## 3 Results  
### Included Studies and Study Characteristics  
A total of 222 studies were identified through the PubMed, Scopus, and Web of Science databases. The review included 10 studies after removing 86 studies as duplicates; 115 for not meeting the eligibility criteria after reviewing the titles and abstracts; 3 for including participants who were not adult athletes; 3 for not being RCTs; 3 for lacking a control group without electrical stimulation; and 2 for involving both rugby and soccer players. The flow diagram illustrates the selection process (Figure 1). The 10 studies reviewed included 341 male soccer players (Table 1), aged between 20.9 and 25.7 years, with heights ranging from approximately 1.65 to 1.83 m, and body masses between 63.5 and 79.5 kg. The stimulation sites primarily targeted the quadriceps (vastus medialis, vastus lateralis, and rectus femoris), femoral nerve, calf muscles, glutes, thighs, hamstrings, abdominals, chest, back, and in some cases, the whole body via dermatomeral and metameric pathways (Table 2). The impulse width ranged from 240 to 2500 \(\upmu\)s, whereas the stimulation frequency varied between 1 and 350 Hz (Table 2). The duration of the EMS interventions ranged from a single session to 14 weeks, with training frequency varying from once per week to six sessions per week (Table 2). Among the ten included studies, EMS interventions were associated with improvements in various performance measures. Significant gains were reported in isometric, eccentric, and concentric strength (\(p<0.01\) to \(p<0.001\)) [14], 30-s all-out performance (\(p=0.03\)) [15], quadriceps strength and circumference (\(p<0.05\)) [16], and sprint and jump performance (\(p<0.001\)) [17]. One study reported increased muscle stiffness and decreased elasticity along with improved posture (\(p<0.05\)) [18]. Enhanced muscle fiber diameter (\(p=0.023\)) [19], significant strength improvements across all angular velocities with gains observed in both the dominant and non-dominant legs (\(p<0.05\)) [20], and better performance compared to sham stimulation were also noted (\(p=0.002\) to \(p<0.001\)) [21]. Onestudies in ACL rehabilitation contexts showed significant improvements in functional outcomes at 12 and 16 weeks (\(p<0.001\)) [22]. One study found improved sprint time and reduced lactate levels following an EMS warm-up (\(p<0.05\)) [23]. Figure 1: Flow chart for study inclusion and exclusion process based on PRISMA. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline
**Study** & **Participants (Sex)** & **Physical Characteristics** & **Level** & **Study Design** & **Results** \\ \hline  & & & & & After 3 weeks of EMS training, isometric (\(p<0.01\)) and eccentric \\ [PERSON] et al., 2010 [14] & 20 males & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  \\ [PERSON] et al., 2010 [14] & 20 males & \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  & \ \begin{tabular}{} \end{tabular}  & \begin{tabular}{} \end{tabular}  \\ [PERSON] et al. \begin{table}
\begin{tabular}{l l l l l l} \hline
**Study** & **Participants (Sex)** & **Physical Characteristics** & **Level** & **Study Design** & **Results** \\ \hline  & & & & & The treatment group (TR) showed a significant increase in muscular tone (\(p<0.005\)) but also an increase in \\ [PERSON] et al., 2019 [18] & 20 males & Age: \(25.5\pm 10.6\) years. & Semi-professional & & stiffness and a decrease in elasticity. \\  & & & & The TR group exhibited notable \\  & & & & postural improvements (\(p<0.05\)), & whereas the control group