⫺.29 (P ⫽ .28)

16

.29 (P ⫽ .22) ⫺.03 (P ⫽ .92) .45 (P ⫽ .05) .23 (P ⫽ .33) 20 ⫺.31 (P ⫽ .19) ⫺.06 (P ⫽ .81) ⫺.10 (P ⫽ .67) ⫺.23 (P ⫽ .33)

17 ⫺.144 (P ⫽ .58) .02 (P ⫽ .94) ⫺.08 (P ⫽ .78) ⫺.16 (P ⫽ .55)

16 ⫺.43 (P ⫽ .09)† .12 (P ⫽ .65)† .03 (P ⫽ .91)† ⫺.21 (P ⫽ .43)†

20 ⫺.17 (P ⫽ .46)

17

17

20 ⫺.02 (P ⫽ .94) ⫺.02 (P ⫽ .92) ⫺.11 (P ⫽ .64) ⫺.04 (P ⫽ .87)

17

17

.07 (P ⫽ .79) .11 (P ⫽ .68) ⫺.36 (P ⫽ .15) ⫺.14 (P ⫽ .59)

.21 (P ⫽ .41)† ⫺.09 (P ⫽ .75)† .42 (P ⫽ .09) ⫺.01 (P ⫽ .98)

.47 (P ⫽ .06)

.50 (P ⫽ .05)† ⫺.09 (P ⫽ .73)† ⫺.15 (P ⫽ .58)† ⫺.002 (P ⫽ .99)†

.4 (P ⫽ .11)

GBS ⫽ gastric bypass surgery; other abbreviations as in Table 2. Data presented as correlation coefficient (P value). * Change in measures calculated as 3-mo post-GBS score ⫺ pre-GBS score. † Pearson (all others Spearman’s).

pain in response to weight loss induced by bariatric surgery [28,29]. An examination of the data showed that the subjects reported high scores on the Physical Activity Barriers and Outcome Expectations questionnaire. This finding is consistent with the results reported by Gallagher et al. [30]. However, the barriers to physical activity were unchanged after surgery compared with before surgery, which might have contributed to the limited improvement in physical activity observed. This limitation might have been a result of a lack of focus in addressing the barriers to physical activity in this population. In response to a behavioral intervention, Gallagher et al. [30] reported a significant reduction in barriers to physical activity, and the barriers were inversely associated with physical activity after a 6-month

behavioral weight loss intervention. Thus, interventions that focus on the barriers to physical activity might need to be implemented to address these factors in obese individuals. This could lead to improved physical activity after bariatric surgery. In turn, this could affect long-term weight loss maintenance and have an independent effect on chronic disease risk factors. Conclusion In addition to the previously reported improvements in chronic disease co-morbidities [6], weight loss resulting from bariatric surgery can improve physical function and HRQOL. In a sample of patients evaluated 3 months after GBS, significant improvements in physical function and

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HRQOL, a reduction in pain, and a trend toward increased physical activity were found. However, the barriers to physical activity remained unchanged from before to after GBS, perhaps limiting the improvements in physical activity. Thus, interventions that specifically target the barriers to physical activity might be beneficial to maximize weight loss maintenance and minimize chronic disease risk factors. The results of this study have provided important information related to the benefits of bariatric surgery and should contribute to the ongoing development of effective postoperative exercise guidelines that will maximize surgical success. Acknowledgments The authors wish to acknowledge Bret H. Goodpaster, Ph.D., for his assistance with this study. Disclosures The authors claim no commercial associations that might be a conflict of interest in relation to this article. References [1] Sturm R. Increases in clinically severe obesity in the United States, 1986 –2000. Arch Intern Med 2003;163:2146 – 8. [2] McTigue K, Larson JC, Valoski A, et al. Mortality and cardiac and vascular outcomes in extremely obese women. JAMA 2006;296: 79 – 86. [3] Kolotkin RL, Crosby RD, Pendleton R, Strong M, Gress RE, Adams T. Health-related quality of life in patients seeking gastric bypass surgery vs non-treatment-seeking controls. Obes Surg 2003;13: 371–7. [4] Goodpaster BH, Kelley DE, Wing RR, Meier A, Thaete FL. Effects of weight loss on regional fat distribution and insulin sensitivity in obesity. Diabetes 1999;48:839 – 47. [5] Wing RR, Hill JO. Successful weight loss maintenance. Ann Rev Nutr 2001;21:323– 41. [6] Sjöström L, Lindroos AK, Peltonen M, et al., for the Swedish Obese Subjects Study Scientific Group. Lifestyle, diabetes, and cardiovascular risk factors 10 years after bariatric surgery. N Engl J Med 2004;351:2683–2693. [7] Burgmer R, Petersen I, Burgmer M, de Zwaan M, Wolf AM, Herpertz S. Psychological outcome two years after restrictive bariatric surgery. Obes Surg 2007;17:785–91. [8] Jakicic JM, Clark K, Coleman E, et al., for the American College of Sports Medicine. American College of Sports Medicine position stand: appropriate intervention strategies for weight loss and prevention of weight regain for adults. Med Sci Sports Exerc 2001;33: 2145–56. [9] Bond DS, Evans RK, Wolfe LG, et al. Impact of self-reported physical activity participation on proportion of excess weight loss and BMI among gastric bypass surgery patients. Am Surg 2004;70: 811– 4.

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