RESUMEN

The purposes of this investigation were to determine: 1) whether a structured in-school physical education exercise bout altered the leg-to-leg bioelectrical impedance analysis (LBIA) determined percent body fat (%BF) value; and 2) whether the potential exercise-induced %BF magnitude of change altered the health risk classification of the child. Seventy-six girls (age: 12.2±1.0 yr; height: 153.9±7.5 cm; body mass: 51.9± 15.5 kg; BMI: 21.7±5.4 kg/m2) participated in this investigation. LBIA measured %BF values were obtained immediately before and within 5-min after completing a structured, in-school, physical education class. Significant reductions (p < 0.001) in mean %BF (25.0±10.2 vs. 24.4±10.3 %) were observed for the group following the physical education class. For the majority of the girls (88%), the %BF alteration was less than ± 2.0 %BF. More specifically, the %BF magnitude of change was ±1.0 %BF in 64.5% of the girls, between 1.1 and 2.0 %BF in 23.7% of the girls, and by more than 2.0 %BF in 11.8% of the girls. Regardless of the %BF magnitude of change, all girls remained in the same adiposity classification category (healthy vs. unhealthy body fat) following exercise. Adhering to the pre-test exercise guideline appears unnecessary when using LBIA to categorize the health risk of an adolescent girl.