Validation of a Multielectrode Bioelectrical Impedance Analyzer With a Dual-Energy X-Ray Absorptiometer for the Assessment of Body Composition in Older Adults.

Changes in body composition are related to mobility, fall risk, and mortality, especially in older adults. Various devices and methods exist to measure body composition, but bioelectrical impedance analysis (BIA) has several advantages. The purpose of this study was to validate a common BIA device with a dual-energy X-ray absorptiometer (DXA) in older adults and develop prediction equations to improve the accuracy of the BIA measurements. The participants were 277 older adults (162 women and 115 men; age 73.9 ± 5.8 years) without a history of cancer and without a history of severe medical or mental conditions. Individuals fasted 12 hr before BIA and DXA measurement. The correlations between the two methods for appendicular lean mass (ALM), fat-free mass (FFM), and percentage body fat (%BF) were .86, .93, and .92, respectively, adjusting for age and sex. The mean percentage error (DXA-InBody) and mean absolute percentage error were -12% and 13% for ALM, -13% and 13% for FFM, and 16% and 17% for %BF. The prediction equations estimated ALM, FFM, and %BF; sex was coded as 1 for male and 0 for female: DXAALM=0.0673+(0.6732×BIAALM)+(2.33507×sex)+(0.13349×BMI),R2=.94; DXAFFM=0.72323+(0.72384×BIAFFM)+(3.675012×sex)+(0.2816×BMI),R2=.97; and DXA%BF=15.8896+(0.64694×BIA%BF) -(3.99945×sex)+(0.13824×BMI),R2=.91 Although highly correlated, BIA overestimated FFM, and ALM and underestimated %BF compared with DXA. An application of prediction equations eliminated the mean error and reduced the range of individual error across the sample. Prediction equations may improve BIA accuracy sufficiently to substitute for DXA in some cases.

Physical activity and sarcopenic obesity: definition, assessment, prevalence and mechanism.

Sarcopenic obesity is the coexistance of sarcopenia and obesity. Modern sarcopenia definition includes low muscle mass, weak muscle strength (handgrip strength) and poor physical function (slow walking), although the clinical definition of each varies worldwide. The cut-points for low muscle mass for men and women using appendicular lean mass divided by height (kg/m2) are ≤7.0 and ≤5.4 in Asians, and ≤7.23 and ≤5.67 in Caucasians, respectively. The cut-points for weak handgrip strength (kg) for men and women are <26 and <18 in Asians, and <30 and <20 in Caucasians, respectively. The cut-point for slow walking is ≤0.8 m/s in men and women. Current data suggest the potential benefits of physical activity and fitness on sarcopenic obesity in older adults.

Longitudinal cardiorespiratory fitness algorithms for clinical settings.

BACKGROUND: Non-exercise algorithms are cost-effective methods to estimate cardiorespiratory fitness (CRF) in healthcare settings. The limitation of current non-exercise models is that they were developed with cross-sectional data. PURPOSE: To extend the non-exercise research by developing algorithms for men and women using longitudinal data on indicators available in healthcare settings. METHODS: The sample included 1325 women (aged 20-78 years) and 10,040 men (aged 20-86 years) who completed two to 21 maximal treadmill tests between 1977 and 2005. The data were analyzed in 2011 and 2012. The dependent variable was CRF measured by treadmill test. The independent variables were age; body composition (percentage fat or BMI); waist circumference; self-reported physical activity; resting heart rate; and smoking behavior. RESULTS: Linear mixed-models regression showed that all variables were independently related to CRF. There was a positive association between CRF and physical activity. Higher levels of body composition were linked to lower CRF. High resting heart rate and smoking resulted in lower estimates of CRF. The error estimates of the percentage fat algorithms were as follows: women, 1.41 METs (95% CI=1.35, 1.47); and men, METs 1.54 (95% CI=1.51, 1.55). The BMI models were somewhat less accurate: women, METs 1.51 (95% CI=1.45, 1.58); and men, 1.66 METs (95% CI=1.63, 1.68). CONCLUSIONS: These results showed that the CRF of women and men can be estimated from easily obtained health indicators. The longitudinal non-exercise algorithms provide models to accurately estimate CRF changes associated with aging and provide cost-effective algorithms to track CRF over time with health indicators available in healthcare settings.

Ideal cardiovascular health and mortality: Aerobics Center Longitudinal Study.

OBJECTIVE: To analyze the relationship of ideal cardiovascular health to disease-specific death. PATIENTS AND METHODS: We used data from the Aerobics Center Longitudinal Study from October 9, 1987, to March 3, 1999, to estimate the prevalence of ideal cardiovascular health in 11,993 individuals (24.3% women) and to examine its relationship with deaths from all causes, cardiovascular disease (CVD), and cancer. RESULTS: During a mean follow-up of 11.6 years, 305 deaths occurred: 70 (23.0%) from CVD and 127 (41.6%) from cancer. In the entire cohort, only 29 individuals (0.2%) had 7 ideal metrics. After adjusting for age, sex, examination year, alcohol intake, and parental history of CVD, risk of death due to CVD was 55% lower in those participants who met 3 or 4 ideal metrics (hazard ratio, 0.45; 95% confidence interval, 0.27-0.77) and 63% lower in those with 5 to 7 ideal metrics (hazard ratio, 0.37; 95% confidence interval, 0.15-0.95), compared with those who met 0 to 2 ideal metrics. Although not significant, there was also a trend toward lower risk of death due to all causes across incremental numbers of ideal metrics. No association was observed for deaths due to cancer. CONCLUSION: The prevalence of ideal cardiovascular health was extremely low in a middle-aged cohort of men and women recruited between 1987 and 1999. The American Heart Association construct reflects well the subsequent risk of CVD, as reflected by graded CVD mortality in relation to the number of ideal metrics.

Farming activities and carrying and lifting: the Agricultural Health Study.

BACKGROUND: Heavy carrying and lifting (HCL) is a common activity among farmers that may be related to health. The aim of this study was to examine HCL as a proxy for occupational physical activity (PA) among farm residents. The secondary objective was to evaluate PA based on HCL. METHODS: Data from 21,296 farmers and 30,951 spouses in the Agricultural Health Study examined the relationship between HCL and farm activities and individual/farm characteristics. HCL was categorized as ≥ 1 or < 1 hours per day. The association between HCL and farm activities (15 for farmers; 16 for spouses) and individual/farm characteristics was examined using adjusted logistic regression. To evaluate PA, we created a PA activity index using metabolic equivalents for HCL, and compared PA weekly averages with national guidelines. RESULTS: In adjusted results, most farm activities were significantly associated with HCL. Based on HCL, farmers had a median of 1.5 hours and spouses 0.5 hours of vigorous or muscle-strengthening PA per day. Most farmers (94%) and about 60% of spouses meet or exceed 2008 national guidelines for vigorous or muscle-strengthening PA. CONCLUSION: Findings suggest the HCL measure may be useful as a PA metric in future studies of occupational PA among farm residents.

In fitness and health? A prospective study of changes in marital status and fitness in men and women.

The authors examined the prospective associations between marital status transitions and changes in fitness in men and women. Between 1987 and 2005, a total of 8,871 adults (6,900 men) aged 45.6 (standard deviation, 9.1) years were examined at the Cooper Clinic, Dallas, Texas; the median follow-up was ∼3 years. Marital transition categories (from single to married, married to divorced, divorced to remarried) were derived from self-reported marital status at baseline and follow-up. Fitness (maximal oxygen consumption) was assessed by a maximal treadmill test. Analyses were adjusted for baseline levels and changes in body mass index, physical activity, smoking, alcohol consumption, and major chronic diseases. Compared with the corresponding "control" groups (remaining single, married, or divorced), transitioning from being single to married was associated with a reduction in fitness in women (P = 0.03); divorce was associated with an increase in fitness in men (P = 0.04); and remarriage was associated with a reduction in fitness in men (P = 0.05). The authors conclude that the transitions to being married (from single to married or from divorced to remarried) are associated with a modest reduction, while divorce is associated with a modest increase in fitness levels in men. Study results suggest that these patterns may be different in women, but further research is required to confirm this.