## 4 Discussion
These adaptations were particularly evident between weeks 8 and 26 after surgery. Interventions incorporating high-intensity eccentric or isometric contractions of the contralateral limb were effective in attenuating muscle strength deficits [46; 48]. For example, [PERSON] et al. [17] demonstrated that high-intensity eccentric CE produced greater quadriceps strength gains (+31%) compared to concentric CE or conventional rehabilitation. Conversely, [PERSON] et al. [18] found no significant improvements when CE was performed with lower intensity or delayed in the postoperative timeline, highlighting that both the load magnitude and timing of implementation are key determinants of clinical outcomes. Regarding neuroplastic effects, direct evidence in ACLR populations is scarce. Only the case series by [PERSON] et al. [44] employed a CE-based intervention and their study provided relevant data by analyzing the relationship between quadriceps motor unit properties and corticospinal excitability in ACLR patients. Their results showed that lower discharge rates and poor motor unit recruitment were associated with reduced excitability in the primary motor cortex. These findings support the idea that postoperative functional deficits may be mediated not only by peripheral factors but also by central mechanisms, which could be modulated through strategies like CE. Nevertheless, most studies in this area come from research on healthy individuals or those with different neurological conditions, such as stroke or unilateral immobilization. These studies provide additional evidence on potential neurophysiological mechanisms of CE, including increased primary motor cortex excitability, reduced intracortical inhibition, and functional changes in interhemispheric connectivity [56; 57; 58]. Collectively, the findings of this scoping review support the potential of CE as a complementary tool in designing postoperative ACL rehabilitation programs, particularly in early phases where direct training of the affected limb is limited. The possibility of preserving or even improving muscle strength and functional performance through stimuli applied to the non-injured limb could help reduce inactivity time, mitigate neuromuscular asymmetries, and optimize readiness for progressive return to loading. From a clinical standpoint, these results position CE as a viable option within individualized rehabilitation protocols, especially in contexts where careful load progression is needed. Similarly, the identified methodological limitations, along with the scarce evidence on neuroplasticity in ACLR populations, underscore the need for future research incorporating direct neurophysiological techniques. Standardizing intervention protocols and assessing CE effects at different postoperative stages would be beneficial. Additionally, expanding the study population to include women, less physically active individuals, and patients with different graft types would improve the clinical applicability of findings. Exploring the long-term impact of CE, as well as its combination with other therapeutic modalities, could represent a promising research avenue in rehabilitation.