Effect Of Exercise Intensity On Percent Body Fat Determined By LBIA In Adults

Abstract

PURPOSE: To examine the effect that exercise intensity had on percent body fat (%BF) measured by leg-to-leg bioelectrical impedance analysis (LBIA) in adults METHODS: Forty-two college aged adults (21 women; 21 men) participated in this study. Each subject performed two 30-minute cycle ergometry exercise bouts of varying intensity on separate days. LBIA measured %BF values were obtained immediately before (PRE) and within 5-minutes of completing the exercise bouts. RESULTS: The average intensity of the exercise sessions corresponded to 65% and 80% of age-predicted maximal heart rate. Significant differences (p<0.001) in heart rate (129 ± 8 vs. 157 ± 7 bpm) and total caloric expenditure (150 ± 32 vs. 207 ± 37 kcal) were observed between the exercise intensities. For the lower intensity exercise bout, significant (p<0.05) reductions in %BF (mean difference = 0.3% and 0.7%) and body mass (mean difference = 0.1 and 0.4 kg) were observed in the women and men, respectively. Similarly for the higher intensity exercise session, significant (p<0.05) reductions in %BF (mean difference = 0.4% and 0.5%) and body mass (mean difference = 0.2 and 0.6 kg) were observed in the women and men, respectively. CONCLUSIONS: Although minimal, cycle ergometry exercise decreased LBIA-determined %BF in this study (<0.7%). However, the magnitude of change was unaffected by the two exercise intensities under examination (65% and 80%). Comparable intensities are often used to define a target heart rate zone during cardiorespiratory exercise prescription. When performing aerobic exercise within this intensity range, whether the LBIA assessment of %BF occurs before or after the exercise bout appears to have little practical significance in the health-fitness setting.