# Body Composition in Karate: A Dual-Energy X-ray Absortiometry Study
## 2 Materials and Methods
### Anthropometry and Body Composition Analysis  
An electronic scale (Tanita electronic scale BWB-800 MA) was used to measure body mass to the nearest 0.1 kg: a Harpenden stadiometer (Holtain Ltd., Crymych, UK) was used to measure stature to the nearest mm according to standard procedures [28] (intra-rater error \(\leq\)0.15% for body mass and \(\leq\)0.10% for stature). Body mass index (BMI) was calculated as weight (kg)/height (m\({}^{2}\)). Body composition was evaluated in terms of bone mineral content (BMC) (and bone areal density (aBMD)), fat-free soft tissue mass (FFSTM), and fat mass (FM) by means of a total body DXA scanner (QDR Horizon, Hologic, Marlborough, MA, USA; fan-beam technology, software version 13.6.05). For the quality control checking of baseline drift, the reference phantom obtained from the manufacturer was used daily. For the sake of consistency, the same researcher carried out all examinations. The participants were scanned in the late morning after voiding when fasted for at least 4 h. The participants were required not to exercise vigorously in the 24 h before examination. DXA scans were performed at least 10 days before or after competition, thus representing close to \"competition body composition\", yet before acute weight loss/gain had begun. The participants were in light clothing and removed any metal or reflective material. All measurements were performed according to [PERSON] et al. [29]. Scans were taken of the whole body (WB). The in vivo measurement short-term precision was calculated according to standard criteria [30]; in particular, repeated (n = 2) scanning of 30 subjects with repositioning was carried out. The precision (percent coefficient of variation) was 2.12%, 0.59%, 0.75%, 2.19%, and 0.68% for FM, FFSTM, BMC, %FM, and aBMD, respectively. The following regions were identified in the WB scans with the aid of the Hologic software and eventual correction by one researcher: head, trunk, upper limb (left and right), and lower limb (left and right). The BMC and aBMD values in the total body less head (TBLH) region were used for analysis as recommended in [31], also considering that a large proportion of total body mineral is contained in the skull, which is not easily amenable to changes induced by physical activity [32]. However, WB values for BMC and aBMD were also reported in the results for the sake of comparison with the previous literature. For the purpose of this work, FM, FFSTM, BMC, and aBMD were also calculated for the lower limbs together (Legs) and the four limbs together (Appendicular). In our sample of karate participants, stature and body mass were confounding variables, especially for bone measurements, because DXA is a projectional technique and DXA-derived measurements do not adequately correct for body and/or bone size [33]. Accordingly, the soft tissue body composition variables were also expressed either as a proportion to total body mass or normalized by square stature (fat mass index, FMI; fat-free mass index, FFMI) [34]. The bone mineral was expressed as bone mineral apparent density (BMAD, g/cm\({}^{3}\)) according to the formula proposed by [PERSON] et al. [35]: BMAD = BMC/(bone area\({}^{2}\)/body stature).