B-24 Free Communication/Poster - Body Composition I: JUNE 1, 2011 1:00 PM - 6:00 PM: ROOM: Hall B
PURPOSE: We examined whether exercise performed at the upper limit (85% HRmax) of the ACSM's moderate intensity range has a greater impact on percent body fat (%BF) determined by leg-to-leg bioelectrical impedance analysis (LBIA) and segmental bioelectrical impedance analysis (SBIA) measurements than exercise performed at the lower limit (70% HRmax).
METHODS: Seventy-four college-aged adults participated in this study. Each subject performed two 30-minute moderate intensity (70% HRmax & 85% HRmax) exercise bouts on a cycle ergometer and a control visit on separate days. LBIA and SBIA measured %BF values were obtained immediately before and within 5-minutes of completing the exercise bouts.
RESULTS: Significant differences (P<0.001) in heart rate (141 ± 2.9 vs. 169 ± 3.0 bpm) and OMNI-RPE (4.0 ± 1.5 vs. 6.6 ± 1.6) were observed between the exercise intensities; upper and lower limit, respectively. Following exercise, significant (P<0.05) reductions in %BF were observed when using LBIA (lower limit = 0.3%, upper limit = 0.5%) and SBIA (lower limit = 0.8%, upper limit = 1.4%). Significantly (P<0.04) greater reductions in %BF were observed following exercise at the higher limit for both LBIA and SBIA. When compared to LBIA, the SBIA analyzer demonstrated significantly (P<0.001) greater %BF reductions after exercise at both intensities. When using LBIA, the %BF magnitude of change for the majority of the subjects was ±1.0% after exercise (lower limit = 91%, upper limit = 78%). Conversely, a large percentage of the subjects changed by more than ±1.0% when using SBIA for the assessment (lower limit = 42%, upper limit = 59%).
CONCLUSIONS: Our findings indicate that the intensity of the exercise bout influences the %BF reduction when using LBIA and SBIA for the body composition assessment. Although the magnitude of change after exercise for most participants was within ±1.0% for LBIA, the exercise-induced %BF alterations measured by SBIA demonstrated more variability. Based upon the findings of the present study, we recommend that %BF be obtained prior to the exercise session, especially when using the SBIA technology.