## 2 Materials and Methods
### Variables and Measurements  
The dependent variable (BF%) was calculated by applying the equation established by the Clinica Universidad de Navarra, the CUN-BAE [28], as follows:  
\[ \begin{array}{l}\text{CUN-BAE (BF\%)}=-44.988+(0.503\times\text{Age})+(10.689 \times\text{Sex})+(3.172\times\text{BMI})-(0.026\times\text{BMI}^{2})\\ +(0.181\times\text{BMI}\times\text{Sex})-(0.02\times\text{BMI}\times\text{ Age})-(0.005\times\text{BMI}^{2}\times\text{Sex})+(0.00021\times\text{BMI}^{2}\times\text{Age})\end{array}  \tag{1}\]The age of the athletes was measured in years, and sex was codified as female = 1 and male = 0. BMI was calculated as weight in kilograms (kg) divided by height in meters squared (m\({}^{2}\)). Currently, the four categories of BMI used to estimate weight in adults are as follows: (1) underweight status (BMI \(<\) 18.5 kg/m\({}^{2}\)); (2) a healthy weight for adults (BMI = 18.5-25 kg/m\({}^{2}\)); (3) overweight status (BMI = 25-30 kg/m\({}^{2}\)); and (4) obese adults (BMI \(>\) 30 kg/m\({}^{2}\)) [38]. For the CUN-BAE, the cut-off points for body fat were considered to be normal (BF% \(<\) 20% in males and \(<\)30% in females), overweight (BF% ranging from 20 to 25% in males and from 30 to 35% in females), and obese (BF% \(>\) 25% in males and \(>\)35% in females) [28; 39]. The body composition analyzer used in our study was manufactured by Jawon Medical, developed in cooperative research with Korea and Japan from 1996 to 1999, and commercialized in 1999. More specifically, the independent variable (BF%) was estimated using the BIA [20] technique (the body composition analyzer X-Scan Plus (the International Organization for Standardization adopted by the European Union (EN-ISO): 13488 [40], Seoul, South Korea). The assessment of body composition was performed according to the protocols recommended by [PERSON] at al. [41] and [PERSON] [42]. The X-Scan Plus prediction equations were developed based on body composition estimates derived from an a priori criterion, namely an isotope dilution approach. The X-Scan Plus bioelectrical impedance analyzer operated at multi-frequencies of 5, 50, 250, 550, and 1000 kHz and was suitable for providing outcomes such as fat-free mass and BF% via eight touch electrodes (with two on each foot and two on each hand). Moreover, using the multi-frequency technology at low frequencies (\(<\)50 kHz) allowed the bioelectric current to pass through the extracellular fluid in the human body. In contrast, at frequencies above 100 kHz and up to 1000 kHz, the bioelectric current could pass through all body fluids and tissues [8; 17]. Thus, the multi-frequency bioelectrical impedance analysis provided enhanced body composition outcomes in a time-efficient (\(\leq\)5 min) manner. It should be highlighted that the estimates of BF% and fat-free mass obtained from the multi-frequency bioelectrical impedance analysis demonstrated good agreement with a four-compartment model in normal-weight adults [43]. Furthermore, the X-Scan Plus had a built-in stadiometer for the measurement of standing height to the nearest 0.1 cm [42]. It should be highlighted that the X-Scan Plus device had an auto-calibration function that was used every time the device was turned on. Thus, the absence of the need to calibrate the X-Scan Plus device could also be considered an advantage of this study. The accuracy of the weight measurements was ensured in the presence of a sports nutritionist throughout all of the investigation procedures. However, auto-calibration of the X-Scan Plus device was performed whenever the weight measurements seemed incorrect. In addition, athletes should avoid exercise (\(>\)24 h) before the measurement procedure to restrict the influence of muscle damage or injury, increases in body temperature, excessive sweating, or the accumulation of skin electrolytes. Also, some scientific data have proposed that glycogen depletion in the muscles and loading may impact BIA measurements [44].