## 4 Discussion
This EMG data were derived from a dataset presented in an upper limb study published in 2019 by [PERSON] et al. [39]. The kinematic onset and offset of the movements are shown as well as the two components in which the EMG can be divided. Phasic EMG showed a typical biphasic burst structure, accounting for acceleration and deceleration, respectively, while tonic EMG is modeled with a linear ramp that connects the baseline EMG level before and after movement onset/offset. by analyzing the tonic EMG and then how the transition from static position to movement performance occurs. To hit a tennis ball powerfully, for example, it is fundamental to assume the correct body position before the shot because it is essential to properly transfer the body weight and to guarantee a good balance. The tennis player must position his feet to rotate his hips and bring his arm back by rotating his shoulders, ensuring the proper alignment of the hips and shoulders. This process allows a player to accumulate the necessary energy and release it efficiently, striking the ball with power. The positioning time is very short, but it is important to understand how the muscle contraction acts at that instant to prepare the body to see if the shot will be efficient. Therefore, in this case, the EMG phasic component is dominant because it allows the athlete to perform a rapid movement, but its progression and the height of its burst are highly dependent on the action of the tonic component. Separating the phasic and tonic EMG could lead to a more detailed assessment and understanding of the gesture, as clearly shown in Figure 3, when using upper limb data that were derived from the study published by [PERSON] et al. in 2019 [39]. Moreover, considering also basketball, the separation of the two components may help to shed light on the understanding of the biomechanics of shooting for a basket. Indeed, it has been noted that to be able to make a basket, is important to bend the legs and hips slightly to build up the necessary power while maintaining good stability and balance, and to bend the elbows and wrists to direct the ball towards the basket. As the position  
Figure 3: This figure is an original representation created using the upper limb EMG data presented in [PERSON] et al. [39]. A gray-scale colormap portrays the magnitude of total EMG, phasic EMG, and tonic EMG for upper limb movements when aiming at different targets in the upper limb workspace, showing the very different structure of motion-related and posture EMG components. The muscles analyzed are as follows: erector spinae (ErSp), trees major (TerMa), infraspinatus (InF), lower trapezius (TrLow), middle trapezius (TrMid), upper trapezius (TrUp), anterior deltoid (Dant), middle deltoid (Dmid), posterior deltoid (Dpost), pectoralis (Pect), triceps long head (TrL), triceps lateral head (TrLat), biceps long head (BicLong), biceps short head (BicSh), brachoridailis (Brach), pronator teres (Pron). before the shot is essential to reach the goal, the EMG tonic component has a primary role, while the phasic component is secondary. Indeed, since the shot involves maintaining a correct position, the phasic component acts only at the end to allow the execution of the shot quickly and precisely. A summary of innovative approaches for synergistic control at an algorithmic level is shown in Figure 4. A description of possible innovative lines of action for future research follows. Promoting the use of simulations and digital twinsThere are many tools available that can be used to simulate biomechanics and may impact provisional models capable of improving the understanding of specific sports gestures. Interestingly, some of them may allow us to model many muscles and to apply muscle synergies more comprehensively. It was shown in recent studies that experimental models may neglect some synergies, as only a few muscles are observed [25]. Therefore, simulations and digital twins could provide a more complete picture of a subject's motor control.