## 4 Discussion
### Localized Bioelectrical Changes Evoked by Training  
There were important pattern differences in the impedance vector changes analyzed in the rectus femoris muscle compared to those of the whole-body. To date, the studies analyzing muscle-localized BIVA short-term changes are completely different from the present study, and they analyze the impedance behavior in the biceps brachii during a fatiguing protocol exercise with resistances [55; 56; 57; 58]; thus, there are no localized BIVA assessment studies focused on short-term adaptations in team sports training. This matter is important since the nature of the exercise is different and the muscle impedance adaptations can also be different; therefore, this should be considered when making comparisons. According to muscle-localized BIVA studies, the kinetic of R is expected to decrease at the end of the training. [PERSON] et al. [58] attributes three main reasons to explain this phenomenon: an increase in muscle blood flow, an increase in vasodilation, and an increase in muscular electrical conductivity due to an increase in metabolites. In this study, an increase in R/h was also reported; however, these differences were not significant despite the fact that a clear tendency was observed. Another matter of interest was the possible correlation between R/h and muscle swelling, since muscle swelling is mainly due to fluid accumulation in the region and reduces the tissue resistance [57]. [PERSON] et al. [58] reported significant impedance adaptations, both in R and Xc, at the maximum muscle swelling post-training. In the present study, such a correlation was not found, since non-significant adaptations were registered for localized R/h. A possible explanation for this lack of significance was that the fluid accumulation in the thigh was not as pronounced as that produced by resistance training. Additionally, a slight dehydration of the entire body renders R/h as a less appropriate parameter for evaluating the adaptations of this type of training exercise. The Xc/h PRE-to-POST changes reported a significant increase (38.7 \(\pm\) 44.7%), which was surprising since these results do not match with most previous localized-muscle studies [56; 57; 58]. The kinetic of Xc has yet to be clarified; however, it seems clear that is related to cell integrity, as it is not only altered as a consequence of muscle damage produced by strenuous exercise, but also when an injury occurs. In this regard, several studies show that the more severe the muscle injury is, the greater the reduction in the reactance component, which returns progressively to its pre-injury values while the subject recovers from the injury [20; 21; 22; 23; 24]. At POST24H, Xc/h significantly decreased beyond PRE-values, which could imply that muscles were not yet fully recovered. The characteristics of the sample, the type of training load, the assessment conditions, and the total workout time could have influenced these values. A possible hypothesis for this fact is related to cell adaptations, since after the dehydration produced by exercise, the main effect of losing extracellular fluid is to expel water from the interior of the cell such that the membrane thickens and the capacitance decreases, thus increasing Xc. In contrary to the aforementioned localized BIVA studies on biceps [55; 56; 57; 58], there were no dehydration processes and the type of exercise promoted the accumulation of fluids in the exercised muscles, and the reverse mechanism could have occurred, hence the increasing Xc. This hypothesis cannot be demonstrated in the present paper as we lack the information on the adaptations occurring at intracellular level; thus, future studies could be targeted to this topic. [PERSON] et al. [59] analyzed the impedance impact of botulinum toxin injections on spastic muscles and reported a significant decrease in resistance, while no change was reported for reactance.