Validation of the two-minute step test in obese with comorbibities and morbidly obese patients.

Cardiopulmonary fitness assessment is a valuable resource to obtain quantitative indicators of an individual's physical performance. The cardiopulmonary exercise test (CPX), considered the gold standard test for this evaluation, is costly and difficult to be accessed by the general population. In order to make this evaluation more accessible, and to better reflect the performance of daily life activities, alternative tests were proposed. Morbidly obese patients present limitations that impair physical performance assessment and could benefit from a test of shorter duration, provided it is validated. This observational study aimed to validate the two-minute step test (2MST) as a tool to evaluate functional capacity (FC) in obese with comorbidities and morbidly obese patients, compared the 2MST with CPX as a measure of physical performance, and developed a predictive equation to estimate peak oxygen uptake (VO2) in the 2MST. The CPX and the 2MST were performed and metabolic and ventilatory parameters were recorded in 31 obese individuals (BMI>35 kg/m2). Pearson correlation and multiple linear regression analyses were performed to evaluate the peak VO2 best predictors. Bland-Altman analysis was performed to assess the agreement between the two methods. Peak VO2 measured by CPX and 2MST showed a strong correlation (r=0.70, P<0.001) and there was a moderate correlation between peak VO2 of the 2MST and the number of up-and-down step cycles (UDS) (r=0.55; P=0.01). The reference equation obtained was: VO2 (mL·kg-1·min-1) = 13.341 + 0.138 × total UDS - (0.183 × BMI), with an estimated standard error of 1.3 mL·kg-1·min-1. The 2MST is a viable, practical, and easily accessible test for FC. UDS and BMI can predict peak VO2 satisfactorily.

Validation of the two-minute step test in obese with comorbibities and morbidly obese patients

Cardiopulmonary fitness assessment is a valuable resource to obtain quantitative indicators of an individual's physical performance. The cardiopulmonary exercise test (CPX), considered the gold standard test for this evaluation, is costly and difficult to be accessed by the general population. In order to make this evaluation more accessible, and to better reflect the performance of daily life activities, alternative tests were proposed. Morbidly obese patients present limitations that impair physical performance assessment and could benefit from a test of shorter duration, provided it is validated. This observational study aimed to validate the two-minute step test (2MST) as a tool to evaluate functional capacity (FC) in obese with comorbidities and morbidly obese patients, compared the 2MST with CPX as a measure of physical performance, and developed a predictive equation to estimate peak oxygen uptake (VO2) in the 2MST. The CPX and the 2MST were performed and metabolic and ventilatory parameters were recorded in 31 obese individuals (BMI>35 kg/m2). Pearson correlation and multiple linear regression analyses were performed to evaluate the peak VO2 best predictors. Bland-Altman analysis was performed to assess the agreement between the two methods. Peak VO2 measured by CPX and 2MST showed a strong correlation (r=0.70, P<0.001) and there was a moderate correlation between peak VO2 of the 2MST and the number of up-and-down step cycles (UDS) (r=0.55; P=0.01). The reference equation obtained was: VO2 (mL·kg-1·min-1) = 13.341 + 0.138 × total UDS - (0.183 × BMI), with an estimated standard error of 1.3 mL·kg-1·min-1. The 2MST is a viable, practical, and easily accessible test for FC. UDS and BMI can predict peak VO2 satisfactorily.

Influence of menopausal status on the main contributors of muscle quality.

BACKGROUND: Muscle quality is a strong independent predictor of physical function. Body mass and fatness, muscle mass and cardiorespiratory fitness are known to influence muscle quality. OBJECTIVE: To identify the contributors of muscle quality in young and postmenopausal women and whether hormone replacement therapy (HT) could influence this relationship at the age of menopause. METHODS: Fifty-four postmenopausal women, 27 not on HT (PMW) and 27 on HT (PMW-HT), and 33 young women (YW) were evaluated for (1) body composition (body mass index, BMI), total fat mass (FM, %), appendicular lean mass (ALM, in kg and %), and appendicular skeletal mass index (ASMI = ALM/height2 in kg/m2); (2) absolute peak oxygen uptake (VO2peak, in ml/min) and relative peak oxygen uptake (VO2peakRel in ml/kg/min); and (3) absolute isometric knee extension strength (iKES in kg) and relative isometric knee extension strength (iKES/BMI and iKES/ALM). RESULTS: YW, PMW and PMW-HT had similar BMI (32.1 ± 10.2, 27.3 ± 4.7 and 26.7 ± 4 kg/m2) and FM (39.8 ± 10.0, 39.8 ± 7.3 and 39.9 ± 7.1%), respectively. Correlations were found between iKES/BMI index and FM (r = -0.52), ALM (r = 0.32) and VO2peak (r = 0.31). Regression analysis demonstrated that, in YW, total amount of variance in iKES/BMI was mostly explained by ALM (42%), whereas, in PMW and PMW-HT, it was cumulatively explained by FM along with VO2peakRel (34 and 46%, respectively). CONCLUSION: The main contributors of muscle quality differ between young and postmenopausal women and HT does not seem to influence this relationship.

Does the incremental shuttle walk test require maximal effort in young obese women?

Obesity is a chronic disease with a multifaceted treatment approach that includes nutritional counseling, structured exercise training, and increased daily physical activity. Increased body mass elicits higher cardiovascular, ventilatory and metabolic demands to varying degrees during exercise. With functional capacity assessment, this variability can be evaluated so individualized guidance for exercise training and daily physical activity can be provided. The aim of the present study was to compare cardiovascular, ventilatory and metabolic responses obtained during a symptom-limited cardiopulmonary exercise test (CPX) on a treadmill to responses obtained by the incremental shuttle walk test (ISWT) in obese women and to propose a peak oxygen consumption (VO2) prediction equation through variables obtained during the ISWT. Forty obese women (BMI ≥30 kg/m2) performed one treadmill CPX and two ISWTs. Heart rate (HR), arterial blood pressure (ABP) and perceived exertion by the Borg scale were measured at rest, during each stage of the exercise protocol, and throughout the recovery period. The predicted maximal heart rate (HRmax) was calculated (210 - age in years) (16) and compared to the HR response during the CPX. Peak VO2 obtained during CPX correlated significantly (P<0.05) with ISWT peak VO2 (r=0.79) as well as ISWT distance (r=0.65). The predictive model for CPX peak VO2, using age and ISWT distance explained 67% of the variability. The current study indicates the ISWT may be used to predict aerobic capacity in obese women when CPX is not a viable option.

Does the incremental shuttle walk test require maximal effort in young obese women?

Obesity is a chronic disease with a multifaceted treatment approach that includes nutritional counseling, structured exercise training, and increased daily physical activity. Increased body mass elicits higher cardiovascular, ventilatory and metabolic demands to varying degrees during exercise. With functional capacity assessment, this variability can be evaluated so individualized guidance for exercise training and daily physical activity can be provided. The aim of the present study was to compare cardiovascular, ventilatory and metabolic responses obtained during a symptom-limited cardiopulmonary exercise test (CPX) on a treadmill to responses obtained by the incremental shuttle walk test (ISWT) in obese women and to propose a peak oxygen consumption (VO2) prediction equation through variables obtained during the ISWT. Forty obese women (BMI ≥30 kg/m2) performed one treadmill CPX and two ISWTs. Heart rate (HR), arterial blood pressure (ABP) and perceived exertion by the Borg scale were measured at rest, during each stage of the exercise protocol, and throughout the recovery period. The predicted maximal heart rate (HRmax) was calculated (210 – age in years) (16) and compared to the HR response during the CPX. Peak VO2 obtained during CPX correlated significantly (P<0.05) with ISWT peak VO2 (r=0.79) as well as ISWT distance (r=0.65). The predictive model for CPX peak VO2, using age and ISWT distance explained 67% of the variability. The current study indicates the ISWT may be used to predict aerobic capacity in obese women when CPX is not a viable option.

The six-minute step test as a predictor of cardiorespiratory fitness in obese women.

BACKGROUND: The impaired cardiorespiratory fitness (CRF) status is a hallmark in obese individuals, especially in women around the world. Some field tests have been proposed to evaluate functional capacity in this population. The Six-Minute Step Test (6MST) could be a feasible alternative to cardiopulmonary exercise testing (CPX) if the resources and space are limited. However, an optimal performance cutoff using the 6MST as well as predictive equations of metabolic and cardiovascular responses to CPX from 6MST data have to not been established. AIM: To assess the 6MST accuracy to determinate CRF and its ability to predict peak oxygen consumption (VO2) and heart rate (HR) achieved during CPX in sedentary obese women. DESIGN: Observational and cross-sectional study. SETTING: The study was performed at a Physiotherapy Department of a public University and enrolled individuals from the community. POPULATION: Fifty-six obese women (35±7 years old). METHODS: Subjects underwent a clinical evaluation, CPX, and the 6MST. We applied Bland-Altman plots to assess concurrent validity between exercise tests regarding peak VO2 and HR. Receiver operating characteristic curve analysis and stepwise multiple linear regression analysis assessed the predictive accuracy of the 6MST; specifically the ability to predict peak VO2 and HR achieved during CPX. Significance level was P<0.05. RESULTS: There was a satisfactory concurrent validity between the CPX and 6MST, with a mean difference of 5.1±3.6 mL·kg-1·min-1 and 23±13 bpm in relation to peak VO2 and HR, respectively. The 6MST demonstrated moderate accuracy in predicting CPX responses (area under the curve: 0.72, 95% CI: 0.59-0.83). The number of step cycles and peak HR during the 6MST explained 31% and 39% of the total variance in peak VO2 and HR obtained during CPX, respectively. CONCLUSION: The 6MST is accurate to discriminate obese women with an adequate CRF from women with a poor status and it can predict metabolic and cardiovascular maximal exercise values. CLINICAL REHABILITATION IMPACT: Our findings indicate the 6MST is a simple and inexpensive functional evaluation tool and may be a valid means of assessing CRF in sedentary obese women, particularly in clinical settings where space and resources are limited.