Disability Affects the 6-Minute Walking Distance in Obese Subjects (BMI>40 kg/m)

Department of Experimental Medicine-Medical Physiopathology, Food Science and Endocrinology Section, "Sapienza" University of Rome, Rome, Italy.
PLoS ONE (Impact Factor: 3.23). 10/2013; 8(10):e75491. DOI: 10.1371/journal.pone.0075491
Source: PubMed


In obese subjects, the relative reduction of the skeletal muscle strength, the reduced cardio-pulmonary capacity and tolerance to effort, the higher metabolic costs and, therefore, the increased inefficiency of gait together with the increased prevalence of co-morbid conditions might interfere with walking. Performance tests, such as the six-minute walking test (6MWT), can unveil the limitations in cardio-respiratory and motor functions underlying the obesity-related disability. Therefore the aims of the present study were: to explore the determinants of the 6-minute walking distance (6MWD) and to investigate the predictors of interruption of the walk test in obese subjects.

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    • "The included subjects were free from chronic diseases, although 9.5% of them showed moderate obesity or were underweight. Subjects with marked or extreme obesity were not included [11] [13] [17] [21] [24] because it is known that obese subjects with BMI > 35 kg/m 2 tend to walk slower [58] and it seems that specific 6MWD norms for obese subjects are needed [59]. In addition, 9.1% of the Algerian adults show obesity [60], and the present study group composition reflected this ''healthy " population as they exist in the real population, increasing the external validity of the retained norms. "
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    ABSTRACT: Background. In North-African and Mediterranean countries (such as Algeria, Tunisia, Morocco, Libya) no local 6-min walk-distance (6MWD) norms exist for subjects aged 16-40 years. Aims. i) To test the applicability and reliability of the previously published norms for Arab or Mediterranean subjects aged ≥ 16 years in this population and, if required, ii) To establish a 6MWD reference equation for use in North-African subjects aged 16-40 years and prospectively assess its reliability and to propose a clear scheme to interpret the measured 6MWD. Study design. Prospective cross-sectional study Methods. Metabolic-equivalent-task (MET) walking, moderate, and vigorous activities, anthropometric, spirometric and 6-min walk-test (6MWD, heart-rate, oxy-haemoglobin-saturation) data were measured/noted in 200 healthy Algerian subjects aged 16 to 40 years (100 women). Univariate and multiple linear regression analyses were used to find-out 6MWD influencing factors, reference equation and to determine the lower-limit-of-normal (LLN). Results. The mean±SD of 200 included subjects’ age, height, weight, body-mass-index (BMI), lean-mass, first-second-forced-expiratory-volume (FEV1) and MET moderate activity were, respectively, 27.5±6.7 years, 169±9 cm, 69.3±11.5 kg, 24.1±3.6 kg/m2, 16.7±7.4 kg, 3.70±0.74 L and 370±686 min/week. Their 6MWD mean±SD (minimum-maximum) was 680±70 (540-888) m. The published norms for Italian and Saudi-Arabian populations did not reliably predict measured 6MWD. The following 6MWD influencing factors were noted: FEV1, BMI, sex, lean-mass, MET moderate activity and age (p<0.001). A reference equation, explaining 58.7% of the 6MWD variability, was established: 6MWD (m) = 800.05 + 64.71 × Sex (men:1/women:0) - 10.23 × BMI (kg/m2) - 1.63 × Age (years) + 2.05 × Weight (kg). To calculate the 6MWD LLN subtract 74.31 m from the predicted value. In a second group of 39 young subjects (19 women) prospectively studied to validate the reference equation, the agreement between the measured and predicted 6MWDs was adequate. Conclusion. This reliable 6MWD norm is helpful for the care of North-African patients aged 16 to 40 years.
    Full-text · Article · Aug 2015
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    ABSTRACT: Obesity is associated with mobility reduction due to mechanical factors and excessive body fat. The six-minute walk test (6MWT) has been used to assess functional capacity in severe obesity. To determine the association of BMI, total and segmental body composition with distance walked (6MWD) during the six-minute walk test (6MWT) according to gender and obesity grade. University of São Paulo Medical School, Brazil; Public Practice. Functional capacity was assessed by 6MWD and body composition (%) by bioelectrical impedance analysis in 90 patients. The mean 6MWD was 514.9 ± 50.3 m for both genders. The male group (M: 545.2 ± 46.9 m) showed a 6MWD higher (p = 0.002) than the female group (F: 505.6 ± 47.9 m). The morbid obese group (MO: 524.7 ± 44.0 m) also showed a 6MWD higher (p = 0.014) than the super obese group (SO: 494.2 ± 57.0 m). There was a positive relationship between 6MWD and fat free mass (FFM), FFM of upper limps (FFM_UL), trunk (FFM_TR) and lower limbs (FFM_LL). Female group presented a positive relationship between 6MWD and FFM, FFM_UL and FFM_LL and male group presented a positive relationship between 6MWD and FFM_TR. In morbid obese group there was a positive relationship between 6MWD with FFM, FFM_UL, FFM_TR and FFM_LL. The super obese group presented a positive relationship between 6MWD with FFM, FFM_TR and FFM_LL. Total and segmental FFM is associated with a better walking capacity than BMI.
    Full-text · Article · Jun 2015 · PLoS ONE
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    ABSTRACT: The prevalence of childhood obesity has risen considerably on a global scale during the past decades, and the condition is associated with increased risk of morbidity. The objective is to describe the Uppsala Longitudinal Study of Childhood Obesity (ULSCO) cohort, including some baseline data, and outline addressed research areas that aim at identifying factors implicated in and contributing to development of obesity and obesity-related diseases, including type 2 diabetes. Severely obese and lean control subjects are examined at enrollment and at subsequent annual visits by using detailed questionnaires, anthropometric measurements, indirect calorimetry, and functional tests such as oral glucose tolerance tests. Some subjects undergo additional characterization with MRI, subcutaneous fat biopsies, frequent blood sampling, and hyperglycemic clamps. Biological samples are obtained and stored in a biobank. Active recruitment started in 2010, and standard operating procedures have been established. A high participation rate and annual follow-ups have resulted in a cohort exceeding 200 subjects, including 45 lean controls (as of October 2013). Initial research focus has been on traits of the metabolic syndrome, hyperinsulinemia and identifying risk factors for type 2 diabetes. The ULSCO cohort serves as an important resource in defining and understanding factors contributing to childhood obesity and development of obesity-related diseases. Given the comprehensive characterization of the cohort, factors contributing to disease development and progression can be identified. Such factors are further evaluated for their mechanistic role and significance, and noncommunicable metabolic diseases are especially addressed and considered.
    Preview · Article · Jan 2014 · PEDIATRICS
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