How is the phase angle associated with total and regional bone mineral density in university athletes? *

Objective.To investigate how phase angle (PhA) is associated with total and regional bone mineral density (BMD) (femur and lumbar spine) in university athletes.Approach.This cross-sectional study was conducted in Florianópolis, Brazil, with 167 university athletes from different sports (92 males). The PhA was obtained through electrical bioimpedance and BMD was obtained through dual x-ray absorptiometry (DXA). Data on the covariables age, time involved in the sport, type of sport (low, medium and high impact), daily use of oral contraceptives, and vitamin D calcium and/or protein supplementation were obtained through anamnesis, while fat mass and fat- and bone-free mass were obtained through DXA. Simple linear regression and a 5% significance level were used.Main results. In female athletes, PhA was directly associated with total BMD (β: 2.20; 95% CI: 0.43; 3.96) and BMD in the femur (β0.85; 95% CI: -0.23; 1.94) and lumbar spine (β: 1.45; 95% CI: 0.44; 2.46), even after adjusting for the covariates. In male athletes, although PhA was directly associated with regional BMD (femur [β: 0.63; 95% CI: 0.04; 1.22] and lumbar spine [β: 0.64; 95% CI: -0.01; 1.31]) in simple linear regression, this association disappeared when the covariates were added.Significance. PhA was directly associated with total BMD and lumbar spine in female, but not male, athletes.