Purpose: The purpose of this study was to examine the effect of resistance exercise (RE) on body composition using air-displacement plethysmography (ADP) within 2 hours of completing RE. Methods: Thirteen university students (9 males and 4 females; 18.8±0.5 yrs; mean ± SD) volunteered for this study. The RE program (55.4±8.7 min) consisted of a combination of upper- and lower-body extremity exercises and abdominal exercises for a total of nine different exercises. Relative body fat (BF) was assessed (1.76+0.4 hr) using ADP before and after the RE along with skinfold (SF) measures, body mass (BM) and respiratory quotient. Results: Statistically significant reductions in pre-post RE relative BF measurements (p=0.036) were observed using ADP along with statistically significant reductions in body volume (BV) (p=0.005), body mass (BM) (p=0.038) and fat mass (FM) (p=0.020). The mean intraclass correlation coefficients (ICC) for these variables was 0.99. No significant pre-post differences in fat-free mass (FFM), body mass index (BMI) or skinfold (SF) values were reported. Conclusions: This study demonstrates the potential adverse effects of assessing relative BF within 2 hours after RE. Significant differences in pre-post relative BF were supported by significant reductions in BV, BM, and FM. The results of this study support the manufacturer guidelines using ADP and RE restriction prior to body composition assessment.
Grossman JC, Deitrick RW. Air Displacement Plethysmography and Resistance Exercise. The Internet Journal of Allied Health Sciences and Practice. 2015 Apr 01;13(2), Article 4.