## 4 Discussion  
The purpose of the study was to analyze the effect of an FEMD-controlled intra-set variable resistance PAPE protocol on the throwing velocity of female handball players. Two hypotheses were established: (a) the IsVR PAPE potentiation protocol increases throwing velocity in female handball players, and (b) a number of potentiation sets are required to increase throwing velocity. Our results show that the FEMD-monitored IsVR PAPE protocol significantly increases throwing velocity, and at least two potentiation sets at 30% and 60% of 1 RM are required when the PAPE is controlled with an FEMD. The results of this research are related to the study by [PERSON] [8], which suggests that 2-3 sets of six repetitions at an intensity of \(>\)70% of 1 RM are effective for power and throwing performance in well-trained athletes. The study by [PERSON] et al. [24] implemented a PAPE protocol of bent-over barbell rows, bench presses, or push-ups with two sets of four repetitions at 60% and 80% of 1 RM in professional female softball players, reporting significant improvements similar to those in this study in medicine ball throwing. The choice of sub-maximal intensities is due to the fact that both stronger and weaker individuals respond better to variable CV stimuli when the stimuli are higher [42]. The correct exercise volume should be considered and should be adjusted because there is a significant effect of strength training experience on time under muscle tension and the number of repetitions of each set [43]. For athletes at a competitive level, BP intensity possibly generates increased motor unit recruitment (type II) [25]. In the study by [PERSON] et al. [26] investigating flywheel training, specific inertial loads (0.041 kg m\({}^{2}\), 0.057 kg m\({}^{2}\), and 0.122 kg m\({}^{2}\)) were used with three-minute pauses between sets with PAPE occurring between minutes four and eight after the conditioning activity (AC), with significant effects at intermediate and high intensities. Similarly, a study by [PERSON] et al. [27] evaluated the effect of drop jumps (DJ) on hard and sand surfaces using a crossover design with a fixed height of 60 cm and recovery pauses of seven and 15 min between the AC and subsequent performance measurements, highlighting that the surface did not show significant differences in PAPE responses in elite sprimters due to the high interindividual variation in their responses. In the study by [PERSON] et al. [28], the use of VR with elastic bands adjusted to 85% of 1 RM load in back squat exercises showed a significant increase in jump height, power, and the rate of force development, while the use of fixed resistance with free weight at 85% of 1 RM did not produce significant changes. Although these studies were able to induce PAPE under certain conditions, they did not implement a specific control for the intensity and load applied during AC, unlike our study using FEMD, in which the physical load and intensity to be used in exercises with IsVR were specifically controlled. This allowed for real-time dynamic adjustments, such as optimizing the load applied in each repetition and maximizing the stimuli to achieve PAPE. Possibly, the control of the physical load and intensity changes can be a determining factor to induce changes in performance to adapt the stimuli to the specific demands and gestures of the sport, such as handball throwing. The results of our study do not agree with those of [PERSON] et al. [31], where female athletes reported a non-significant improvement in their throwing velocity after using the unilateral standing bench press and a five-repetition protocol with an initial velocity of 0.6 m\(\cdot\)s\({}^{-1}\) and a final velocity of 0.9 m\(\cdot\)s\({}^{-1}\) in a \"unilateral chest press\" with the dominant arm in standing position with the FEMD device.