Association between ICW/TBW ratio and cancer prognosis: Subanalysis of a population-based retrospective multicenter study.

BACKGROUND & AIMS: Disease burden is known to alter cellular integrity and water balance. Therefore, the intracellular water/total body water (ICW/TBW) ratio is used as an adjunctive indicator to predict disease severity and prognosis. The ICW/TBW ratio of patients with cancer, who typically present with low muscle mass, poor nutritional status, and high inflammatory response, reportedly differs from that of the healthy population. Herein, we aimed to evaluate the effect of the ICW/TBW ratio on the prognosis of different subgroups of patients with cancer. METHODS: This multicenter cohort study included 2787 patients with malignancies between June 2014 and December 2018. The association between covariates and overall survival (OS) was assessed using restricted cubic spline models. The multivariate Cox regression model included variables demonstrating a statistical significance in the univariate Cox regression analysis (P < 0.05) without multicollinearity. The generated nomogram used the C-index and calibration curves to validate the predictive accuracy of the scoring system. RESULTS: The optimal cut-off value for the ICW/TBW ratio was 0.61. The ICW/TBW ratio was an independent prognostic factor (hazard ratio [HR]: 0.621; 95 % confidence interval [CI]: 0.537-0.719, P < 0.001). Moreover, the ICW/TBW ratio had a greater impact on the prognosis of patients receiving chemoradiotherapy than on those receiving chemotherapy alone (chemoradiotherapy: HR = 0.495, P = 0.005 vs. chemotherapy: HR = 0.646, P < 0.001). Multivariate Cox regression analysis showed that sex, age, tumor stage, body mass index, neutrophil-to-lymphocyte ratio (NLR), and ICW/TBW ratio were associated with OS. Subsequently, a nomogram was developed incorporating these variables and yielded a C-index of 0.743. CONCLUSIONS: The ICW/TBW ratio was associated with muscle mass, nutritional status, and inflammation. A low ICW/TBW ratio is an independent risk factor for poor prognosis in patients with cancer, especially when they are female, have advanced cancer stage, have sarcopenia, and are receiving radiotherapy.

Body Cell Mass to Fat-Free Mass Ratio and Extra- to Intracellular Water Ratio Are Related to Maximal Oxygen Uptake.

Fat-free mass (FFM) is a heterogeneous compartment comprising body cell mass (BCM), intracellular water (ICW), extracellular solids, and extracellular water (ECW). The BCM/FFM and ECW/ICW ratios vary among individuals and decrease with age. This study aimed to determine whether BCM/FFM and ECW/ICW ratios are predictors of maximal oxygen uptake (V̇̇O2peak) independently of age, sex, and objectively measured physical activity (PA). A total of 115 Japanese males and females, aged 55.3 ± 8.0 years (mean ± standard deviation), were included in the study. Anthropometry, explosive leg muscle power, and V̇̇O2peak were measured, and BCM, FFM, ICW, and ECW were estimated. Step count and PA were objectively measured using a triaxial accelerometer. Blood flow volume was assessed using ultrasonography. BCM and ICW were negatively correlated with age, whereas FFM and ECW were not significantly correlated with age. FFM, ICW/ECW, BCM/FFM, step counts, moderate and vigorous PA, and leg muscle power were positively correlated with V̇̇O2peak, even after adjusting for age and sex (p < .05). Multiple regression analysis indicated that either BCM/FFM or ECW/ICW, leg power, and objectively measured PA were associated with V̇̇O2peak independent of age, sex, and FFM. Blood flow volume was significantly correlated with ECW (p < .05), but not with BCM. The BCM/FFM and ECW/ICW ratios were significant predictors of V̇̇O2peak, independent of age, sex, FFM, leg power, and objectively measured PA.

Athletes with different habitual fluid intakes differ in hydration status but not in body water compartments.

Physiological differences have been reported between individuals who have habitual low (LOW) and high (HIGH) water intake (WI). The aims of this study were to explore body water compartments, hydration status, and fat-free mass (FFM) hydration of elite athletes exposed to different habitual WI. A total of 68 athletes (20.6 ± 5.3 years, 23 females) participated in this observational cross-sectional study. Total WI was assessed by seven-day food diaries and through WI, athletes were categorized as HIGH (n = 28, WI≥40.0 mL/kg/d) and LOW (n = 40, WI≤35.0 mL/kg/d). Total body water (TBW) and extracellular water (ECW) were determined by dilution techniques and intracellular water (ICW) as TBW-ECW. Hydration status was assessed by urine-specific gravity (USG) using a refractometer. Fat (FM) and FFM were assessed by dual-energy X-ray absorptiometry (DXA). The FFM hydration was calculated by TBW/FFM. The USG was statistically different between groups for females (LOW: 1.024 ± 0.003; HIGH: 1.015 ± 0.006; p = 0.005) and males (LOW: 1.024 ± 0.002; HIGH: 1.018 ± 0.005; p < 0.001). No differences between groups were detected in body water compartments and FFM hydration in both sexes (p > 0.05). Multiple regression showed that WI remains a predictor of USG regardless of FFM, age, and sex (ß = -0.0004, p < 0.01). We concluded that LOW athletes were classified as dehydrated through USG although their water compartments were not different from HIGH athletes. These results suggest that LOW athletes may expectedly maintain the body water compartments' homeostasis through endocrine mechanisms. Interventions should be taken to encourage athletes to have sufficient WI to maintain optimal hydration.

Assessing Tissue Hydration Dynamics Based on Water/Fat Separated MRI.

BACKGROUND: Optimal fluid status is an important issue in hemodialysis. Clinical evaluation of volume status and different diagnostic tools are used to determine hydration status in these patients. However, there is still no accurate method for this assessment. PURPOSE: To propose and evaluate relative lean water signal (LWSrel ) as a water-fat MRI-based tissue hydration measurement. STUDY TYPE: Prospective. POPULATION: A total of 16 healthy subjects (56 ± 6 years, 0 male) and 11 dialysis patients (60.3 ± 12.3 years, 9 male; dialysis time per week 15 ± 3.5 hours, dialysis duration 31.4 ± 27.9 months). FIELD STRENGTH/SEQUENCE: A 3 T; 3D spoiled gradient echo. ASSESSMENT: LWSrel , a measurement of the water concentration of tissue, was estimated from fat-referenced MR images. Segmentations of total adipose tissue as well as thigh and calf muscles were used to measure LWSrel and tissue volumes. LWSrel was compared between healthy subjects and dialysis patients, the latter before and after dialysis. Bioimpedance-based body composition monitor over hydration (BCM OH) was also measured. STATISTICAL TESTS: T-tests were used to compare differences between the healthy subjects and dialysis patients, as well as changes between before and after dialysis. Pearson correlation was calculated between MRI and non-MRI biomarkers. A P value <0.05 was considered statistically significant. RESULTS: The LWSrel in adipose tissue was significantly higher in the dialysis cohort compared with the healthy cohort (246.8% ± 60.0% vs. 100.0% ± 10.8%) and decreased significantly after dialysis (246.8 ± 60.0% vs. 233.8 ± 63.4%). Thigh and calf muscle volumes also significantly decreased by 3.78% ± 1.73% and 2.02% ± 2.50% after dialysis. There was a significant correlation between changes in adipose tissue LWSrel and ultrafiltration volume (r = 87), as well as with BCM OH (r = 0.66). DATA CONCLUSION: MRI-based LWSrel and tissue volume measurements are sensitive to tissue hydration changes occurring during dialysis. EVIDENCE LEVEL: 2. TECHNICAL EFFICACY: Stage 3.

Extracellular water-to-total body water ratio is an essential confounding factor in bioelectrical impedance analysis for sarcopenia diagnosis in women.

PURPOSE: The extracellular water-to-total body water ratio (ECW/TBW) is used in bioelectrical impedance analysis (BIA) for measuring muscle mass; however, ECW/TBW may be affected by several factors common in older individuals. Here, we assessed the relationships of ECW/TBW with handgrip strength, gait speed, and skeletal muscle mass index (SMI) in older women. METHODS: In this cross-sectional study, 73 community-dwelling women aged ≥ 65 years who could independently perform activities of daily living were included. ECW/TBW was measured using direct segmental multifrequency BIA. The participants were divided into ECW/TBW < 0.40 (n = 54) and ECW/TBW ≥ 0.40 (n = 19) groups, with the latter indicating overhydration. SMI was calculated as appendicular skeletal muscle mass/(height)2 (kg/m2). The relationships of SMI with handgrip strength and gait speed were assessed using partial correlation coefficients. Age, number of medications, pain, and medical history were treated as control variables. RESULTS: The average age of participants was 77.6 ± 6.0 years. The SMI was significantly related to handgrip strength (partial correlation coefficient = 0.293, P = 0.016) but not to gait speed (partial correlation coefficient = - 0.183, P = 0.138). Similarly, the SMI of the ECW/TBW < 0.40 group was significantly related to handgrip strength (partial correlation coefficient = 0.372, P = 0.009) but not gait speed (partial correlation coefficient = - 0.267, P = 0.066); however, the SMI of the ECW/TBW ≥ 0.40 group was not related to either variable. CONCLUSION: ECW/TBW represents a confounding factor, which should be considered when using BIA for sarcopenia diagnosis.

Association of muscle mass and quality with hand grip strength in elderly patients with heart failure.

In patients with heart failure, it is unknown whether the extracellular water (ECW)/intracellular water (ICW) ratio is associated with muscle strength, and thus, it is not well understood whether poor muscle quality contributes to muscular weakness. This study examined the relationship among hand grip strength, skeletal muscle mass index (SMI), and upper limb ECW/ICW ratio in patients with heart failure. This study followed a cross-sectional design. Demographic data, medical information, and hand grip strength were collected. The SMI and ECW/ICW ratio were measured using bio-impedance analysis (BIA). Hierarchical multiple regression analysis was conducted to identify factors associated with hand grip strength. 51 patients with heart failure were analyzed for this study (mean age 84.58 ± 7.18). Hierarchical multiple regression analysis identified SMI as well as upper limb ECW/ICW ratio as factors associated with hand grip strength, independent of age, sex, body mass index, and Life Space Assessment scores. Standardized partial regression coefficients representing the magnitude of involvement of each independent variable were 0.33 and - 0.16. The coefficient of determination adjusted for degrees of freedom (R2), representing the contribution rate of the regression equation, was 0.830. We revealed that loss of hand grip strength in patients with heart failure is associated with not only with a decrease in skeletal muscle mass, but also with a decline in muscle quality, characterized by an increased upper limb ECW/ICW ratio. BIA is a simple and useful method to measure the ECW/ICW ratio, and in turn, the muscle quality, in patients with heart failure.

Friction dynamics of moisturized human skin under non-linear motion.

OBJECTIVE: Evaluating friction in human skin is important to assess its condition and the effects of skincare cosmetics. In this study, we evaluated the friction dynamics of moisturized skin to show the effects of moisturization on its mechanical properties. METHODS: Friction force was evaluated using a sinusoidal motion friction evaluation system. The skin of the upper arm of 20 subjects was rubbed using a contact probe. The water content of the stratum corneum and the softness of the skin were measured using a Corneometer and a Cutometer, respectively. RESULTS: When human skin was treated with water or 10 wt% glycerol aqueous solution, the friction coefficients increased by 0.23 ± 0.01 and 0.17 ± 0.14, respectively, and the delay times (normalized by calculating the time interval from contact with the probe to the friction response divided by the friction time for one round trip) increased by 0.048 ± 0.034 and 0.055 ± 0.024, respectively. Three different friction profiles were observed: (a) a stable pattern, in which a smooth profile was observed during the sliding process; (b) an oscillation pattern, in which significant oscillation was obtained; and (c) a stick pattern, in which the friction coefficient increased even during the deceleration process. In the case of untreated skin, the oscillation pattern was observed for the majority of subjects. The appearance rate of the stick pattern increased by 80.3% ± 29.4% after treatment with 10 wt% glycerol aqueous solution. These characteristic friction profiles can be explained by a two-step friction model consisting of two modes: (a) friction at the skin surface and (b) the delayed response due to skin deformation. CONCLUSION: Moisturizing the skin with water or 10 wt% glycerol aqueous solution increased the friction coefficient and delay time, dramatically changing the friction profile. These changes were considered to be due to the swelling and softening of the stratum corneum and the increased true contact area between the contact probe and the skin surface.

OBJECTIF: Une évaluation des effets de la friction sur la peau humaine demeure importante dans le but de juger de l'état de la peau ou de l'efficacité des produits cosmétiques pour les soins de la peau. Dans cette étude, nous avons évalué les propriétés d'une peau hydratée soumise à une friction afin d'identifier les effets de l'hydratation sur les propriétés mécaniques de la peau. MÉTHODE: Les forces de friction ont été évaluées grâce à un système d'évaluation du frottement par mouvement sinusoïdal. Une sonde de contact a été utilisée pour frotter la peau sur le haut du bras de 20 participants. La teneur en eau de la couche cornée et la souplesse de la peau ont été mesurées respectivement à l'aide d'un cornéomètre et d'un cutomètre. RÉSULTAT: Le traitement de la peau humaine avec de l'eau ou une solution de glycérol à 10% a entraîné une augmentation du coefficient de friction respectivement de 0.23 ± 0.01 et de 0.17 ± 0.14, ainsi que du délai de réaction (normalisé en divisant l'intervalle de temps entre le contact avec la sonde jusqu'à l'apparition de la réaction à la friction, par le temps de friction pour un aller-retour), de 0.048 ± 0.034 et de 0.055 ± 0.024. Trois profils de friction différents ont également été observés : (1) un modèle stable, (2) un modèle avec une grande oscillation, et (3) un modèle « collé-glissé ¼ où le coefficient de friction augmente même pendant la décélération. Lorsque la peau est sèche, le modèle oscillant a été observé chez la majorité des participants. Le taux d'apparition du modèle « collé-glissé ¼ a augmenté de 80.3 ± 29.4% dans le cas où la peau a été traitée avec une solution de glycérol à 10%. Ces profils caractéristiques de friction ont pu être expliqués à partir d'un modèle de friction composé de deux modes, (a) une friction à la surface de la peau et (b) un délai de réaction dû à la déformation de la peau. CONCLUSION: L'hydratation de la peau avec de l'eau ou une solution de glycérol à 10% a considérablement modifié le profil de friction en raison d'une augmentation du coefficient de friction et du délai de réaction. Nous avons estimé que ces changements sont relatifs au gonflement et à l'assouplissement de la couche cornée, engendrant une augmentation de la surface de contact réel entre la sonde de contact et la surface de la peau.

Total Body and Extracellular Water Measures Are Unrelated to Cramp Sensitivity in Euhydrated Cramp-Prone Individuals.

ABSTRACT: Earp, JE, Stearns, RL, Agostinucci, J, Lepley, AS, and Ward-Ritacco, CL. Total body and extracellular water measures are unrelated to cramp sensitivity in euhydrated cramp-prone individuals. J Strength Cond Res 36(9): 2653-2656, 2022-Spectral bioelectrical impedance analysis (BIA) is a valid and noninvasive tool for measuring total body water (TBW), intracellular water (ICW), and extracellular water (ECW). As altered hydration and electrolyte imbalance have been proposed as one of 2 etiologies for exercise-associated muscle cramps (EAMC), the purpose of this study was to determine if distribution of body water is related to cramp sensitivity in similarly hydrated cramp-prone individuals. To this end, 11 euhydrated subjects who regularly experience EAMC had their relative TBW, ICW, and ECW assessed using 8-pole spectral BIA. Subjects' cramp sensitivity was then assessed by electrically stimulating the tibial nerve at increasing frequencies until a muscle cramp occurred, allowing for the determination of the threshold frequency (TF) at which the cramp occurred. It was observed that TF was not significantly related to TBW ( r = 0.087, p = 0.368), ICW ( r = 0.105, p = 0.338), ECW ( r = 0.087, p = 0.368), or ECW:TBW ( r = 0.147, p = 0.280). As cramp etiology is poorly understood, these results add to a growing body of literature questioning the role of hydration and electrolyte imbalance in EAMC. Although fluid distribution may be unrelated to TF in those who commonly experience EAMC, additional research is needed to compare those who commonly experience cramps (athletes as well as individuals with specific neuropathies or pharmacologically induced cramps) with those who do not experience cramps and to determine if acute shifts in body water compartmentalization are related to changes in cramp sensitivity.

Brain water as a function of age and weight in normal rats.

Rats are frequently used for studying water content of normal and injured brain, as well as changes in response to various osmotherapeutic regimens. Magnetic resonance imaging in humans has shown that brain water content declines with age as a result of progressive myelination and other processes. The purpose of this study was to quantify changes in brain water content during rat development and aging. Brain water content was measured by standard techniques in 129 normal male Sprague-Dawley rats that ranged in age (weight) from 13 to 149 days (18 to 759 g). Overall, the results demonstrated a decrease in water content from 85.59% to 76.56% with increasing age (weight). Nonlinear allometric functions relating brain water to age and weight were determined. These findings provide age-related context for prior rat studies of brain water, emphasize the importance of using similarly aged controls in studies of brain water, and indicate that age-related changes in brain water content are not specific to humans.

Generalized bioelectric impedance-based equations underestimate body fluids in athletes.

The current study aimed: (i) to external validate total body water (TBW) and extracellular water (ECW) derived from athlete and non-athlete predictive equations using radioisotope dilution techniques as a reference criterion in male and female athletes; (ii) in a larger sample, to determine the agreement between specific and generalized equations when estimating body fluids in male and female athletes practicing different sports. A total of 1371 athletes (men: n = 921, age 23.9 ± 1.4 y; women: n = 450, age 27.3 ± 6.8 y) participated in this study. All athletes underwent bioelectrical impedance analyses, while TBW and ECW were assessed with dilution techniques in a subgroup of 185 participants (men: n = 132, age 21.7 ± 5.1 y; women: n = 53, age 20.3 ± 4.5 y). Two specific and eight generalized predictive equations were tested. Compared to the criterion methods, no mean bias was observed using the athlete-specific equations for TBW and ECW (-0.32 to 0.05, p > 0.05) and the coefficient of determination ranged from R2  = 0.83 to 0.94. The majority of the generalized predictive equations underestimated TBW and ECW (p < 0.05); R2 ranged from 0.66 to 0.89. In the larger sample, all the generalized equations showed lower TBW and ECW values (ranging from -6.58 to -0.19, p < 0.05) than specific predictive equations; except for TBW in female power/velocity (one equation) athletes and team sport (two equations). The use of generalized BIA-based equations leads to an underestimation of TBW, and ECW compared to athlete-specific predictive equations. Additionally, the larger sample indicates that generalized equations overall provided lower TBW and ECW compared to the athlete-specific equations.

Impact of Follicular Menstrual Phase on Body Composition Measures and Resting Metabolism.

PURPOSE: This study aimed to identify the effects of early follicular (EF) and midfollicular (MF) menstrual phases on body composition, resting metabolic rate (RMR), and respiratory quotient (RQ) assessment accuracy to identify an optimal testing period. METHODS: Body composition was obtained from a four-compartment (4C) criterion model (fat mass (FM), fat-free mass, body fat percent, and dual-energy x-ray absorptiometry (DXA; FM, lean mass (LM), trunk FM, and trunk LM) in 19 eumenorrheic females (mean ± SD: age, 21.3 ± 3.1 yr, body mass index, 23.6 ± 1.8 kg·m-2). RMR (kcal·d-1) and RQ (a.u.) were measured via indirect calorimetry for 25 min. Body composition, RMR, and RQ were measured during the EF and MF phases. Dependent-samples t-tests were used to compare outcomes between EF and MF. RESULTS: 4C outcomes were similar between phases (P > 0.05). During EF, the following 4C components were significantly greater (P < 0.05): body volume (mean difference (MD) ± SD, 0.70 ± 1.05 L), extracellular fluid (MD ± SD, 0.27 ± 0.51 L), and body mass (MD ± SD, 0.56 ± 0.80 kg). DXA-measured LM, body fat percent, trunk LM, and trunk FM were similar (P > 0.05); however, DXA FM was significantly greater during EF (MD ± SD, 0.29 ± 0.40 kg; P = 0.005), yet within measurement error of the device. Although RMR was not significantly different between phases (MD ± SD, 6.0 ± 190.93 kcal·d-1; P > 0.05), RQ was significantly higher during EF (mean ± SD, 0.03 ± 0.06 a.u.; P = 0.029) compared with MF. CONCLUSIONS: Body composition from 4C and DXA do not seem to be affected beyond measurement error as a result of compartmental changes from the menstrual cycle. During MF, women oxidized more fat as demonstrated by a lower RQ. Researchers should aim to be more inclusive and schedule testing for females within 11-12 d from the onset of menstruation.

Extracellular water/total body water ratio as predictor of mortality in hemodialysis patients.

BACKGROUND: Overhydration is a predictor of mortality in hemodialysis (HD) patients. Bioimpedance spectroscopy (BIS) is used to determine the body composition. Extracellular Water/Total Body Water (ECW/TBW) ratio has been proposed to predict mortality. METHODS: Multicenter, prospective, observational, proof-of-concept study to estimate the impact of ECW/TBW in global and cardiovascular mortality and the relationship with cardiovascular biomarkers. The study included 60 patients (mean age, 71.8 ± 11.4 years; mean time on HD, 52.3 ± 30.8 months) with a median follow-up of 30.5 months (IQ range, 17.2-34 months). RESULTS: Post-dialysis ECW/TBW was directly associated with NT-proBNP and cTnT. During the study 28 patients died, most of them (43%) due to cardiovascular events. Compared to the survivors, these subjects had a higher post-dialysis ECW/TBW ratio (p = 0.006), while for cardiovascular mortality the only significant difference was a higher pre-dialysis ECW/TBW. The ability of post-dialysis ECW/TBW ratio to predict all-cause mortality had an area under the ROC curve (AUC) of 0.71 (CI 95%, 0.57-0.81; p = 0.002), with a cutoff point of 0.5023. For cardiovascular mortality the AUC was 0.66 (CI 95%, 0.52-0.77; p = 0.045), with a cutoff point of 0.4713. CONCLUSIONS: The post-dialysis ECW/TBW ratio measured by BIS can be a predictor of all-cause and cardiovascular mortality.

Total body water in full-term and preterm newborns: systematic review and meta-analysis.

BACKGROUND: Total body water (TBW) is one component of fat-free mass and changes in TBW are influenced by fluid shifts (especially during transition to postnatal life), electrolyte balance and nutritional status. Normal values for term-born neonates and preterm infants at birth have not been defined in large cohorts, limiting investigation into its monitoring and use in clinical practice. OBJECTIVE: To systematically review the evidence base for percentage of TBW in term-born infants, quantify the effect of prematurity on TBW at birth, and describe normal progression of TBW over time in preterm infants. METHODS: Systematic review of Medline, Web of Science Core Collection and EBSCO-CINAHL (January 1946 to January 2020). Included articles used dilutional methods to assess TBW. RESULTS: Searches identified 2349 articles of which 22 included data suitable for analysis. Mean TBW in term-born newborns was 73.8% (95% CI 72.47% to 75.06%, 15 studies, 433 infants). Meta-regression showed that TBW was higher in preterm infants (up to 90% at 26 weeks gestation, dropping to 75% at 36 weeks corrected gestation) and was negatively correlated with gestation at birth, falling 1.44% per week (95% CI 0.63% to 2.24%, 9 studies, 179 infants). Analysis of TBW over time during the ex utero growth of preterm infants was not possible due to paucity of data. CONCLUSION: This review defines the normal TBW percentage in term-born infants and confirms and quantifies previous findings that preterm infants have a higher TBW percentage.

Effects of Water Restriction and Water Replenishment on the Content of Body Water with Bioelectrical Impedance among Young Adults in Baoding, China: A Randomized Controlled Trial (RCT).

Insufficient water intake may affect body composition. The purpose of this research was to explore the effects of water restriction and replenishment on body composition and to evaluate the optimum amount of water that improves body composition. A total of 76 young adults aged 18-23 years old (40 males and 36 females) in Baoding, China, were recruited in this randomized controlled trial, with a 100% completion rate. After fasting overnight for 12 h, at 8:00 a.m. of day 2, a baseline test, including anthropometric indices and collection of urine and blood samples, was explored. Participants were then subjected to water restriction for 24 h, and three meals with ≤75% water content were provided. At 8:00 AM of day 3, the same indices were determined as a dehydration test. Then, participants were randomly assigned into four groups: three water replenishment groups (WR groups 1, 2, and 3 given 1000, 500, and 200 mL of purified water, respectively) and one non-replenishment group (NR group, with no water). After 90 min, the same measurements were performed as a rehydration test. Compared with the baseline test, during the dehydration test, the intracellular water to total body water ratio (ICW/TBW) increased; and extracellular water (ECW), ECW/TBW (extracellular water to total body water ratio), and TBW decreased (all p < 0.05). For males, significant differences were found in ECW, ECW/ICW (extracellular water to intracellular water ratio), ICW/TBW, and ECW/TBW (all p < 0.05); for females, significant reductions were found in ICW, ECW, TBW, ECW/ICW, ICW/TBW, and ECW/TBW (all p < 0.05). Furthermore, significant differences were found in ICW, ECW, ICW/TBW, ECW/TBW, ECW/ICW, TBW, and TBW/BW between males and females during the baseline and dehydration test (all p < 0.05). Comparing the dehydration test with the rehydration test, there were significant interactions between time × volume in ICW and TBW (F = 3.002, p = 0.036; F = 2.907, p = 0.040); in males, these were only found in ICW (F = 3.061, p = 0.040); in females, they were found in ICW and TBW (F = 3.002, p = 0.036; F = 2.907, p = 0.040). The ICW levels in WR groups 1 and 2 were all higher than in the NR group (all p < 0.05); the TBW was higher in WR group 1 than in the NR group (p < 0.05). No significant differences were found between WR groups 1 and 2, either in males or in females (all p > 0.05). In the rehydration test, significant differences in body composition were found between males and females among the four groups (all p < 0.05). Water restriction had adverse effects on body composition, and females were more susceptible to water restriction than males. Water replenishment improved the water content of body composition, alleviating the adverse effects of water restriction on ICW and TBW. After water restriction for 36 h, the optimum volume of water to improve body composition among young male adults was 1000 mL, but this was not the case for females.

Feeding Your Himalayan Expedition: Nutritional Signatures and Body Composition Adaptations of Trekkers and Porters.

High-altitude exposure leads to many physiological challenges, such as weight loss and dehydration. However, little attention has been posed to the role of nutrition and ethnic differences. Aiming to fulfill this gap, five Italian trekkers and seven Nepalese porters, all males, recorded their diet in diaries during a Himalayan expedition (19 days), and the average daily intake of micro and macro-nutrients were calculated. Bioimpedance analysis was performed five times during the trek; muscle ultrasound was performed before and after the expedition, only for the Italians. The Nepalese group consumed a lot of rice and only Italians consumed cheese. Water intake was slightly over 3000 g/d for both groups. Nepalese diet had a higher density of dietary fibre and lower density of riboflavin, vitamins A, K, and B12. Intake of calcium was lower than recommended levels. Body mass index, waist circumference, fat-free mass, and total body water decreased in both groups, whereas resistance (Rz) increased. Italians reactance (Xc) increased at day 9, whereas that of Nepalese occurred at days 5, 9, and 16. The cross-sectional area of the Vastus lateralis was reduced after the expedition. Specific nutritional and food-related risk factors guidance is needed for diverse expedition groups. Loss of muscle mass and balance of fluids both deserve a particular focus as concerns altitude expeditions.

Evaluación de la composicion corporal antes y después de la reducción de peso con baipás gastrico en Y de Roux. ¿Son confiables las mediciones de la bioimpedanciometría? / Body composition assessment before and after weight loss following a Roux-en-Y gastric bypass. Are bioimpedanciometry estimations reliable?

INTRODUCCIÓN: en pacientes con obesidad severa y mórbida se ha observado que la evaluación por bioimpedanciometría (BIA) genera una subestimación de la masa grasa (MG) y del peso perdido como MG después de la cirugía bariátrica, sobreestimándose la pérdida de masa libre de grasa (MLG) y la masa muscular. OBJETIVO: evaluar la confiabilidad de la BIA para estimar el agua corporal total (ACT), la MLG, la MG y sus cambios después de 6 meses de un baipás gástrico en Y de Roux (BPGYR) en pacientes con obesidad severa y mórbida. MÉTODOS: 36 adultos con indicación de BPGYR se estudiaron prospectivamente. Se midió el ACT por deuterio (D) y se calcularon la MLG y MG. Con BIA de doble frecuencia (5 y 200 kHz) (Bodystat Dualscan(R)) se estimaron la MG, la MLG, el ACT, el agua extracelular (AEC), el agua intracelular (AIC) y la relación AEC/AIC. RESULTADOS: antes del BPGYR, la BIA sobreestimó el ACT en 2,6 ± 4,3 L (p = 0,002) y la MLG en 3,5 ± 5,7 kg (p = 0,002), y subestimó el %MG en 2,98 ± 4,7% (p = 0,002). La relación AEC/AIC mostró una correlación positiva con la sobreestimación de la MLG por BIA (r = 0,49; p = 0,002). Después de la cirugía, las diferencias entre BIA y D no fueron significativas y el error de estimación de la MLG no se correlacionó con la relación AEC/AIC. CONCLUSIONES: la BIA genera una subestimación de la MG como la reportada, la cual se atenúa después de la reducción de peso, subestimando el peso perdido como MG y sobreestimando la pérdida de MLG. Futuras investigaciones podrán evaluar si estos errores se reproducen con otros equipos de BIA

INTRODUCTION: in patients with severe and morbid obesity it has been observed that bioimpedance (BIA) assessment generates an underestimation of fat mass (FM) and weight loss as FM after bariatric surgery, overestimating the loss of fat-free mass (FFM) and muscle mass. OBJECTIVE: to evaluate the reliability of bioelectrical impedance analysis (BIA) to estimate total body water (TBW), fat-free mass (FFM), fat mass (FM), and its changes after 6 months of a Roux-en-Y gastric bypass (RYGBP), in patients with severe and morbid obesity. METHODS: thirty-six patients approved for RYGBP were prospectively studied. TBW was measured by deuterium (D), and FM and FFM were calculated. A dual-frequency BIA device (5 and 200 kHz) (Bodystat Dualscan(R)) was used to estimate FM, FFM, TBW, extracellular water (ECW), intracellular water (ICW), and ECW/ICW ratio. RESULTS: before RYGBP, BIA overestimated TBW by 2.6 ± 4.3 L (p = 0.002) and FFM by 3.5 ± 5.7 kg (p = 0.002), and underestimated FM% by 2.98 ± 4.7% (p = 0.002). The ECW/ICW ratio showed a significant and positive correlation with the difference BIA-D for FFM (r = 0.49; p = 0.002). After surgery, the differences between BIA and D were not significant, and the estimation error of FFM did not correlate with the ECW/ICW ratio. CONCLUSIONS: BIA generates an underestimation of FM as reported in patients with severe and morbid obesity, which is attenuated after weight reduction, underestimating weight loss as FM and overestimating FFM loss. Future research may assess whether these errors are reproduced by other BIA devices

Francis Moore y la composición corporal / Francis Moore and body composition

Una de las líneas de investigación más potentes en el Departamento de Cirugía de la Universidad de Harvard bajo la dirección de Francis Moore fue el estudio de la composición corporal. Hasta los años 40 del siglo pasado no se sabía la cantidad de líquidos en el ámbito corporal ni en los distintos compartimentos, No podía valorarse el significado de las pérdidas de sodio, agua o potasio sin saber los valores basales. Importante era saber también la traslocación de líquidos y solutos en el curso de las enfermedades graves. Los trabajos de Moore sobre composición corporal condujeron a una definición de la bioquímica de la enfermedad quirúrgica y a un conocimiento de los requerimientos de los pacientes graves o traumatizados que ha beneficiado a cirujanos, cardiólogos, internistas, pediatras, nutricionistas, y veterinarios. El conocimiento de la composición corporal ha hecho que la cirugía se desarrolle enormemente en un marco de mayor seguridad

One of the most important lines of investigation in the Department of Surgery of Harvard University under the direction of Francis Moore was body composition. The amount of liquids in different body compartments was unknown until the forties of last century. Sodium, potassium or water losses could not be evaluated without knowing basal values. It was also important to know liquids' and solutes' translocation in the course of severe diseases. Moore contributions about body composition contributed to a biochemical definition of surgical disease and to knowing the requirements of severe diseases or trauma patients. This knowledge has benefited surgeons, cardiologists, pediatricians, nutritionists and veterinarians. The knowledge of body composition has conducted surgery to be performed in a frame of more safety

Reviewing the current methods of assessing hydration in athletes.

BACKGROUND: Despite a substantial body of research, no clear best practice guidelines exist for the assessment of hydration in athletes. Body water is stored in and shifted between different sites throughout the body complicating hydration assessment. This review seeks to highlight the unique strengths and limitations of various hydration assessment methods described in the literature as well as providing best practice guidelines. MAIN BODY: There is a plethora of methods that range in validity and reliability, including complicated and invasive methods (i.e. neutron activation analysis and stable isotope dilution), to moderately invasive blood, urine and salivary variables, progressing to non-invasive metrics such as tear osmolality, body mass, bioimpedance analysis, and sensation of thirst. Any single assessment of hydration status is problematic. Instead, the recommended approach is to use a combination, which have complementary strengths, which increase accuracy and validity. If methods such as salivary variables, urine colour, vital signs and sensation of thirst are utilised in isolation, great care must be taken due to their lack of sensitivity, reliability and/or accuracy. Detailed assessments such as neutron activation and stable isotope dilution analysis are highly accurate but expensive, with significant time delays due to data analysis providing little potential for immediate action. While alternative variables such as hormonal and electrolyte concentration, bioimpedance and tear osmolality require further research to determine their validity and reliability before inclusion into any test battery. CONCLUSION: To improve best practice additional comprehensive research is required to further the scientific understanding of evaluating hydration status.

Approach to Electrolyte Abnormalities, Prerenal Azotemia, and Fluid Balance.

Volume and electrolyte evaluation and management is seen frequently in primary care practices. Some of the most common abnormalities encountered in outpatient practices are prerenal azotemia, dysnatremias, and altered potassium levels. Perturbations in volume or electrolyte concentrations can lead to serious organ dysfunction as well as hemodynamic collapse. This review focuses on the maintenance and regulation of intravascular volume and electrolytes, specifically sodium and potassium.

Importancia del consumo de agua en la salud y la prevención de la enfermedad: situación actual / The importance of water consumption in health and disease prevention: the current situation

Aunque el agua es un nutriente esencial para la vida y el componente más abundante de nuestro cuerpo, recibe escasa atención en las recomendaciones dietéticas y las guías clínicas. Existen inconvenientes para determinar las cifras óptimas, tanto para la cantidad de agua que debe contener el cuerpo como para su ingesta. La ingesta y eliminación del agua dependen de factores no constantes y difíciles de medir, a su vez compensados por la capacidad del organismo para la homeostasis. Dada la falta de evidencia científica para el establecimiento de recomendaciones, se han estimado las "ingestas adecuadas" (para mantener un estado de hidratación adecuado) utilizando datos de ingestas de agua en grupos de personas sanas. La Autoridad Europea de Seguridad Alimentaria (EFSA) también considera la osmolaridad deseable en la orina para estimar la ingesta adecuada de agua en los adultos. Los estudios clínicos han mostrado en general beneficios con una hidratación adecuada y perjuicios con sus desequilibrios, ya sean cuantitativos (deshidratación y sobrehidratación) o cualitativos (agua extracelular e intracelular). Desafortunadamente, estos estudios son escasos y suelen tener diseños deficientes, ya sean transversales, de casos y controles o prospectivos, utilizando muestras pequeñas o métodos indirectos para evaluar el estado de hidratación. En este artículo se presenta información de actualización respecto a: 1) la adherencia a las recomendaciones de consumo de agua y sugerencias para mejorarla; 2) técnicas disponibles para medir el estado de hidratación y sus aplicaciones clínicas; 3) efectos de la hidratación/deshidratación en las actividades físicas o cognitivas y en las enfermedades crónicas; y 4) normativa española sobre calidad y salubridad del agua

Water is an essential nutrient for life and the most abundant component in the human body. However, its dietary recommendations or clinical management guidelines do not receive as much attention as they deserve. In addition, there are some obstacles to establishing optimal values, both for the amount of water the body must contain and for water ingestion. Water intake and elimination depend on unsteady factors that are difficult to measure and, at the same time, compensated by the body's ability to regulate homeostasis. Since scientific evidence is lacking for establishing recommendations, "adequate intakes" (to maintain an adequate hydration state) have been estimated using data on water intake from groups of healthy people. The European Food Safety Authority (EFSA) also considers desirable the use of urine osmolarity to estimate the adequacy of water intake in adults. Clinical studies have generally shown the benefits of adequate hydration and the damage caused by water imbalance, whether quantitative (dehydration and overhydration) or qualitative (extracellular and intracellular water). Unfortunately, these studies are few and often have poor cross-sectional, case-control, or prospective designs, and use small samples or indirect methods to assess hydration status. This article presents up-to-date information on subjects such as: 1) compliance with water consumption recommendations and suggestions for improvement; 2) techniques available to measure hydration status and their clinical applications; 3) effects of hydration/dehydration on physical or cognitive activities and chronic diseases; and 4) existing Spanish regulations on the quality and salubrity of water