## 2 Materials and Methods
### Procedures  
Prior to starting the research, the experimental procedures were explained to the participants, who gave their voluntary written informed consent in accordance with the Helsinki Declaration, ensuring ethical standards were met, with ethical approval granted by the European University's Bioethics Committee under code CIPI/18/074. Then, the following variables were measured the hour before the race and immediately after finishing the race. Cortical arousal was analysed through the critical flicker fusion threshold (CFFT) in a viewing chamber which was constructed to control extraneous factors that might distort CFFT values (Lafayette Instrument Flicker Fusion Control Unit Model 12021) following the procedures conducted in previous studies [18; 19]. An increase in CFFT suggests an increase in cortical arousal and information process; by contrast, when the values fall below the baseline, it suggests a reduction in the efficiency of processing information and fatigue of the central nervous system [7]. Blood oxygen saturation (BOS) and heart rate (HR) were measured with a pulse oximeter (PO 30 Beurer Medical) following previous procedures [20]. Body temperature (BT) was measured with a digital infrared thermometer (Temp Touch; Xilas Medical, San Antonio, TX, USA) following previous authors [21; 22]. Lower body muscular strength manifestation was analysed using a vertical jump test. We used the Sensorize FreePowerJump system (SANRO Electromedicina, Madrid, Spain), which recorded flight time (s) and jump height (cm) to evaluate 2 vertical types of jump following previous protocols [23; 24]. Participants performed 2 Contramovement Jumps (CMJ) and 2 Abalakov jumps (ABK), as in previous research [19; 25]. The coordinative capabilities and arms utilization capacity (CCA) were also analysed using the Bosco formula (1999) (CCA= ABK - CMJ)  
Upper body muscular strength manifestation was analysed by testing the isometric hand strength (IHS) with a grip dynamometer ([PERSON], Tokyo, Japan). Two repetitions were performed with the dominant hand, and the best one was chosen in line with previous research where performance was measured [26; 27]. The blood lactate concentration was measured by taking a sample of 5 uL of capillary blood from a finger and analysed with the validated Lactate Pro Arkay, Inc. system (Kyoto, Japan) according to previous research [28]. Urine samples were collected to analyse dehydration levels, which were examined against a urine colour chart (colour range 1-8, where 1 = very pale yellow urine, which reflected a good level of hydration, and 8 = very dark yellowish brown, which reflected a significant level of dehydration); the number closest to the sample colour was recorded [29]. Urine nitrates, protein, glucose, and pH were measured with the Orine Combur Test (Roche, Madrid, Spain) stripes. The rate of perceived exertion (RPE) was measured with a Borg 6-20 scale [30]. Spirometry values of forced vital capacity (FVC), forced expiratory volume in 1 s (Fev1), and forced expiratory flow 25-75% (FEF25) were measured using a CPX device (Medical Graphics Corporation, St. Paul, MN, USA) performing maximum inhale-exhale-inhale cycle as previous research [31]. Kinematics of the scapula were measured with a scapular dyskines test. Participants performed 3 shoulder 180\({}^{\circ}\) flexions and 3 shoulder 180\({}^{\circ}\) abductions. Values were classified into 3 grades: normal pattern, subtle dyskinesia, and evident dyskinesia [15]. Lower limb stability was measured with the 1-leg standing test (1 LST). Participants performed one repetition of 30 s with each leg at 90\({}^{\circ}\) of hip and knee flexion with their eyes closed. Values were also classified into 3 grades: I. The athletes remained the whole 30 s without falling, collapsing their hips (Trendelemburg sign) or pivoting with their feet, which indicates good stability; II. The athletes remained the whole 30 s, but their hips collapsed and/or feet pivoting occurred, which indicates poor stability; III.