A comparison of the whole-body and segmental methodologies of bioimpedance analysis

Waist and hip circumference are independently associated with the risk of liver disease in population-based studies

BACKGROUND & AIMS

While several anthropometric measures predict liver disease, the waist-hip ratio (WHR) has shown superiority in previous studies. We analysed independent and joint associations of waist circumference (WC) and hip circumference (HC) with liver disease and liver-related risk factors.

METHODS

Cross-sectional study (n = 6619) and longitudinal cohort (n = 40 923) comprised individuals from Health 2000 and FINRISK 1992-2012 studies. Prevalent and viral liver diseases were excluded. Longitudinal cohort was linked with national healthcare registers for severe incident liver disease. Linear regression and Cox proportional hazards models were used to analyse anthropometric, lifestyle, metabolic and bioimpedance-related parameters; liver enzymes; and 59 liver-related genetic risk variants.

RESULTS

WC and HC showed independent and opposite associations with both liver enzymes and incident liver disease among men (HR for liver disease: WC, 1.07, 95% CI 1.03-1.11; HC, 0.96, 95% CI 0.92-0.99; P-range .04 to <.001) and women (HR for liver diseases: WC, 1.06, 95% CI 1.02-1.10; HC, 0.93, 95% CI 0.89-0.98; P-range .005 to .004). HC modified associations between WC and liver enzymes, and between WC and incident liver disease, particularly among men. Liver enzymes and risk of liver disease increased with increasing WC, more so among individuals with high WHR compared to with low WHR. WC and HC jointly reflected both body fat distribution and muscle mass, which was largely mirrored by WHR.

CONCLUSIONS

WC and HC exhibit independent and joint associations with liver disease, which are largely reflected by WHR. Both body fat distribution and muscle mass contribute to these anthropometric measures.

Whole body and regional phase angle as indicators of muscular performance in athletes

Bioelectrical impedance analysis (BIA)-derived phase angle (PhA) has been used to assess cellular health in various populations, but its usefulness as a tool for measuring muscular performance in adult athletes has not been extensively investigated. Our investigation examined the association of whole-body (WB) PhA with muscular performance in 117 adult athletes from different sports and additionally assessed whether regional PhA was a better indicator of muscular performance compared to WB, while accounting for lean soft tissue (LST). Muscular performance was assessed with handgrip strength and countermovement jump power. WB and regional PhA and LST were obtained by BIA and dual-energy x-ray absorptiometry, respectively. Multiple linear regression was used to model outcomes, while adjusting for LST. WB PhA was positively associated with relative power and relative and absolute strength (p < 0.05), irrespective of LST. Regional PhA measures explained similar amounts of variance in absolute and relative power and strength as that of WB PhA after accounting for age, sex, height, and sport type (lower limb adj R² = 0.42, 0.60 for power; upper limb adj R² = 0.38, 0.74 for strength; WB adj R² = 0.44, 0.63 and 0.38, 0.75 for power and strength, respectively). Only upper limb PhA was related with strength (p < 0.05) after accounting for upper limb LST. PhA may have the potential to be used as a marker of functional muscle mass, which is important when it comes to assessing muscular performance of athletes. Regional measures of PhA do not provide a better indicator of regional strength or power when compared to WB PhA.

The theory and fundamentals of bioimpedance analysis in clinical status monitoring and diagnosis of diseases

Bioimpedance analysis is a noninvasive, low cost and a commonly used approach for body composition measurements and assessment of clinical condition. There are a variety of methods applied for interpretation of measured bioimpedance data and a wide range of utilizations of bioimpedance in body composition estimation and evaluation of clinical status. This paper reviews the main concepts of bioimpedance measurement techniques including the frequency based, the allocation based, bioimpedance vector analysis and the real time bioimpedance analysis systems. Commonly used prediction equations for body composition assessment and influence of anthropometric measurements, gender, ethnic groups, postures, measurements protocols and electrode artifacts in estimated values are also discussed. In addition, this paper also contributes to the deliberations of bioimpedance analysis assessment of abnormal loss in lean body mass and unbalanced shift in body fluids and to the summary of diagnostic usage in different kinds of conditions such as cardiac, pulmonary, renal, and neural and infection diseases.

Can changes in body mass and total body water accurately predict hyponatremia after a 161-km running race?

OBJECTIVE

To relate changes in body mass, total body water (TBW), extracellular fluid (ECF), and serum sodium concentration ([Na]) from a 161-km ultramarathon to finish time and incidence of hyponatremia.

DESIGN

Observational.

SETTING

: The 2008 Rio Del Lago 100-Mile (161-km) Endurance Run in Granite Bay, California.

PARTICIPANTS

Forty-five runners.

MAIN OUTCOME MEASUREMENTS

Pre-race and post-race body mass, TBW, ECF, and serum [Na].

RESULTS

Body mass and serum [Na] significantly decreased 2% to 3% (P < 0.001) from pre-race to post-race, but TBW and ECF were unchanged. Significant relationships were observed between finish time and percentage change in body mass (r = 0.36; P = 0.01), TBW (r = 0.50; P = 0.007), and ECF (r = 0.61; P = 0.003). No associations were found between post-race serum [Na] and percentage change in body mass (r = -0.04; P = 0.94) or finish time (r = 0.5; P = 0.77). Hyponatremia (serum [Na] < 135 mmol/L) was present among 51.2% of finishers. Logistic regression prediction equation including pre-race TBW and percentage changes in TBW and ECF had an 87.5% concordance with the classification of hyponatremia.

CONCLUSIONS

Hyponatremia occurred in over half of the 161-km ultramarathon finishers but was not predicted by change in body mass. The combination of pre-race TBW and percentage changes in TBW and ECF explained 87.5% of the variation in the incidence of hyponatremia.

CLINICAL SIGNIFICANCE

Exercise-associated hyponatremia can occur simultaneously with dehydration and cannot be predicted by weight checks at races.

VO(2max) prediction from multi-frequency bioelectrical impedance analysis

Bioelectrical impedance analysis (BIA) has been shown to be highly related to skeletal muscle mass and blood volume, both of which are important determinants of maximal oxygen uptake (VO(2max)). The aim of the present study was therefore to investigate the ability of whole-body and segmental multi-frequency BIA to improve current nonexercise VO(2max) prediction models. Data for VO(2max) (mL min(-1)), anthropometry, self-reported physical activity (PA-R) and BIA were collected in 115 men and women. Multiple linear regression analysis (MLR) was used to develop the most parsimonious prediction model. Segmental BIA was not superior to whole-body measurements. Correlation coefficients between VO(2max) and resistance indices were significantly higher at 500 kHz compared to 50 kHz (p < 0.05). Intracellular resistance index, however, showed the highest correlation with VO(2max) (r = 0.89). After adjusting for age, gender and PA-R, MLR revealed that the inclusion of intracellular resistance index was slightly, but significantly (p < 0.001), superior to models based on anthropometry. Subgroup analyses indicated that the true benefit of BIA might be most prevalent in subjects with particularly low VO(2max) (<2500 mL min(-1)). In short, whole-body BIA marginally improves the accuracy of nonexercise VO(2max) prediction models and its advantage is most pronounced in individuals with particularly low VO(2max).