## 2 Materials and Methods
### Procedures
#### 2.3.2 Bioimpedance Assessment
Body temperature was measured just before the BIA measurements; this verified the return to temperatures close to the pre-training values, thus no significant differences were recorded between individual body temperatures of each player (PRE: 37.1 \(\pm\) 0.2 \(\lx@math@degree\)C; POST: 37.3 \(\pm\) 0.5 \(\lx@math@degree\)C; POST24H: 37.2 \(\pm\) 0.3 \(\lx@math@degree\)C). The measurements of body temperature before and after the training session were performed with a tympan thermometer in the right ear (Genius 1000, Sherwood, Nottingham, UK, measuring range: \(-25+55\)\(\lx@math@degree\)C, accuracy: 0.1 \(\lx@math@degree\)C) connected to a \"data logger\" Squirrel 2010 model (Grant Instruments Ltd., Cambridge, UK). Ambient temperature and relative humidity were recorded every 30 min during the total duration of the training by a portable weather station (Kestrel Weather K4500, TEquipment, USA, temperature measurement range: \(-29+70\)\(\lx@math@degree\)C; accuracy: \(\pm 1\)\(\lx@math@degree\)C), and the average was \(22.3\pm 0.4\)\(\lx@math@degree\)C for room temperature and 55.2 \(\pm\) 1.5% for relative humidity. The bioelectrical measurements were conducted under controlled conditions through the 50 kHz single frequency tetrapolar technique [32]. The subjects were measured lying on a stretcher in the supine position with their arms separated from their body by 30 degrees and their legs apart from each other at 45 degrees to avoid adduction or crossing of limbs, which would shorten the circuit and reduce the impedance values [38]. The electrodes were placed using the anatomical landmarks identified by palpation and reference distances with the anthropometric tape, to measure localized spots of the selected muscles. Pre-gelled electrodes (Red DotTM 2660-5, 3M Corporate Headquarters, St. Paul, MN, USA) with low impedance were used to minimize the measurement error produced by the bioimpedance between the electrodes and skin. The area where the electrodes were placed was shaved and cleaned with alcohol. The points at which they were placed were labelled with permanent marker to ensure that the location was identical before and after training. The bioelectrical measurements were recorded after a stabilization period of 5 min, in which the players remained lying motionless. From the 5 min mark, three measurements were performed every 60 s to ensure proper distribution of body fluids. Subsequently, the average value for the three measurements was used for the final calculations. * Whole-body assessment: The proximal electrode (sensor) of the arm was placed on the dorsal surface of the right wrist, between the ulna and radius. The proximal leg electrode was placed on the anterior surface of the right ankle, between the protruding portions of the bones. The distal electrodes (nozzles) were placed on the dorsal surface of the third proximal phalanx of the right hand and foot [16]. The proximal electrodes were spaced 5 cm from the distal to prevent interaction between electric fields, which could lead to an overestimation of the impedance values. * Rectus femoris muscle-localized assessment: The electrode placement procedures followed the recommendations of the Surface Electromyography for the Non-Invasive Assessment of Muscles (SENIAM) guidelines for the rectus femoris [39] and the ISAK standards and measurement protocol [35], as follows: 1. Locate the anterosuperiori iliac spine (sartorius insertion), assuming that a more inferior (anteriorifier iliac spine) rectus femoris origin, and mark with a point; 2. Locate the superior pole of the patella with the knee in unforced extension, and mark with a point; 3. Connect both mark points with an anthropometric tape (running in a straight line along the immediately upper anterior thigh). Note the distance, in cm, between the two points and mark at 50% of this distance with a dot; 4. Placement of the electrodes: divide the distance between the origin and insertion by three.