## 4 Discussion
### Whole-Body Bioelectrical Changes Evoked by Training  
Several studies analyzing whole-body BIVA show same impedance patterns as in the present study, reporting an increase in R/h and Xc/h parameters, as well as a vector migration along the major axis induced by short-term physical exercise [41, 43, 48, 50]. The increase in R/h can be easily explained by the body fluid loss previously mentioned,since R is the opposition of the conductor to the current flow [41]. The loss of body fluid triggers a decrease in BM and a decrease in the percentage of total amount of body water.  
Contrary to R/h, the changes of Xc/h were not significant, although a similar tendency of the kinetic of this parameter to other studies was clearly seen [41; 43], increasing at POST and decreasing at the recovery period (POST24H). However, the kinetic of Xc is not as easy to explain, and [PERSON] and [PERSON] in the book of [PERSON] and [PERSON] [51] indicated that the variation of this parameter may be produced as a consequence of two different but related cellular adaptations. The first is fluid shifts between intracellular and extracellular compartments. Regarding this topic, [PERSON] et al. [50] observed that changes in Xc/h were negatively related to plasma osmolarity changes; therefore, lower intracellular fluid losses mean greater plasma osmolality increases. The second is modifications in cell size affecting dielectric mass (cell membrane and tissue interfaces), as physical exercise generates acute processes that modify the characteristics of muscle cells, as the cell membrane becomes thinner, the cell swells, and capacitance increases, and the opposite happens as the cell shrinks, thus affecting Xc [41]. However, this kinetic needs to be studied further since multiple factors may affect Xc changes after performing exercise [13] and, as we previously mentioned, BIVA at 50 kHz does not penetrate inside the membrane cell and non-intracellular information is obtained [41]. Furthermore, as shown in Figure 5, six of the subjects reported the same pattern throughout the intervention; however, there was one subject for which the Xc/h kinetic was different from the rest at POST. There is not enough information to determine what happened to this specific subject, since he followed the same protocol and the same training session as the rest of the analyzed subjects.  
A significant increase in the vector length (\(9.6\pm 5.7\%\)) was observed, which, according to the body weight change, confirmed a loss of fluid since the length of the vector is inversely related to total body water (TBW) [32]. In fact, [PERSON] et al. [52] reported that subjects who realized a cycling test to exhaustion on a cycle ergometer without dehydration through drinking during the training did not have a significantly altered vector length, as opposed to those who did not drink and became dehydrated. Furthermore, the cyclists in a state of dehydration had a worse performance, since hypohydration states attenuate strength by approximately 2% and power by approximately 3% [53].  
At POST24, R/h significantly decreased by 4.8 \(\pm\) 3.1%, a fact that, in conjunction with the recovery of body weight and the shortening of the length vector (\(-4.8\pm 3.2\%\)), indicated that the players were not dehydrated anymore and had recovered the fluid lost during training. Still, there were no significant changes regarding Xc/h at POST24H. However, regarding PRE, the direction of the vector changed since there was a significant difference between the PRE and POST24H PhA; hence, it was supposed that the ICW/ECW ratio had changed. In the sports field, a decrease in PhA can mean conditions of fatigue [54] or cell damage [20; 21; 22; 23; 24], thus this information could help physical trainers to assess the workload in their players.