Increased exercise capacity after surgically induced weight loss in morbid obesity

Respiratory Consequences of Mild-to-Moderate Obesity: Impact on Exercise Performance in Health and in Chronic Obstructive Pulmonary Disease

In many parts of the world, the prevalence of obesity is increasing at an alarming rate. The association between obesity, multiple comorbidities, and increased mortality is now firmly established in many epidemiological studies. However, the link between obesity and exercise intolerance is less well studied and is the focus of this paper. Although exercise limitation is likely to be multifactorial in obesity, it is widely believed that the respiratory mechanical constraints and the attendant dyspnea are important contributors. In this paper, we examined the evidence that critical ventilatory constraint is a proximate source of exercise limitation in individuals with mild-to-moderate obesity. We first reviewed existing information on exercise performance, including ventilatory and perceptual response patterns, in obese individuals who are otherwise healthy. We then considered the impact of obesity in patients with preexisting respiratory mechanical abnormalities due to chronic obstructive pulmonary disease (COPD), with particular reference to the effect on dyspnea and exercise performance. Our main conclusion, based on the existing and rather sparse literature on the subject, is that abnormalities of dynamic respiratory mechanics are not likely to be the dominant source of dyspnea and exercise intolerance in otherwise healthy individuals or in patients with COPD with mild-to-moderate obesity.

Six-minute walk test improved forearm skin blood flow in Tunisian obese women

The purpose of this study was to investigate whether 6-min walk test (6MWT) would improve the forearm skin blood flow (FSBF) response to acetylcholine (ACh), an endothelium-dependent vasodilator, in Tunisian women over a wide range of BMI. The FSBF was measured noninvasively using a laser Doppler flowmeter in response to local infusion of a cumulative dose of ACh, before and after the 6MWT for 102 healthy women; the results were expressed as percentage of baseline. The 6MWT was monitored and recorded. The mean response of FSBF to ACh was significantly greater before as well as after the 6MWT in lean (1,235 ± 123% vs. 1,644 ± 140%) than in overweight (630 ± 62% vs. 1,080 ± 66%) and obese subjects (402 ± 38% vs. 795 ± 40%) (P < 0.0001). Our regression analysis also revealed that the maximal FSBF response to ACh (i.e., its efficacy) was inversely correlated with BMI both before as well as after the 6MWT (r = -0.828, P < 0.0001; r = -0.859, P < 0.0001, respectively), and the efficacies of ACh in the three groups were all significantly elevated following the 6MWT (P < 0.0001). As indicated by ANOVA test, the 6MWT improved the FSBF responses of the lean, overweight, and obese subjects, by 33, 71, and 98%, respectively. We confirm that obesity induced a reduction of skin vasodilatory reserve and altered both endothelial-dependent relaxation and wall compliance. However, our new data clearly demonstrated that the 6MWT not only improved significantly the FSBF responses in the three groups of women, but the obese patients appeared to benefit more from the 6MWT than the overweight and the lean subjects.

Physical activity and weight loss following bariatric surgery

Physical activity is a cornerstone in the medical management of obesity and could be important for weight loss following bariatric surgery. This review aims to describe the evolution of physical activity following massive weight loss induced by bariatric surgery, and to identify the relationship between physical activity and amount of weight loss. A literature search identified 20 publications (19 studies) reporting physical activity data in relation to bariatric surgery. All studies were observational. Self-assessment of physical activity was used in all the studies. Objective measures (pedometry) were used in two studies. The time frame for physical activity assessment varied: before surgery in two publications, after surgery in nine, and longitudinal pre- to post-operative evolution in nine. The latter nine publications found an increase in physical activity after bariatric surgery. In 10/13 studies where it was described, there was a positive relationship between physical activity level and amount of weight loss. In conclusion, observational evidence of self-reported physical activity suggests that physical activity increases after bariatric surgery and that physical activity is associated with surgically induced weight loss. However, these findings warrant further evaluation using objective measures of physical activity and testing in controlled trials.

Endocrine and nutritional management of the post-bariatric surgery patient: an Endocrine Society Clinical Practice Guideline

OBJECTIVE

We sought to provide guidelines for the nutritional and endocrine management of adults after bariatric surgery, including those with diabetes mellitus. The focus is on the immediate postoperative period and long-term management to prevent complications, weight regain, and progression of obesity-associated comorbidities. The treatment of specific disorders is only summarized.

PARTICIPANTS

The Task Force was composed of a chair, five additional experts, a methodologist, and a medical writer. It received no corporate funding or remuneration.

CONCLUSIONS

Bariatric surgery is not a guarantee of successful weight loss and maintenance. Increasingly, patients regain weight, especially those undergoing restrictive surgeries such as laparoscopic banding rather than malabsorptive surgeries such as Roux-en-Y bypass. Active nutritional patient education and clinical management to prevent and detect nutritional deficiencies are recommended for all patients undergoing bariatric surgery. Management of potential nutritional deficiencies is particularly important for patients undergoing malabsorptive procedures, and strategies should be employed to compensate for food intolerance in patients who have had a malabsorptive procedure to reduce the risk for clinically important nutritional deficiencies. To enhance the transition to life after bariatric surgery and to prevent weight regain and nutritional complications, all patients should receive care from a multidisciplinary team including an experienced primary care physician, endocrinologist, or gastroenterologist and consider enrolling postoperatively in a comprehensive program for nutrition and lifestyle management. Future research should address the effectiveness of intensive postoperative nutritional and endocrine care in reducing morbidity and mortality from obesity-associated chronic diseases.

Respiratory function and the obesity paradox

PURPOSE OF REVIEW

Obese individuals have impaired respiratory function relative to their normal-weight counterparts. Despite these negative effects, obesity is paradoxically associated with better survival in individuals with chronic obstructive pulmonary disease (COPD). The purpose of this review is to describe this 'obesity paradox', to discuss the effects of obesity on respiratory function, and to speculate as to whether obesity-related alterations in respiratory mechanics can influence the natural history of COPD.

RECENT FINDINGS

Given the known negative effects of obesity on respiratory physiology, it is reasonable to predict that obese COPD patients would be more likely to experience greater dyspnea and exercise intolerance relative to COPD patients of normal weight. However, recent evidence suggests that obese COPD patients have similar or better dyspnea scores during exercise and do not have diminished exercise capacity. These observations may be attributable to the fact that obese COPD patients have reduced operating lung volumes and higher inspiratory capacity to total lung capacity ratios than their lean COPD counterparts.

SUMMARY

Obese patients with COPD do not appear to be at a disadvantage during exercise relative to lean COPD patients. Obesity may be associated with improved survival in COPD but specific mechanisms for this paradox remain to be elucidated.

The Role of Physical Activity Participation in Weight Loss Outcomes Following Weight Loss Surgery

Weight loss surgery (WLS) is an effective intervention for the reduction of body mass and the resolution of obesity-related comorbidities. Excess weight loss following WLS has been reported in the range of 40% to 78% depending on the surgery type and the follow-up time period. Initial weight loss outcomes and weight loss maintenance have been shown to depend on several factors, including the type of surgical procedure, preexisting comorbidities, and compliance with postoperative medical, nutritional, and behavioral recommendations. One factor that has received limited attention in the scientific literature is the role of physical activity in initial weight loss and maintenance following WLS. Physical activity participation of sufficient frequency, intensity, and duration during both the pre- and postoperative time periods has the potential to reduce surgical complications, enhance weight loss outcomes, and improve physical fitness and overall health following WLS. In addition, physical activity has the potential to improve the quality of postoperative weight loss by enhancing fat mass loss while preserving fat-free mass, thereby minimizing the impact of massive weight loss on metabolic rate. In light of these potential benefits, appropriate interventions should be employed to promote physical activity participation of appropriate frequency, intensity, and duration both before and after WLS.

Physical fitness in morbidly obese patients: effect of gastric bypass surgery and exercise training

BACKGROUND

There is a growing consensus that bariatric surgery is currently the most efficacious and long-term treatment for clinically severe obesity. However, it remains to be determined whether poor physical fitness, an important characteristic of these patients, improves as well. The purpose of this pilot study is to investigate the effect of gastric bypass surgery on physical fitness and to determine if an exercise program in the first 4 months is beneficial.

METHODS

Fifteen morbidly obese patients (BMI 43.0 kg/m(2)) were tested before and 4 months after gastric bypass surgery. Eight of them followed a combined endurance and strength training program. Before and after 4 months the operation, anthropometrical characteristics were measured, and an extensive assessment of physical fitness (strength, aerobic, and functional capacity) was performed.

RESULTS

Large-scale weight loss through gastric bypass surgery results in a decrease in dynamic and static muscle strength and no improvement of aerobic capacity. In contrast, an intensive exercise program could prevent the decrease and even induced an increase in strength of most muscle groups. Together with an improvement in aerobic capacity, functional capacity increased significantly. Both groups evolved equally with regard to body composition (decrease in fat mass and fat-free mass).

CONCLUSIONS

An exercise training program in the first 4 months after bariatric surgery is effective and should be promoted, considering the fact that physical fitness does not improve by weight loss only.

Do mechanical gait parameters explain the higher metabolic cost of walking in obese adolescents?

Net metabolic cost of walking normalized by body mass ( CW·BM−1; in J·kg−1·m−1) is greater in obese than in normal-weight individuals, and biomechanical differences could be responsible for this greater net metabolic cost. We hypothesized that, in obese individuals, greater mediolateral body center of mass (COM) displacement and lower recovery of mechanical energy could induce an increase in the external mechanical work required to lift and accelerate the COM and thus in net CW·BM−1. Body composition and standing metabolic rate were measured in 23 obese and 10 normal-weight adolescents. Metabolic and mechanical energy costs were assessed while walking along an outdoor track at four speeds (0.75–1.50 m/s). Three-dimensional COM accelerations were measured by means of a tri-axial accelerometer and gyroscope and integrated twice to obtain COM velocities, displacements, and fluctuations in potential and kinetic energies. Last, external mechanical work (J·kg−1·m−1), mediolateral COM displacement, and the mechanical energy recovery of the inverted pendulum were calculated. Net CW·BM−1 was 25% higher in obese than in normal-weight subjects on average across speeds, and net CW·BM−67 (J·kg−0.67·m−1) was significantly related to percent body fat ( r2 = 0.46). However, recovery of mechanical energy and the external work performed (J·kg−1·m−1) were similar in the two groups. The mediolateral displacement was greater in obese subjects and significantly related to percent body fat ( r2 = 0.64). The mediolateral COM displacement, likely due to greater step width, was significantly related to net CW·BM−67 ( r2 = 0.49). In conclusion, we speculate that the greater net CW·BM−67 in obese subjects may be partially explained by the greater step-to-step transition costs associated with wide gait during walking.

Six-minute walk test: functional capacity of severely obese before and after bariatric surgery

BACKGROUND

The 6-minute walk test (6MWT) is a well-known instrument for assessing the functional capacity of a variety of groups, including the obese. It is a simple, low-cost and easily applied method to objectively assess the level of exercise capacity. The aim of the present study was to study the functional capacity of a severely obese population before and after bariatric surgery.

METHODS

A total of 51 patients were studied. Of the 51 patients, 86.2% were women, and the mean age was 40.9 + or - 9.2 years. All 51 patients were evaluated preoperatively and 49 were evaluated 7-12 months postoperatively. The initial body mass index was 51.1 + or - 9.2 kg/m(2), and the final body mass index was 28.2 + or - 8.1 kg/m(2). All patients underwent Roux-en-Y gastric bypass. The 6MWT was performed in a hospital corridor, with patients attempting to cover as much distance as they could, walking back and forth for as long as possible within 6 minutes at their regular pace. The total distance, Borg Scale of perceived exhaustion, modified Borg dyspnea scale for shortness of breath, and physical complaints at the end of the test were recorded. In addition, the heart rate and respiratory frequency were assessed before and after the test.

RESULTS

The tolerance was good, and no injuries occurred at either evaluation. The patients' mean distance for the 6MWT was 381.9 + or - 49.3 m before surgery and 467.8 + or - 40.3 m after surgery (p <.0001). Similar results were observed for the other parameters assessed.

CONCLUSION

The 6MWT provided useful information about the functional status of the obese patients undergoing bariatric surgery. A simple, safe, and powerful method to assess functional capacity of severely obese patients, the 6MWT is an objective test that might replace the conventional treadmill test for these types of patients.

Best practice updates for multidisciplinary care in weight loss surgery

The objective of this study is to update evidence-based best practice guidelines for multidisciplinary care of weight loss surgery (WLS) patients. We performed systematic search of English-language literature on WLS, patient selection, and medical, multidisciplinary, and nutritional care published between April 2004 and May 2007 in MEDLINE and the Cochrane Library. Key words were used to narrow the search for a selective review of abstracts, retrieval of full articles, and grading of evidence according to systems used in established evidence-based models. A total of 150 papers were retrieved from the literature search and 112 were reviewed in detail. We made evidence-based best practice recommendations from the most recent literature on multidisciplinary care of WLS patients. New recommendations were developed in the areas of patient selection, medical evaluation, and treatment. Regular updates of evidence-based recommendations for best practices in multidisciplinary care are required to address changes in patient demographics and levels of obesity. Key factors in patient safety include comprehensive preoperative medical evaluation, patient education, appropriate perioperative care, and long-term follow-up.

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery medical guidelines for clinical practice for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery Medical Guidelines for Clinical Practice are systematically developed statements to assist health-care professionals in medical decision making for specific clinical conditions. Most of the content herein is based on literature reviews. In areas of uncertainty, professional judgment was applied. These guidelines are a working document that reflects the state of the field at the time of publication. Because rapid changes in this area are expected, periodic revisions are inevitable. We encourage medical professionals to use this information in conjunction with their best clinical judgment. The presented recommendations may not be appropriate in all situations. Any decision by practitioners to apply these guidelines must be made in light of local resources and individual patient circumstances. The American Society for Parenteral & Enteral Nutrition fully endorses sections of these guidelines that address the metabolic and nutritional management of the bariatric surgical patient.

Heart rate behavior during an exercise stress test in obese patients

BACKGROUND AND AIMS

Heart rate (HR) response to exercise has not been fully described in the obese. We wanted to study the differences between obese and non-obese patients in HR behavior during an exercise stress test and to determine whether these differences influence exercise capacity.

METHODS AND RESULTS

We studied 554 patients (318 females) who underwent a treadmill exercise test. All subjects were in sinus rhythm. Patients with ischemic heart disease, with reduced ejection fraction and patients taking drugs that interfere with HR were excluded. The population included 231 patients with BMI<30 kg/m(2) (group 1), 212 patients who were unfit and obese (group 2) and 111 patients who were trained obese (group 3). Resting HR was similar in the various groups. Peak HR, HR recovery and chronotropic index were lower in obese subjects, regardless of their fitness level. Multivariate analysis showed that HR related variables were associated with age, BMI, height, hypertension and various pharmacologic treatments, while exercise capacity was strongly dependent on HR behavior, as well as on sex, age, BMI and diabetes.

CONCLUSION

Obese subjects have a marked impairment of HR behavior during exercise and in the recovery period, and the blunted increase in HR is the most important factor that influences exercise capacity.

Bariatric surgery reduces cancer risk in morbidly obese patients

BACKGROUND

To assess the effect of bariatric surgery on the cancer risk of patients with morbid obesity because evidence is mounting of an association between obesity and cancer.

METHODS

We performed an observational 2-cohort study. The treatment cohort (n = 1035) included patients who had undergone bariatric surgery from 1986 to 2002. The control group (n = 5746) included age- and gender-matched morbidly obese patients who had not undergone weight-reduction surgery and who were identified from a single-payor administrative database. The subjects with physician or hospital visits for a cancer-related diagnosis or treatment within the 6 months previous to the beginning of the study were excluded. The cohorts were followed up for a maximum of 5 years from study inception.

RESULTS

Bariatric surgery resulted in a significant reduction in the mean percentage of excess weight loss (67.1%, P <.001). The surgery patients had significantly fewer physician/hospital visits for all cancer diagnoses (n = 21, 2.0%) compared with the controls (n = 487, 8.45%; relative risk .22, 95% confidence interval .143-.347; P = .001). The physician/hospital visits for common cancers such as breast cancer were significantly reduced in the surgery group (P = .001). For all other cancers, the physician/hospital visits showed a trend toward being lower in the surgery group. Because of the low frequencies, statistical significance could not be demonstrated for individual cancer diagnoses.

CONCLUSION

The data suggest that bariatric surgery improves the cancer outcomes in some morbidly obese patients.

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery Medical Guidelines for Clinical Practice for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery Medical Guidelines for Clinical Practice are systematically developed statements to assist healthcare professionals in medical decision making for specific clinical conditions. Most of the content herein is based on literature reviews. In areas of uncertainty, professional judgment was applied. These guidelines are a working document that reflects the state of the field at the time of publication. Because rapid changes in this area are expected, periodic revisions are inevitable. We encourage medical professionals to use this information in conjunction with their best clinical judgment. The presented recommendations may not be appropriate in all situations. Any decision by practitioners to apply these guidelines must be made in light of local resources and individual patient circumstances. The American Society for Parenteral & Enteral Nutrition fully endorses sections of these guidelines that address the metabolic and nutritional management of the bariatric surgical patient.

Impact of obesity and bariatric surgery on cardiovascular disease

Morbid obesity is a growing public health concern with multiple associated cardiovascular comorbidities. Bariatric surgery has emerged as a safe and effective treatment for morbidly obese patients at risk for, or already suffering from, cardiovascular disease. Weight loss induced by the surgery has been shown to improve cardiovascular risk factors, cardiac structure and function, and the clinical course of established cardiovascular disease. The role of adipocyte-derived cytokines in mediating cardiovascular pathophysiology in obesity-and its modulation after weight loss-is under active investigation.

The Effects of Obesity on Functional Work Capacity and Quality of Life in Phase II Cardiac Rehabilitation

Many patients referred to cardiac rehabilitation (CR) programs are obese. It is unknown, however, whether obese patients derive reduced benefit from CR. A total of 388 CR patients were categorized into normal-weight, overweight, class I obese, and class II/III obese groups. Functional work capacity and quality of life were examined at baseline and after 12-week completion of the CR program. After adjusting for demographic and medical conditions, class II/III obese persons showed lower work capacity and physical quality of life at both baseline and follow-up. Class II/III obese individuals also showed smaller gains in work capacity from baseline to follow-up than all other groups. Further work is needed to identify strategies for improving outcome in obese patients, including incorporating structured weight loss into CR or post-CR referral to an exercise maintenance program.