"Lower Body Resistance Exercise on Body Composition Parameters Assessed by DXA" by Mathis Rollin, Elizabeth Hardy et al.
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Abstract

Dual-energy X-ray-absorptiometry (DXA) analysis has the capability to measure bone mineral content (BMC), fat mass (FM), and lean mass (LM), also known as a 3-compartment model. Various factors such as exercise, hydration status, glycogen status, and others are thought to influence the accuracy of DXA estimated body composition. PURPOSE: The purpose of this study is to investigate acute changes in DXA LM and FM results pre-and-post prescribed lower body exercise compared to a non-exercise treatment. METHODS: Participants (n = 14; 22.71 ± 1.63 years; 169.42 ± 13.23 cm; 80.79 ± 17.71 kg) completed each trial that consisted of two treatments in a randomly assigned crossover experimental design: resting conditions (REST) or a prescribed lower body workout (LBRE) consisting of 4 sets of 12 repetitions on leg press, leg curls, leg extension, and kettlebell squat. At each visit, height, weight, and urine specific gravity were measured. DXA scans were performed before and 60 mins after REST or immediately after LBRE. Linear mixed-effects models were used to evaluate each outcome variable. The fixed effects included time, condition, and their interaction. Random intercepts were included to account for between-participant variability. The model was fitted using restricted maximum likelihood estimation. Data was analyzed using R software. RESULTS: DXA total mass, total LM, total FM, and total body fat percentage were unaffected by the lower-body exercise session (p>0.05 for all model coefficients). Similarly, no segmental LM or FM variables were influenced by the exercise session (p>0.05 for all model coefficients). CONCLUSIONS: An acute bout of lower body resistance exercise does not meaningfully influence DXA estimates of body composition parameters in a recreationally active population. Thus, guidelines suggesting to abstain from resistance exercise prior to a DXA might not be essential, which could allow for greater flexibility in scheduling of body composition assessments.

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