Phase angle and its determinants among adolescents: influence of body composition and physical fitness level

Objective To examine the association between levels of physical fitness, parameters of body composition and phase angle amongst adolescents. Methods A total of 152 adolescents (84 girls) aged 11–16 years were included in this study. Flexibility, abdominal strength, upper and lower limb strength, agility, speed and cardiorespiratory fitness were analysed. Generalized Linear Models were applied to verify significant differences across sexes. Stepwise linear regression was used to establish an association between the variables studied. Results The study established a significant association between PhA and weight, FFM, BMI, FM, %FM and medicine ball throw (MBT) for girls. As for the boys, a significant association was verified between PhA and weight, FFM, BMI, standing long jump (SLJ), MBT and the three allometric VO _2peak variables analyzed. A negative association was found between PhA and the boys’ square agility test (SAT) and 20-m shuttle run test (20SRT). Conclusion Boys showed a greater phase angle than girls; In girls, BMI and %FM, were determinant of 32.4% (r = 0.57). PhA variability which is influenced by physical fitness, body composition and, therefore, the tissues electrical conductivity. Furthermore, boys’ height, FFM, upper limb strength, and agility account for 58.4% (r = 0.76) PhA variability. There was a positive correlation between the physical fitness tests and the PhA.