## 4 Discussion
### The Effects of EMS on Sports Injury Recovery  
Players are frequently required to perform rapid changes in direction, sudden stops, jumping, and forceful physical confrontations due to the high-intensity and contact-heavy nature of soccer [33]. These repetitive high-load movements place considerable stress on the knee joint, making soccer players particularly susceptible to anterior cruciate ligament (ACL) tears [34]. The two reviewed studies provide consistent indications that neuromuscular electrical stimulation (NMES) can serve as a supportive component in rehabilitation following ACL reconstruction, particularly in professional soccer players [16; 22]. [PERSON] and [PERSON] (2024) [22] reported notable improvements in quadriceps strength, pain levels, and daily functional performance following the application of NMES, along with measurable changes in muscle activation as assessed by needle electromyography. These findings suggest that NMES may help mitigate early postoperative quadriceps inhibition by enhancing motor unit recruitment and voluntary muscle activation [35]. Similarly, [PERSON] et al. (2013) [16] provided evidence supporting the effectiveness of NMES in improving muscle strength and cross-sectional area over a short intervention period. Taken together, NMES may assist in accelerating strength recovery and potentially facilitate earlier progression to functional tasks such as running and agility training. Although the two studies differ in stimulation protocols and evaluation methods, both demonstrate favorable outcomes associated with the use of NMES in ACL rehabilitation. Nonetheless, further studies are needed to determine optimal stimulation parameters and to evaluate the long-term effects of NMES, particularly in diverse athletic populations.  
The study by [PERSON] et al. (2019) [18] showed that electrical stimulation improves posture and muscle tone in soccer players, potentially contributing to enhanced athletic performance and reduced injury risk. However, despite improvements in muscle tone and stiffness, a decrease in muscle elasticity, particularly in the hamstrings, was observed. This reduction in elasticity might be related to increased muscle stiffness, which can make muscles less flexible and slower to recover after stretching or contraction. While increased stiffness may aid in injury prevention by enhancing joint stability, it can also impair the muscle's capacity to stretch and rebound, which may negatively affect performance [36; 37]. The intervention in this study emphasized spinal reflex activation through cutaneous receptors, modulating the myofascal system and postural control. In contrast, [PERSON] et al. (2012) [15] applied VEINOPLUS(r) blood-flow stimulation technology, which focused on activating the calf muscle venous pump to improve peripheral circulation and accelerate metabolite clearance. Although this approach did not significantly reduce muscle damage markers or improve maximal strength, it was associated with faster recovery of high-intensity anaerobic performance compared to passive recovery. This finding suggests its potential practical value in alleviating short-term metabolic fatigue during intermittent competition. Despite differences in underlying mechanisms, both studies demonstrated beneficial effects of specific forms of EMS on athlete recovery processes.