Relationship between Bioelectrical Impedance Phase Angle and Upper and Lower Limb Muscle Strength in Athletes from Several Sports: A Systematic Review with Meta-Analysis

Use of phase angle as an indicator of overtraining in sport and physical training

The use of bioelectrical impedance analysis (BIA) is now well established in healthcare as an essential support tool for patient management in various clinical settings. Its use in sports is rapidly expanding due to the valuable insights it offers, helping to better structure athletes' diets and training programs, thereby optimizing their performance. In the context of sport, however, there is a consensus regarding the importance of proper interpretation of BIA-derived data, which cannot be limited to mere estimation of body composition. In this sense, therefore, the evaluation and interpretation of raw bioelectrical parameters, including resistance, reactance, and phase angle (PhA) is of relevant importance. The assessment of PhA is particularly significant in the context of sports, as it is closely linked to key factors such as muscle mass, strength, and overall muscle quality. However, the existing relationship between PhA and systemic, and loco-regional inflammation, which, in a broader sense, is the rationale behind its use for assessing and monitoring localised muscle damage. Thus, the importance of PhA monitoring during training becomes evident, as it plays a crucial role in assessing and potentially identifying functional impairments, such as overtraining syndrome, as well as muscle injury and related changes in fluid distribution, at an early stage. The aim of this review is to provide the scientific basis necessary to consider the use of whole-body PhA as an indicator of overtraining.

Sprint and jump performance are determined by localized BIA - an ecological study in track and field adolescent athletes

BACKGROUND

Raw data obtained through bioelectrical impedance analysis (BIA) have been applied in different populations to assess body fluids and cell integrity. Assessing raw BIA parameters in specific muscles is an emerging method for evaluating muscle function. We investigated the associations of the BIA-derived variables of resistance (R), reactance (Xc) and phase angle (PhA) measured through whole-body (WB) and muscle-localized (ML) methods with performance in the countermovement jump (CMJ) and 50-meter (m) sprint.

METHODS

Thirty-one male track and field athletes (16.5 ± 1.6 years) were assessed. Fat-free mass (FFM) and Fat mass percentage (%FM) were determined by skinfold thickness. BIA at 50 kHz was employed to obtain the WB and ML (right thigh) parameters. The WB and ML-BIA parameters were adjusted by height (R/H, Xc/H) and segment length (R/L, Xc/L). The CMJ assessment was conducted via a contact mat; the software recorded the jump height. The 50-m sprint time was measured via two sets of photocells. Pearson's correlation and linear multiple regression were performed.

RESULTS

ML-PhA was inversely related to the 50-m sprint (β=-0.56) and by itself explained 29% of the sprint time variation. It remained a significant predictor even after adjusting for age, height, FFM and peak height velocity (PHV). ML-R/L was directly related to 50-m sprint (β = 0.48) and inversely related to CMJ performance (β=-0.54), explaining 20% and 27% of the variation in 50-m sprint and CMJ performance, respectively. Similarly, it remained a significant predictor in the adjusted models. Correlations between WB-BIA (PhA, R/H) and performance tests were found to be dependent on covariates.

CONCLUSIONS

In this sample, the ML-BIA parameters of R/L and PhA were significantly associated with performance independent of age, height, FFM and PHV. Higher ML-PhA values were associated with better sprint times, whereas higher ML-R/L values were associated with worse sprint times and CMJ performance.

Bioelectrical impedance vector analysis and track and field jump performance across different specialties: Sex differences and electrode configuration

The assessment of athletic performance using non-invasive methods has been a significant focus in research aimed at measuring physiological parameters. This study explores the application of bioelectrical impedance vector analysis (BIVA) among track and field athletes, with a focus on sex differences, electrode configuration, and the correlation between BIVA parameters and jump performances. This cross-sectional study involved 61 Italian track and field athletes: 31 females and 30 males (age: 21.4 ± 3.8; 21.1 ± 2.6 years; stature: 166.1 ± 6.1; 180.1 ± 5.0 cm; body mass: 57.4 ± 9.7; 72.5 ± 10.5 kg, respectively). Anthropometric measurements, bioelectrical impedance analysis, and athletic jump performance were conducted. The RXc graph, two-sample Hotelling's T2 test for BIVA, and one-way ANOVA for specialty comparisons were employed. Pearson and Spearman's tests evaluated the correlations between BIVA parameters and jump performance. Differences in bioimpedance values were observed between athlete groups. Lateral asymmetries were more pronounced in females. Correlations between BIVA and jump performance also varied by sex and electrode configuration, ranging from r = -0.072, p = 0.699-r = 0.555, p = 0.001 in females, and from r = 0.204, p = 0.281-r = 0.691, p = 0.001 in males. This study highlights the utility of BIVA in providing rapid and non-invasive assessments of body composition and its relationship with jump performance, considering variations in athlete sex and electrode configuration.

Raw bioelectrical data and physical performance in track and field athletes: Are there differences between the sexes in the relationship?

Objectives

The study aimed to investigate the relationship between raw bioelectrical data and physical performance in track and field athletes. Specifically, the objectives were to determine: 1) whether a regional bioelectrical impedance approach provides additional insights compared to whole-body analysis, 2) the reliability of the Levi Muscle Index (LMI) in this context, and 3) whether there are differences in these relationships between male and female athletes.

Design

This study utilized a cross-sectional design involving thirty-one female athletes (mean age 21.4 ± 3.8 years) and thirty male athletes (mean age 21.1 ± 2.6 years) from track and field. On a single day, participants underwent whole-body and regional bioelectrical impedance assessments focusing on the lower limbs, alongside strength and speed performance tests.

Results

The study found no significant differences in the relationship between whole-body versus regional bioelectrical impedance and performance tests. Resistance (R) demonstrated an inverse correlation, while phase angle (PhA) and Levi Muscle Index (LMI) showed direct correlations with most performance variables in track and field athletes. Significant differences were observed between male and female athletes across all parameters, with male athletes exhibiting superior performance, higher PhA and LMI values, and stronger correlation coefficients compared to females.

Conclusions

In summary, this study highlights the intricate relationship between body composition and physical performance in athletes. It underscores the importance of considering sex differences and the reliability of raw bioelectrical data, whether obtained through regional or whole-body approaches, in assessing athletic performance.

Could BIA-derived phase angle predict health-related musculoskeletal fitness? A cross-sectional study in young adults

OBJECTIVES

To our knowledge, little evidence exists on the relationships between body composition and health-related physical fitness; in particular, musculoskeletal fitness. Bioimpedance index phase angle (bioelectrical impedance analysis raw variables) is a candidate predictor of health-related fitness, a marker of fat-free and body cell mass, respectively. The aim of this study was to evaluate body composition, raw bioelectrical impedance analysis variables, and health-related fitness in young adults and investigate their mutual relationships to identify predictors of muscle strength.

METHODS

The study included 229 young adults (115 men and 114 women; 24.2 ± 3 y; body mass index 19-30 kg/m²). Anthropometry was measured with standardized procedures. Whole-body BIA (50 kHz) was performed for impedance and phase angle. Predictive equations estimated fat-free mass and percentage body fat. The bioimpedance index was calculated as stature²/impedance. Musculoskeletal fitness was assessed by handgrip strength, standing broad jump, squat jump, and countermovement jump.

RESULTS

In both sexes, health-related fitness had stronger associations with body composition than stature or weight. Handgrip strength was related to fat-free mass and bioimpedance index, while an inverse association with percent body fat emerged for standing broad jump, squat jump and countermovement jump. Phase angle is directly correlated with handgrip strength, standing broad jump, squat jump, and countermovement jump. In multiple regression analysis phase angle was an independent predictor of all health-related fitness tests, along with fat-free mass (or bioimpedance index) for handgrip strength, and with sex and percent body fat for the three jump tests.

CONCLUSIONS

The present study provided consistent information on the relationships between body composition and health-related fitness in young adults. Phase angle emerged as a significant predictor of all health-related fitness measures and might be useful for a more consistent assessment of musculoskeletal fitness.