Body composition is acknowledged as a determinant of athletic health and performance. Its assessment is crucial in evaluating the efficiency of a diet or aspects related to the nutritional status of the athlete. Despite the methods traditionally used to assess body composition, bioelectric impedance analysis (BIA) and bioelectric impedance vector analysis (BIVA) have recently gained attention in sports, as well as in a research context. Only until recently have specific regression equations and reference tolerance ellipses for athletes become available, while specific recommendations for measurement procedures still remain scarce. Therefore, the present narrative review summarizes the current literature regarding body composition analysis, with a special focus on BIA and BIVA. The use of specific technologies and sampling frequencies is described, and recommendations for the assessment of body composition in athletes are provided. Additionally, the estimation of body composition parameters (i.e., quantitative analysis) and the interpretation of the raw bioelectrical data (i.e., qualitative analysis) are examined, highlighting the innovations now available in athletes. Lastly, it should be noted that, up until 2020, the use of BIA and BIVA in athletes failed to provide accurate results due to unspecific equations and references; however, new perspectives are now unfolding for researchers and practitioners. In light of this, BIA and especially BIVA can be utilized to monitor the nutritional status and the seasonal changes in body composition in athletes, as well as provide accurate within- and between-athlete comparisons.

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Bioimpedance standards are well established for the normal healthy population and in clinical settings, but they are not available for many sports categories. The aim of this study was to develop reference values for male and female athletes using classic bioimpedance vector analysis (BIVA). In this study, 1556 athletes engaged in different sports were evaluated during their off-season period. A tetrapolar bioelectrical impedance analyzer was used to determine measurements of resistance (R) and reactance (Xc). The classic BIVA procedure, which corrects bioelectrical values for body height, was applied, and fat-free mass, fat mass, and total body water were estimated. In order to verify the need for specific references, classic bioelectrical values were compared to the reference values for the general male and female populations. Additionally, athletes were divided into three groups: endurance, velocity/power, and team sports. In comparison with the general healthy male and female populations, the mean vectors of the athletes showed a shift to the left on the R–Xc graph. Considering the same set of modalities, BIVA confidence graphs showed that male and female endurance athletes presented lower body fluids, fat mass, and fat-free mass than other sets of modalities. This study provides BIVA reference values for an athletic population that can be used as a standard for assessing body composition in male and female athletes.

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.

Purpose: To analyze the association between body fluid changes evaluated by bioelectrical impedance vector analysis and dilution techniques over a competitive season in athletes. Methods: A total of 58 athletes of both sexes (men: age 18.7 [4.0] y and women: age 19.2 [6.0] y) engaging in different sports were evaluated at the beginning (pre) and 6 months after (post) the competitive season. Deuterium dilution and bromide dilution were used as the criterion methods to assess total body water (TBW) and extracellular water (ECW), respectively; intracellular water (ICW) was calculated as TBW–ECW. Bioelectrical resistance and reactance were obtained with a phase-sensitive 50-kHz bioelectrical impedance analysis device; bioelectrical impedance vector analysis was applied. Dual-energy X-ray absorptiometry was used to assess fat mass and fat-free mass. The athletes were empirically classified considering TBW change (pre–post, increase or decrease) according to sex. Results: Significant mean vector displacements in the postgroups were observed in both sexes. Specifically, reductions in vector length (Z/H) were associated with increases in TBW and ICW (r = −.718, P < .01; r = −.630, P < .01, respectively) and decreases in ECW:ICW ratio (r = .344, P < .05), even after adjusting for age, height, and sex. Phase-angle variations were positively associated with TBW and ICW (r = .458, P < .01; r = .564, P < .01, respectively) and negatively associated with ECW:ICW (r = −.436, P < .01). Phase angle significantly increased in all the postgroups except in women in whom TBW decreased. Conclusions: The results suggest that bioelectrical impedance vector analysis is a suitable method to obtain a qualitative indication of body fluid changes during a competitive season in athletes.

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/m) 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.

This study provides an original data set of body-composition and bioelectric impedance reference values of elite male volleyball players. The results might be useful for interpretation of individual bioimpedance vectors and for defining target regions for volleyball players.

The purpose of this study was to examine the influence of chronological age (CA) and somatic maturation on body composition (BC) and bioimpedance parameters in male elite soccer players. BC and bioimpedance variables were measured in a sample of 249 players aged 9−18 years of age and registered in two professional Italian soccer teams. Results from segmental analysis showed transition time points where the influence of CA and somatic maturation on bioimpedance patterns and BC characteristics increased or subsided. The accelerated phases were assessed for fat free mass, total body water, and upper muscle area, with a starting time point at approximately −2.00 years from peak at velocity (YPHV), and for body cell mass, whose developmental tempo sped up around −1.00 YPHV. An increase in the rate of development was also observed close to −2.00 YPHV for phase angle (PA), although without accelerated phases. From a CA point of view, significant slope changes were found for all BC and bioimpendance variables, except for the calf muscle area. Although the starting points and the span of the accelerated phases were different, they subsided or disappeared at ~ 15 years, except for PA, whose growth waned at ~ 17 years.