Association between phase angle and body composition components in adolescent athletes: a cross-sectional study

Abstract Objective. To investigate the association of phase angle (PhA) with body fat percentage, lean soft tissue, and bone mineral density (BMD) in adolescent athletes overall and stratified by sex and sexual maturity stage. Approach. A cross-sectional study was conducted with 112 adolescent athletes (67 boys, 14.25 ± 2.08 years) who practiced indoor volleyball, beach volleyball, swimming, Track and Field, or basketball. BMD, lean soft tissue, and body fat percentage were estimated using dual-energy x-ray absorptiometry. PhA was determined using bioelectrical impedance analysis (50 kHz). Associations between PhA and body composition were tested using multiple linear regression in three models: (1) total sample, (2) stratified by sex, and (3) stratified by maturation. Covariates generally included skin color/race, sport modality, time in the sport, and weekly training volume. Main results. In the overall sample, PhA showed a negative association with body fat percentage and a positive association with lean soft tissue and BMD. When the results were stratified by sex, there was a negative association with fat percentage in girls and positive associations with lean soft tissue and BMD in boys. Analysis by sexual maturity stage revealed that PhA was negatively associated with body fat percentage in pubertal athletes and positively associated with lean soft tissue and BMD in both pubertal and post-pubertal athletes. Significance. PhA was positively associated with lean soft tissue and BMD and negatively associated with fat percentage. However, associations varied by sex and sexual maturity, underscoring the importance of accounting for these biological variables when assessing relationships between body composition and PhA in athletes.