Comparison of body composition measurements obtained by two fan-beam DXA instruments

Development and cross-validation of predictive equations for fat-free mass and lean soft tissue mass by bioelectrical impedance in Brazilian women

BACKGROUND/OBJECTIVES

Bioelectrical impedance is one of the most used clinical techniques to assess body composition; however, it is necessary that the available predictive equations are valid for the evaluated subjects. This study aimed to develop and cross-validate equations for fat-free mass (FFM) and lean soft tissue mass (LSTM) by bioelectrical impedance for Brazilian women, in addition to test the validity of other available equations.

SUBJECTS/METHODS

Cross-sectional study with 222 women aged 20-59 years, randomly divided into two groups: development and cross-validation. The standard technique for assessing fat mass, FFM and LSTM was dual energy X-ray absorptiometry. Paired t test, multiple regression, and Bland-Altman plots were used to test the validity of the proposed models, as well as to perform cross-validation of the models.

RESULTS

The equations derived in this study were: FFM = 16.284 + 0.442 × (Height2/Resistance) - 0.13 × age + 0.302 × Weight - 0.121 × Waist Circumference; r2 = 0.86; SEE = 2.32 kg; and LSTM = 14.732 + 0.427 × (Height2/Resistance) - 0.125 × age + 0.291 × Weight - 0.115 × Waist Circumference; r2 = 0.92; SEE = 2.29 kg. In addition, the new equation for FFM showed better agreement when compared to another equation developed for a Brazilian population.

CONCLUSIONS

The newly developed equations provide a valid FFM and LSTM estimation and are recommended for Brazilian women with similar characteristics.

Effects of progressive elastic band resistance exercise for aged osteosarcopenic adiposity women

PURPOSE

Osteosarcopenic adiposity (OSA), which is described as the concurrent occurrence of osteopenia, sarcopenia, and adiposity, can lead to frailty and increase the risk of physical disability in elderly women. Progressive elastic band resistance exercise training (peRET) is considered a safe and feasible exercise intervention for elderly women with sarcopenic obesity. This study investigated the effects of elastic band resistance exercise on the physical capacity and body composition of elderly women with osteosarcopenic adiposity.

METHOD

A total of 15 and 12 women were randomly assigned to the experimental (12 weeks of resistance exercise) and control groups (no exercise intervention), respectively. Lean mass (measured using a dual-energy X-ray absorptiometer) and physical capacity assessments (such as timed up and go test and single leg stance tests) were conducted at baseline, 12 weeks (end of intervention), and 6 months after the intervention. Outcome differences within the study and control groups were analyzed using repeated-measures analysis of variance with a post-hoc test. The Mann-Whitney U test was used to examine differences between groups at different time points.

RESULTS

After the intervention, no body composition changes in muscle mass and fat were observed between the study and control groups. Moreover, muscle mass and fat body composition did not significantly differ at different time points. The bone density was higher in the study group, with a higher T-score than their baseline values, but did not significantly differ compared with the control group. The study group exhibited more improved physical function than the control group, but the effect did not last after 6 months of follow-up.

CONCLUSIONS

A 12-week progressive elastic band resistance training program effectively increased the physical capacity and improved the bone density; however, without persistent training, the positive effect diminished at 6-month follow-up.

Muscular performance and body composition changes following multi-joint versus combined multi- and single-joint exercises in aging adults

The aim of the present study was to compare muscular performance and body composition changes following low-volume resistance-training programs consisting of multi-joint (MJ) exercises (cable chest press and seated row) versus a combination of multi- and single-joint (MJ+SJ) exercises (cable chest press, seated row, biceps curl, and triceps extension). Thirty untrained healthy aging adults were randomly assigned to 3 groups: MJ (n = 11), MJ+SJ (n = 11), and control (n = 8). Twelve-repetition maximums (12-RMs) for the cable chest press and seated row, localized muscular endurance for the elbow flexors handgrip strength, and body composition were assessed before and after the 8-week training program. All comparisons were analyzed via a mixed-model analysis with repeated measures (group × time) and the Bonferroni post hoc test (p < 0.05). The MJ and MJ+SJ groups increased performance in the 12-RM cable chest press (MJ = 61.5% ± 24.6% and MJ+SJ = 71.1% ± 25.6%), 12-RM seated row (MJ = 46.4% ± 26.3% and MJ+SJ = 51.5% ± 21.0%), localized muscular endurance (MJ = 24.7% ± 16.7% and MJ+SJ = 37.0% ± 11.4%), and handgrip strength (MJ = 9.3% ± 10.4% and MJ+SJ = 16.6% ± 25.3%) after the intervention. Body composition (i.e., trunk and upper limb fat and lean mass) did not change for any groups. No significant differences were observed between the MJ versus the MJ+SJ protocols after the intervention for any variables. In conclusion, for aging adults, either MJ or MJ+SJ low-volume resistance training resulted in similar increases in 12-RM, localized muscular endurance, and handgrip strength, without changes in body composition after 8 weeks of training.

Low Relative Lean Mass is Associated with Increased Likelihood of Abdominal Aortic Calcification in Community-Dwelling Older Australians

Age-related loss of skeletal muscle is associated with increased risk of functional limitation and cardiovascular (CV) mortality. In the elderly abdominal aortic calcification (AAC) can increase CV risk by altering aortic properties which may raise blood pressure and increase cardiac workload. This study investigated the association between low muscle mass and AAC in community-dwelling older Australians. Data for this cross-sectional analysis were drawn from a 2010 sub-study of the Melbourne Collaborative Cohort Study in the setting of community-dwelling older adults. Three hundred and twenty-seven participants [mean age = 71 ± 6 years; mean BMI = 28 ± 5 kg/m(2); females n = 199 (62 %)] had body composition determined by dual-energy x-ray absorptiometry (DXA) and AAC determined by radiography. Participants were stratified into tertiles of sex-specific BMI-normalised appendicular lean mass (ALM). Those in the lowest tertile were considered to have low relative muscle mass. Aortic calcification score (ACS) was determined visually as the extent of calcification on the aortic walls between L1 and L4 vertebrae (range: 0-24). Severe AAC was defined as ACS ≥ 6. Prevalence of any AAC was highest in participants with low relative muscle mass (74 %) compared to the middle (65 %) and upper (53 %) tertiles (p trend = 0.006). The lower ALM/BMI tertile had increased odds (Odds ratio = 2.3; 95 % confidence interval: 1.1-4.6; p = 0.021) of having any AAC; and having more severe AAC (2.2; 1.2-4.0; p = 0.009) independent of CV risk factors, serum calcium and physical activity. AAC is more prevalent and severe in community-dwelling older adults with low relative muscle mass. Maintaining muscle mass could form part of a broader primary prevention strategy in reducing AAC.

Assessment of body composition in Indian adults: comparison between dual-energy X-ray absorptiometry and isotope dilution technique

Dual-energy X-ray absorptiometry (DXA) and isotope dilution technique have been used as reference methods to validate the estimates of body composition by simple field techniques; however, very few studies have compared these two methods. We compared the estimates of body composition by DXA and isotope dilution (¹⁸O) technique in apparently healthy Indian men and women (aged 19–70 years, n 152, 48 % men) with a wide range of BMI (14–40 kg/m²). Isotopic enrichment was assessed by isotope ratio mass spectroscopy. The agreement between the estimates of body composition measured by the two techniques was assessed by the Bland–Altman method. The mean age and BMI were 37 (sd 15) years and 23·3 (sd 5·1) kg/m², respectively, for men and 37 (sd 14) years and 24·1 (sd 5·8) kg/m², respectively, for women. The estimates of fat-free mass were higher by about 7 (95 % CI 6, 9) %, those of fat mass were lower by about 21 (95 % CI − 18, − 23) %, and those of body fat percentage (BF%) were lower by about 7·4 (95 % CI − 8·2, − 6·6) % as obtained by DXA compared with the isotope dilution technique. The Bland–Altman analysis showed wide limits of agreement that indicated poor agreement between the methods. The bias in the estimates of BF% was higher at the lower values of BF%. Thus, the two commonly used reference methods showed substantial differences in the estimates of body composition with wide limits of agreement. As the estimates of body composition are method-dependent, the two methods cannot be used interchangeably.

Sarcopenic obesity and dynapenic obesity: 5-year associations with falls risk in middle-aged and older adults

OBJECTIVES

To determine whether obesity concurrent with sarcopenia (low muscle mass) or dynapenia (low muscle strength) is associated with increased falls risk in middle-aged and older adults.

METHODS

5-year prospective cohort study including 674 community-dwelling volunteers (mean ± SD age 61.4 ± 7.0 years; 48% female). Sarcopenia and dynapenia were defined as lowest sex-specific tertiles for dual-energy X-ray (DXA)-assessed appendicular lean mass (adjusted for height and fat mass) or lower-limb strength, respectively. Obesity was defined as the highest tertiles of DXA-assessed total or trunk fat mass. Change in falls risk was calculated using the Physiological Profile Assessment (z-scores: 0-1 = mild increased risk; 1-2 = moderate increased risk; >2 = marked increased risk).

RESULTS

Multivariable linear regression analyses revealed mild but significantly increased falls risk scores for dynapenic obesity (change in mean z-score compared to non-dynapenic, non-obese group: 0.33, 95% CI 0.06-0.59 [men] and 0.46, 95% CI 0.21-0.72 [women]) and dynapenia (0.25, 95% CI 0.05-0.46 [women only]).

CONCLUSIONS

Dynapenic obesity, but not sarcopenic obesity, is predictive of increased falls risk score in middle-aged and older adults. In clinical settings, muscle function assessments may be useful for predicting falls risk in obese patients.

Operational definitions of sarcopenia and their associations with 5-year changes in falls risk in community-dwelling middle-aged and older adults

Sarcopenia may be diagnosed in the clinic using operational definitions based on low muscle mass or function. This prospective, population-based study revealed that sex-specific associations may exist between operational definitions of sarcopenia and falls in community-dwelling middle-aged and older adults.

INTRODUCTION

The objective of this study is to verify associations between sarcopenia and falls risk and to determine changes in sarcopenia prevalence over 5 years in middle-aged and older men and women according to different anthropometric and performance-based operational definitions.

METHODS

N = 681 volunteers (48% female; mean ± SD age 61.4 ± 7.0 years) participated in baseline and follow-up assessments (mean 5.1 ± 0.5 years later). Appendicular lean mass (ALM) was assessed by dual-energy X-ray absorptiometry, hand grip (HGS) and lower-limb (LLS) strength were assessed by dynamometry, and falls risk was determined using the physiological profile assessment. Anthropometric definitions (ALM/height squared [ALM-H], ALM/weight × 100 and a residuals method [ALM-R]) and performance-based definitions (HGS, LLS and upper- and lower-limb muscle quality [LMQ]) of sarcopenia were examined. The lowest 20% of the sex-specific distribution for each definition at baseline was classified as sarcopenia.

RESULTS

Sarcopenia prevalence increased after 5 years for all operational definitions except ALM-H (men: -4.0%; women: -5.5%). Men classified with sarcopenia according to anthropometric definitions, and women classified with sarcopenia according to performance-based definitions, had significant increases in falls risk over 5 years (all P < 0.05) compared to individuals without sarcopenia. Significant sex interactions were observed for ALM-R, LLS and LMQ (all P < 0.05) definitions.

CONCLUSIONS

Sarcopenia prevalence generally increases at a higher rate when assessed using performance-based definitions. Sarcopenia is associated with increases in falls risk over 5 years in community-dwelling middle-aged and older adults, but sex-specific differences may exist according to different anthropometric or performance-based definitions.

Validation of dual energy X-ray absorptiometry measures of abdominal fat by comparison with magnetic resonance imaging in an Indian population

Objective

Abdominal adiposity is an important risk factor for diabetes and cardiovascular disease in Indians. Dual energy X-ray absorptiometry (DXA) can be used to determine abdominal fat depots, being more accessible and less costly than gold standard measures such as magnetic resonance imaging (MRI). DXA has not been fully validated for use in South Asians. Here, we determined the accuracy of DXA for measurement of abdominal fat in an Indian population by comparison with MRI.

Design

146 males and females (age range 18–74, BMI range 15–46 kg/m²) from Hyderabad, India underwent whole body DXA scans on a Hologic Discovery A scanner, from which fat mass in two abdominal regions was calculated, from the L1 to L4 vertebrae (L1L4) and from the L2 to L4 vertebrae (L2L4). Abdominal MRI scans (axial T1-weighted spin echo images) were taken, from which adipose tissue volumes were calculated for the same regions.

Results

Intra-class correlation coefficients between DXA and MRI measures of abdominal fat were high (0.98 for both regions). Although at the level of the individual, differences between DXA and MRI could be large (95% of DXA measures were between 0.8 and 1.4 times MRI measures), at the sample level, DXA only slightly overestimated MRI measures of abdominal fat mass (mean difference in L1L4 region: 2% (95% CI:0%, 5%), mean difference in L2L4 region:4% (95% CI: 1%, 7%)). There was evidence of a proportional bias in the association between DXA and MRI (correlation between difference and mean −0.3), with overestimation by DXA greater in individuals with less abdominal fat (mean bias in leaner half of sample was 6% for L1L4 (95%CI: 2, 11%) and 7% for L2L4 (95% CI:3,12%).

Conclusions

DXA measures of abdominal fat are suitable for use in Indian populations and provide a good indication of abdominal adiposity at the population level.

Relationship between obesity and physical fitness and periodontitis

BACKGROUND

Obesity and exercise are important elements associated with lifestyle-related diseases, and studies suggested that these factors may also be related to periodontitis. This study investigates the relationship between obesity and physical fitness and periodontitis.

METHODS

One thousand, one hundred and sixty Japanese subjects, aged 20 to 77 years, who participated in health examinations at Fukuoka Health Promotion Center were analyzed. Periodontal conditions were evaluated using the Community Periodontal Index (CPI), and subjects with > or =3 sextants of CPI code 3 or 4 were defined as having severe periodontitis. We used the body mass index (BMI) and percentage of body fat as indicators of obesity and estimated the maximal oxygen consumption (VO(2max)) during exercise as an indicator of physical fitness. We divided these variables into quintiles. We examined the single effect and interactions of the obesity index and VO(2max) on severe periodontitis.

RESULTS

The lowest quintile in BMI and the highest quintile in VO(2max) were inversely associated with severe periodontitis, singly, in multivariate logistic regression analyses. Subjects with the combined lowest quintile in BMI and the highest quintile in VO(2max) had a significantly lower risk of severe periodontitis compared to subjects with other combined quintiles in BMI and in VO(2max) (odds ratio: 0.17; 95% confidence interval: 0.05 to 0.55).

CONCLUSION

This study suggests that obesity and physical fitness may have some interactive effect on periodontal health status.

Bone cross-sectional geometry in adolescents and young women with anorexia nervosa: a hip structural analysis study

INTRODUCTION

Better characterization of bone geometry in adolescents with anorexia nervosa (AN) may improve understanding of skeletal deficits in this population. Our objective was to determine whether hip cross-sectional geometry and bone strength were altered in adolescents with AN.

METHODS

Measurements of the left total proximal femur and body composition were obtained in 85 adolescents with AN and 61 healthy controls by dual X-ray absorptiometry. The Hip Structural Analysis (HSA) program was used to determine aBMD, cross-sectional area (CSA), and section modulus (Z) at the femoral neck and shaft. Strength indices were calculated and corrected for lean mass.

RESULTS

Femoral neck and shaft aBMD were lower in AN patients than healthy controls (-36% and -29%, p < 0.001). In both regions, bone CSA and Z were lower in AN sufferers (-11 to -35%, p < 0.001). While lean body mass correlated with HSA variables (r = 0.48 to 0.58, p < 0.001), body fat did not. AN sufferers had lower indices of both whole bone strength (-40%, p < 0.001) and relative bone strength (-36%, p < 0.001) than controls.

CONCLUSIONS

Anorexia nervosa sufferers had decreased resistance to axial (CSA) and bending loads (Z) compared with healthy controls. Differences in strength properties were significant even when adjusted for lean mass, suggesting that not only decreased mechanical loading, but also known metabolic differences are likely responsible for deficits in bone strength in these patients.