High-standard predictive equations for estimating body composition using bioelectrical impedance analysis: a systematic review.

The appropriate use of predictive equations in estimating body composition through bioelectrical impedance analysis (BIA) depends on the device used and the subject's age, geographical ancestry, healthy status, physical activity level and sex. However, the presence of many isolated predictive equations in the literature makes the correct choice challenging, since the user may not distinguish its appropriateness. Therefore, the present systematic review aimed to classify each predictive equation in accordance with the independent parameters used. Sixty-four studies published between 1988 and 2023 were identified through a systematic search of international electronic databases. We included studies providing predictive equations derived from criterion methods, such as multi-compartment models for fat, fat-free and lean soft mass, dilution techniques for total-body water and extracellular water, total-body potassium for body cell mass, and magnetic resonance imaging or computerized tomography for skeletal muscle mass. The studies were excluded if non-criterion methods were employed or if the developed predictive equations involved mixed populations without specific codes or variables in the regression model. A total of 106 predictive equations were retrieved; 86 predictive equations were based on foot-to-hand and 20 on segmental technology, with no equations used the hand-to-hand and leg-to-leg. Classifying the subject's characteristics, 19 were for underaged, 26 for adults, 19 for athletes, 26 for elderly and 16 for individuals with diseases, encompassing both sexes. Practitioners now have an updated list of predictive equations for assessing body composition using BIA. Researchers are encouraged to generate novel predictive equations for scenarios not covered by the current literature.Registration code in PROSPERO: CRD42023467894.

H2OAthletes study protocol: effects of hydration changes on neuromuscular function in athletes.

We aim to understand the effects of hydration changes on athletes' neuromuscular performance, on body water compartments, fat-free mass hydration and hydration biomarkers and to test the effects of the intervention on the response of acute dehydration in the hydration indexes. The H2OAthletes study (clinicaltrials.gov ID: NCT05380089) is a randomised controlled trial in thirty-eight national/international athletes of both sexes with low total water intake (WI) (i.e. < 35·0 ml/kg/d). In the intervention, participants will be randomly assigned to the control (CG, n 19) or experimental group (EG, n 19). During the 4-day intervention, WI will be maintained in the CG and increased in the EG (i.e. > 45·0 ml/kg/d). Exercise-induced dehydration protocols with thermal stress will be performed before and after the intervention. Neuromuscular performance (knee extension/flexion with electromyography and handgrip), hydration indexes (serum, urine and saliva osmolality), body water compartments and water flux (dilution techniques, body composition (four-compartment model) and biochemical parameters (vasopressin and Na) will be evaluated. This trial will provide novel evidence about the effects of hydration changes on neuromuscular function and hydration status in athletes with low WI, providing useful information for athletes and sports-related professionals aiming to improve athletic performance.

Athletic bioimpedance-based equations underestimate fat free mass components in male elite soccer players: development and validation of new soccer-specific predictive models.

BACKGROUND: Bioelectrical impedance analysis (BIA) is a rapid and user-friendly technique for assessing body composition in sports. Currently, no sport-specific predictive equations are available, and the utilization of generalized formulas can introduce systematic bias. The objectives of this study were as follows: (i) to develop and validate new predictive models for estimating fat-free mass (FFM) components in male elite soccer players; (ii) to evaluate the accuracy of existing predictive equations. METHODS: A total of 102 male elite soccer players (mean age 24.7 ± 5.7 years), participating in the Italian first league, underwent assessments during the first half of the in-season period and were randomly divided into development and validation groups. Bioelectrical resistance (R) and reactance (Xc), representing the bioimpedance components, were measured using a foot-to-hand BIA device at a single frequency of 50 kHz. Dual-energy X-ray absorptiometry was employed to acquire reference data for FFM, lean soft tissue (LST), and appendicular lean soft tissue (ALST). The validation of the newly developed predictive equations was conducted through regression analysis, Bland-Altman tests, and the area under the curves (AUC) of regression receiver operating characteristic (RROC) curves. RESULTS: Developed models were: FFM = - 7.729 + (body mass × 0.686) + (stature2/R × 0.227) + (Xc × 0.086) + (age × 0.058), R2 = 0.97, Standard error of estimation (SEE) = 1.0 kg; LST = - 8.929 + (body mass × 0.635) + (stature2/R × 0.244) + (Xc × 0.093) + (age × 0.048), R2 = 0.96, SEE = 0.9 kg; ALST = - 24.068 + (body mass × 0.347) + (stature2/R × 0.308) + (Xc × 0.152), R2 = 0.88, SEE = 1.4 kg. Train-test validation, performed on the validation group, revealed that generalized formulas for athletes underestimated all the predicted FFM components (p < 0.01), while the new predictive models showed no mean bias (p > 0.05), with R2 values ranging from 0.83 to 0.91, and no trend (p > 0.05). The AUC scores of the RROC curves indicated an accuracy of 0.92, 0.92, and 0.74 for FFM, LST, and ALST, respectively. CONCLUSIONS: The utilization of generalized predictive equations leads to an underestimation of FFM and ALST in elite soccer players. The newly developed soccer-specific formulas enable valid estimations of body composition while preserving the portability of a field-based method.

Effect of resistance training on bioelectrical phase angle in older adults: a systematic review with Meta-analysis of randomized controlled trials.

Resistance training has been proposed as a valid practice to counteract the aging effect on body mass and its components, which can be easily evaluated though the bioelectrical impedance analysis. This study aimed to achieve a systematic review with meta-analysis on the impact of resistance training on bioelectrical proprieties in older adults.A literature review was done in four electronic databases up to 1 January 2022. The inclusion criteria were: (i) participants aged ≥ 60 years; (ii) resistance training lasted ≥ 8 weeks; (iii) measurement of raw bioelectrical parameters in randomized controlled study designs.The outcomes of the trial had to be bioelectrical phase angle (PhA), resistance (R), and reactance (Xc). The methodological quality was assessed using the Rosendal scale.Overall, seven studies with a total of 344 participants were eligible for the analysis. The quality assessment yielded a score of 71.3%. Bioelectrical PhA (0.52 degree [95%CI 0.32, 0.71], p < 0.001) and Xc (3.58 ohms [95%CI 1.97, 5.19], p < 0.001) increased, whereas R decreased (-28.50 ohms [95%CI -41.39, -15.60], p < 0.001) after the resistance training programs.In this meta-analysis, resistance training promoted increases of PhA, which result from an increase in Xc concomitant with a reduction in R. According to the bioimpedance vector analysis, resistance-trained people experienced a beneficial leftward vector displacement, whilst inactivity induced a rightward vector displacement within the R-Xc graph. In future, more sophisticated and rigorous studies that address specific criteria, methods and targeted designs are required to identify which equipment and protocols allow for an optimization of the resistance training effects.Registration code in PROSPERO: CRD42020168057.

Prediction of body water compartments by raw bioelectrical impedance parameters in athletes: Comparison between series and parallel measurements.

BACKGROUND: The aim of this study was to determine the predictive role of series and parallel bioelectrical impedance-derived parameters in predicting total body (TBW), intracellular (ICW), and extracellular water (ECW) in athletes. METHODS: This cross-sectional study analyzed 134 male (21.33 ± 5.11 years) and 64 female (20.45 ± 5.46 years) athletes. Using dilution techniques, TBW and ECW were determined while ICW was the difference between both. Raw and standardized for height (/H) bioelectrical resistance (R), reactance (Xc), and impedance (Z) values were obtained using a phase-sensitive device at a single frequency in a series array (s). These were mathematically transformed in a parallel array (p) and capacitance (CAP). Fat-free mass (FFM) was assessed by dual-energy X-ray absorptiometry. RESULTS: Multiple regressions adjusted for age and FFM show that R/Hs, Z/Hs, R/Hp, and Z/Hp were significant predictors of TBW (p < 0.001 in females and males). While Xc/Hs did not predict ICW, Xc/Hp was a predictor (p < 0.001 in females and Males). In females, R/H and Z/H predicted similarly TBW, ICW, and ECW. In males, R/Hs was considered a better predictor than R/Hp for TBW and ICW, and the Xc/Hp was considered the best predictor for ICW. Another significant predictor of ICW was CAP (p < 0.001 in females and males). CONCLUSION: This study highlights the potential value of parallel bioelectrical impedance values to identify fluid compartments in athletes as an alternative to the regularly used series measurements. Moreover, this study supports Xc in parallel, and ultimately CAP, as valid indicators of cell volume.

Bioelectrical impedance analysis versus reference methods in the assessment of body composition in athletes.

The present systematic review aimed to compare the accuracy of Bioelectrical Impedance Analysis (BIA) and Bioelectrical Impedance Vector Analysis (BIVA) vs. reference methods for the assessment of body composition in athletes. Studies were identified based on a systematic search of internationally electronic databases (PubMed and Scopus) and hand searching of the reference lists of the included studies. In total, 42 studies published between 1988 and 2021 were included. The methodological quality was assessed using the Quality Assessment Tool for Observational Cohort and Cross-sectional Studies as recommended by the National Institute of Health. Twenty-three studies had an overall good rating in terms of quality, while 13 were rated as fair and 6 as poor, resulting in a low to moderate risk of bias. Fat mass was inconsistently determined using BIA vs. the reference methods, regardless of the BIA-technology. When using the foot to hand technology with predictive equations for athletes, a good agreement between BIA and the reference methods was observed for fat-free mass, total body, intra and extra cellular water. However, an underestimation in fat-free mass and body fluids was found when using generalized predictive equations. Classic and Specific BIVA represented a valid approach for assessing body fluids (Classic BIVA) and percentage of fat mass (Specific BIVA). The present systematic review suggests that BIA and BIVA can be used for assessing body composition in athletes, provided that foot-to-hand technology, predictive equations, and BIVA references for athletes are used.

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.

Body image perception and body composition in early adolescents: a longitudinal study of an Italian cohort.

BACKGROUND: Adolescence is a sensitive period of life in which everyone faces physical and psychological changes. No longitudinal studies considering changes in body image perception and body composition in Italian adolescents have been carried out. The aims of this study were to evaluate the longitudinal change in body composition and weight status in a sample of Italian students of both sexes over the 3 years of middle school and to analyse the influence of these parameters on the perception and satisfaction of one's own body image. METHODS: Sixty-four males and seventy females were followed longitudinally from 11 to 14. Age at first measurement was 11.8 ± 0.3 yrs. in males and 11.9 ± 0.3 yrs. in females, then the students were measured again after 1 year and 2 years. Anthropometric measurements were collected and body composition was assessed by skinfolds. Maturity status was detected by age at menarche in females and by estimated age at peak height velocity in males; sports practice was assessed by a questionnaire. Body Silhouette Charts were used to assess body image perception. The degree of body image dissatisfaction and improper perception of weight status were evaluated. Univariate and multivariate analyses were applied. RESULTS: Height, sitting height, leg length, and weight increments were higher in males than in females, and in both sexes the sitting height increment was higher than that of leg length. Skinfold thicknesses and percentage of body fat, showed a decrease in males and an increase in females over the 3 years. About 90% of the sample practiced sport during the 3 years. No significant variations in body image perception were observed among repeated measures but significantly differences were observed between sexes. Although the girls showed a lower incidence of overweight and obesity than boys, girls had a higher dissatisfaction than males. Males were less accurate in one's perception of one's own weight status. CONCLUSIONS: The changes in body composition observed in the sample of the present study were in accordance with their maturity stage. An increase in parameters connected with adiposity is observed in females and a decrease in males. Body image perception did not seem to change with growth, but associations were found between body image perception and BMI and sex. Monitoring body image perception in young adolescents, especially in females and in overweight/obese subjects, is a priority to prevent nutritional disorders.

Fat-free Mass Bioelectrical Impedance Analysis Predictive Equation for Athletes using a 4-Compartment Model.

Bioelectrical impedance analysis equations for fat-free mass prediction in healthy populations exist, nevertheless none accounts for the inter-athlete differences of the chemical composition of the fat-free mass. We aimed to develop a bioimpedance-based model for fat-free mass prediction based on the four-compartment model in a sample of national level athletes; and to cross-validate the new models in a separate cohort of athletes using a 4-compartment model as a criterion. There were 142 highly trained athletes (22.9±5.0 years) evaluated during their respective competitive seasons. Athletes were randomly split into development (n=95) and validation groups (n=47). The criterion method for fat-free mass was the 4-compartment model. Resistance and reactance were obtained with a phase-sensitive 50 kHz bioimpedance device. Athletic impedance-based models were developed (fat-free mass=- 2.261+0.327*Stature2/Resistance+0.525*Weight+5.462*Sex, where stature is in cm, Resistance is in Ω, Weight is in kg, and sex is 0 if female or 1 if male). Cross validation revealed R2 of 0.94, limits of agreement around 10% variability and no trend, as well as a high concordance correlation coefficient. The new equation can be considered valid thus affording practical means to quantify fat-free mass in elite adult athletes.

Changes in Muscle Contractile Properties after Cold- or Warm-Water Immersion Using Tensiomyography: A Cross-Over Randomised Trial.

Muscle contractile properties in clinical practice are often measured using either subjective scales or high-cost, inaccessible equipment. In this randomised cross-over study, we aimed to explore the use of tensiomyography (TMG) to assess changes in muscle contractile properties after cold- and warm-water immersion. The muscle contractile properties of the biceps femoris (BF) were assessed using TMG in 12 healthy active men (mean age 23 ± 3 years, Body Mass Index 22.9 ± 1.3 kg/m2) before and after a 20-min warm- or cold-water immersion over a period of 40 min. Muscle displacement (Dm) and contraction time (Tc) were registered as the main variables of the study. There was a significant condition by time interaction for Dm (p < 0.01). Post hoc analysis showed that, compared to the baseline, there was an increase in Dm 40 min after warm-water immersion (p < 0.01) and a decrease at 10 min after cold-water immersion (p < 0.01). No significant effect was found for Tc. Our results indicate that muscle contractile properties are affected by water temperature and time after the immersion; therefore, these factors should be taken into account when water-immersion is used as a recovery strategy.

Height prediction in elite Italian rugby players: A prospective study.

OBJECTIVES: We investigated the validity of the Mirwald equation as an estimate of height in a cohort of rugby players. METHODS: This was a prospective study with agreement analysis of height assessments conducted in 39 male youth rugby players (mean age 15.1 ± 0.9 years). During the 2007/2008 season, 151 young athletes were selected by rugby coaches using subjective decisions based on current performance and future potential. The rugby players were measured by physician experts and their height was estimated using the Mirwald formula (MF). Only 39 athletes were finally selected because they reached an elite level, allowing actual adult height to be collected from the official team websites in June 2018. Method agreement was assessed by intraclass correlation coefficient, regression, and plotted by Bland and Altman analysis. RESULTS: Twenty athletes played in the Italian National team and 19 in the First Italian Division (Eccellenza). Overall, they presented an early maturation and the MF was able to accurately estimate height. The MF underestimated height (187.4-189.1 cm) and showed a high association with actual adult players' height (r = 0.925, P < .001). CONCLUSIONS: Our results demonstrate that the MF, whose estimation of stature is based on height, sitting height, body mass, and leg length is able to predict stature in rugby players.

Anthropometry, Physical and Movement Features, and Repeated-sprint Ability in Soccer Players.

This study aimed to evaluate the associations of anthropometry, functional movement patterns (FMP) and physical performance characteristics with repeated-sprint ability (RSA) in male youth soccer players. Thirty six athletes (ages 16.6±0.5 years, BMI 22.0±1.3 kg/m2) completed the RSA test and other physical tests including countermovement jump with (CMJA) and without the help of arms (CMJ), 10-m and 20-m straight-line sprints, Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo), and functional movement screen (FMS). In addition, a battery of anthropometric variables was measured. RSA performance components such as best time (BT), mean time (MT) and sprint decrement were calculated. Results showed that measures of physical performance derived from horizontal plane in 10-m and 20-m sprints, were more strongly associated (p<0.01) with RSA performance than those obtained with CMJ or CMJA (p<0.05). High correlations (p<0.01) were found between MT, BT and Yo-Yo distance (r=-0.79, r=-0.67, respectively), as well as with FMS scores (r=-0.68, r=-0.58, respectively). Anthropometric measures, such as fat mass, upper fat area, thigh fat area, calf muscle area, and endomorphy were associated with RSA components (p<0.05). Predictors for the RSA performance identified in the stepwise multivariate analysis included Yo-Yo distance, time in sprints, FMP, and calf muscle area.

Recovery Time Profiling After Short-, Middle- and Long-Distance Swimming Performance.

Piras, A, Cortesi, M, Campa, F, Perazzolo, M, and Gatta, G. Recovery time profiling after short-, middle- and long-distance swimming performance. J Strength Cond Res 33(5): 1408-1415, 2019-We investigated cardiac autonomic responses and hemodynamic parameters on recovery time after short-, middle- and long-swimming performance. Ten male regional-level swimmers were tested to estimate time and frequency domains of arterial baroreflex sensitivity (BRS) and heart rate variability after 100, 200, and 400 m of front crawl. We found a BRS reduction for 90 minutes after a maximal 100- and 200-m front crawl event, meanwhile the reflex was restored back to the baseline value approximately 70 minutes after 400 m. The vagally mediated high-frequency power of R-R intervals was significantly reduced for 30 minutes after 400 m, and more than 90 minutes after 100 and 200 m, with a concomitant increase of sympathetic modulation. After 400 m, athletes have reduced their stroke volume for 50 minutes, which remained at the baseline level after 100 and 200 m. Heart rate was restored back after 90 minutes in all conditions, whereas total peripheral vascular resistance was significantly reduced for 50 minutes after 200 and 400 m, with a persistent reduction after 100 m. Time course of autonomic recovery after 3 different swimming performances is influenced by exercise intensity and duration, showing a rapid recovery after 400 m, an intermediate recovery after 200 m, and a significantly delayed recovery after a more strictly anaerobic performance like 100 m of front crawl. These results could encourage coaches to consider that athlete might be affected by the specific recovery time of the previous exercise performed, suggesting that the management of the exercise intensity, and appropriate monitoring of cardiac autonomic parameters might be helpful to know the physical condition of each athlete.

The Effect of a 20-Week Corrective Exercise Program on Functional Movement Patterns in Youth Elite Male Soccer Players.

CONTEXT: Poor functional movement patterns negatively affect the ability to perform fundamental movements with precision and efficiency, increasing injury risk in athletes. OBJECTIVES: To examine the effect of a 20-week corrective exercise program during the competitive season on functional movement patterns in youth elite male soccer players. DESIGN: Cohort study. SETTING: Team facilities. PARTICIPANTS: Sixty-five youth elite male soccer players (age: 15.89 [0.53] y; weight: 67.42 [6.78] kg; and stature: 175.20 [6.34] cm). Of the 4 teams, 2 were randomly selected to take part in the corrective program. Thus, the players were placed into 2 groups: corrective exercise program and control group. INTERVENTION: Corrective exercise program. MAIN OUTCOME MEASURES: Functional Movement Screen (FMS) was used to assess the presence of dysfunctional, asymmetrical, and painful movements in the players before and after the intervention period. In addition to considering the FMS total score (FMStotal), we separated the screen into 3 parts: FMSmove, FMSflex, and FMSstab. A repeated-measures analysis of variance was conducted to determine the effectiveness of the training program on FMS scores. The chi-square test was performed to determine whether there were significant changes in the frequencies of asymmetric and dysfunctional movements after 20 weeks. RESULTS: No athlete experienced severe injuries during the intervention period. There was a significant group by time interaction (P < .01) for FMStotal, FMSmove, and FMSstab, in which only the corrective exercise program increased their scores after the intervention period (P < .05). A chi-square analysis showed a significant (P < .05) decrease in asymmetric and dysfunctional movements at the follow-up in corrective exercise program, whereas these changes were not observed in the control group. CONCLUSIONS: Youth elite soccer players demonstrate a high prevalence of asymmetric movements during FMS testing, but their functional movement patterns can be improved during the competitive season following a specific corrective exercise program.

Functional Movement Patterns and Body Composition of High-Level Volleyball, Soccer, and Rugby Players.

CONTEXT: Sports practice leads athletes to develop a specific body composition, coordination patterns, and basic motor skills based on the different tactical and physical needs. OBJECTIVES: To present and compare a wide range of functional movement patterns and body composition (BC) parameters of high-level male athletes playing different sports and to determine if there was a relationship between the parameters examined. DESIGN: Cross-sectional study. SETTING: Team facilities. PARTICIPANTS: A total of 30 volleyball, 25 soccer, and 30 rugby players (age = 25.9 [5.0] y and body mass index = 25.6 [4.1] kg/m2). INTERVENTIONS: Functional movement patterns and anthropometric measurements were collected by a physician specifically trained. MAIN OUTCOME MEASURES: Body mass index, fat mass, fat-free mass, upper-arm muscle and fat area, calf muscle and fat area, thigh muscle and fat area, and functional movement screen (FMS) scores. In addition to considering the FMS total score, the authors separated the screen into 3 parts: FMSmove, FMSflex, and FMSstab. RESULTS: The rugby players showed a higher number of asymmetrical and dysfunctional movements than the other athletes (P < .01), while the highest scores in FMSflex were obtained by the volleyball players (P < .01). In addition, most of the asymmetrical and painful movements in the athletes were measured on the shoulder mobility test. Muscle and fat areas differed significantly among the athletes (P < .05). Significant associations were found between movement patterns and several BC variables. In particular, large negative correlations were measured between percentage of fat mass (r = -.616; P < .01), upper-arm fat area (r = -.519; P < .01), and FMS total score. CONCLUSIONS: Functional movement patterns and BC differ in athletes according to the sport practiced. Furthermore, reaching an optimal BC is essential to achieve a satisfactory quality of movement.

Changes in Phase Angle and Handgrip Strength Induced by Suspension Training in Older Women.

This study aimed to present a suspension exercise training program suitable for older adults and to verify the effect of 12 weeks of training on handgrip strength (HS) and anthropometric and bioelectrical impedance parameters in older adults. Thirty older women (age 66.1±4.7 years, BMI 30.6±5.3 kg/m2) were randomly assigned to one of two groups: a training group (TG, n=15) or a control group (CG, n=15). The TG participated in a 12-week suspension training program, while the CG maintained their normal physical activity habits for the duration of the study. Anthropometric, bioelectrical impedance and strength parameters were evaluated before and after the intervention period. There was a significant group by time interaction (p<0.05) for triceps, biceps, subscapular skinfold, percentage of fat mass, phase angle (PhA), resistance, reactance, specific resistance, specific reactance and HS, with significant improvements in the TG after the intervention period (p<0.05) even after adjusting for age and BMI. The results suggest that suspension training promotes increases in PhA and HS in older women.

Anthropometry and Functional Movement Patterns in Elite Male Volleyball Players of Different Competitive Levels.

Toselli, S and Campa, F. Anthropometry and functional movement patterns in elite male volleyball players of different competitive levels. J Strength Cond Res 32(9): 2601-2611, 2018-The aim of this study was to establish specific profiles for anthropometry and functional movement parameters and identify which characteristics can be modified by training to achieve a better quality of movement in elite male volleyball players competing at the Italian National League (Super Lega = 39, aged 25.6 ± 4.7 years and A2 = 30, aged 26.2 ± 5.3 years). Another aim was to value functional movement patterns in relation to morphological traits, with special focus on differences by division and playing positions. Statistical significance was set at p ≤ 0.05. According to discriminant analysis, the differences between players of the 2 Divisions were primarily due to nonmodifiable parameters (humerus width, height, and bicrestiliac width) and modifiable parameters (contracted arm circumference and muscle area of upper arm). Our results highlighted differences according to playing positions. Middle hitters and opposites were taller, heavier and generally showed wide dimensions in contracted arm circumference, upper limb length widths, and handgrip strength than the players of the other roles. Percentage of fat mass was low in players of all roles, such as endomorph somatotype component. Ectomorphic component was maximal in middle hitters, whereas mesomorphic component was maximal in liberos. The players of the 2 Divisions did not show differences in the movement patterns, even if approximately 33% of them showed a dysfunctional movement, with a prevalence of asymmetric movements in the shoulder mobility test. Multiple regression showed that, in volleyball players, an optimal flexibility and mobility was closely related to anthropometric characters with particular emphasis on body fat.

Problems and Opportunities in the use of Bioelectrical Impedance Analysis for Assessing Body Composition During Ketogenic Diets: A Scoping Review.

PURPOSE OF THE REVIEW: The use of bioelectrical impedance analysis (BIA) for monitoring body composition during the ketogenic diet has experienced a rapid surge. This scoping review aimed to assess the validity of procedures applying BIA in the ketogenic diet and to suggest best practices for optimizing its utilization. RECENT FINDINGS: We conducted a systematic scoping review of peer-reviewed literature involving BIA for assessing body composition in individuals adhering to a ketogenic diet. Searches of international databases yielded 1609 unique records, 72 of which met the inclusion criteria and were reviewed. Thirty-five studies used foot-to-hand technology, 34 used standing position technology, while 3 did not declare the technology used. Raw bioelectrical parameters were reported in 21 studies. A total of 196 body mass components were estimated, but predictive equations were reported in only four cases. Most research on BIA during ketogenic diets did not report the equations used for predicting body composition, making it impossible to assess the validity of BIA outputs. Furthermore, the exceedingly low percentage of studies reporting and analyzing raw data makes it challenging to replicate methodologies in future studies, highlighting that BIA is not being utilized to its full potential. There is a need for more precise technology and device characteristics descriptions, full report of raw bioelectrical data, and predictive equations utilized. Moreover, evaluating raw data through vectorial analysis is strongly recommended. Eventually, we suggest best practices to enhance BIA outcomes during ketogenic diets.

ISAK-Based Anthropometric Standards for Elite Male and Female Soccer Players.

This study aimed to provide reference values for anthropometric characteristics of elite male and female soccer players, considering a group of individuals from the general population as controls. The anthropometric profiles of 357 elite soccer players [184 males (age 24.3 ± 4.3 y) and 173 females (age 25.2 ± 5.1 y)] participating in the first Italian league (Serie A) and 363 subjects from the general population [188 males (age 24.2 ± 4.8 y) and 175 females (age 25.0 ± 5.1 y)] were measured according to the guidelines of the International Society for the Advancement of Kinanthropometry (ISAK). Reference percentiles for stature, body mass, circumferences, eight skinfolds (biceps, triceps, subscapular, suprailiac, supraspinal, abdominal, front thigh, and calf), breadths, and somatotype were calculated and stratified by player position and sex. No difference (p > 0.05) was found in age between the two groups. Soccer players showed lower values for the sum of the eight ISAK skinfolds than individuals from the general population of the same sex. This suggests lower adipose tissue, as indicated by a lower endomorphic component. The somatotype was endomorphic mesomorph and mesomorphic endomorph for the male and female individuals from the general population, respectively. The male soccer players were ectomorphic mesomorphs, while the females were balanced mesomorphs, defining a sport-specific morphology. This study provides sex- and role-specific anthropometric standards for elite soccer players. Raw anthropometric reference values may be useful for evaluating body composition without using any predictive equations or assumptions.

Comparison of series and parallel reactance to identify changes in intracellular water in response to physical training in athletes during a sports season.

OBJECTIVE: Cross-sectional evidence has demonstrated that parallel reactance obtained by bioelectrical impedance analysis (BIA) may be an alternative to the regularly used series of measurements to predict intracellular water (ICW) in athletes. However, we are not aware of any studies that have determined the predictive role or compared the effectiveness of both series and parallel reactance for tracking ICW changes during an athletic season. The main aim of this study was to determine the predictive role and compare both series and parallel reactance (Xc) in tracking ICW during an athletic season. RESEARCH METHODS AND PROCEDURES: This longitudinal study analyzed 108 athletes in the preparatory and competitive periods. Using dilution techniques, total body water (TBW) and extracellular water (ECW) were determined and ICW was calculated. Resistance (R), Xc, and impedance (Z) standardized for height were obtained through BIA spectroscopy using a frequency of 50kHz in a series array and then mathematically transformed in a parallel array. RESULTS: Multiple regression analyses showed that only changes in parallel Xc and capacitance (CAP) (P < 0.05) were predictors of delta ICW during the sports season. In contracts, this was not the case for Xcs. Both changes in R and Z, series and parallel, predicted similarly the changes in ECW and TBW (P < 0.05) in athletes. CONCLUSION: Our findings highlight the potential of parallel BIA values to detect changes in body water compartments over a competitive season. These data provide preliminary evidence that changes in parallel Xc/H, and ultimately CAP, represent valid markers of alterations in cell volume during a sports season.