## 4 Discussion
Among the mechanisms proposed to explain these results is neuromuscular compartmentalization, where each gastrocnemius head has its own moment arms and length tension curves during ankle movements [7; 54; 55]. These findings support our first hypothesis: the MG and LG exhibit different activation profiles between unilateral and bilateral HREs but respond similarly to ROM changes. Our results support the role of muscle length in promoting longitudinal growth [53]. Although EMG differences across the ROM cannot predict morphological adaptations, they offer initial evidence to guide gastrocnemius exercise selection. Unlike our findings, [PERSON] et al. [26] reported similar MG and LG activation during standing HREs at 0\({}^{\circ}\) and 45\({}^{\circ}\) knee flexion. This may be due to reduced gastrocnemius tension when the knee is flexed, shifting mechanical advantage to the soleus [56]. Thus, increasing muscle length via ankle dorsiflexion more effectively enhances MG and LG activation than altering the knee angle. Comparison with previous studies is limited, as most focused on the knee rather than the ankle angle. Similarly, [PERSON] et al. [26] found no MG:LG activation differences when modifying the ROM during standing HREs at 0\({}^{\circ}\) and 45\({}^{\circ}\) knee flexion. In contrast, other studies reported greater MG activation with lower knee angles, while the LG remained uncharged [23; 24; 25]. These findings, derived from non-weight-bearing, open-chain tasks with isometric EMG normalization, limit generalizability to standard weight-bearing HREs. Further research is needed to clarify whether increased ankle dorsiflexion alters MG:LG activation patterns. Still, our findings support using an extended ROM in HREs to enhance gastrocnemius activation, in line with evidence favoring training at longer muscle lengths [24; 27; 28]. The LG showed greater activation in unilateral than bilateral exercises, unlike the MG. This may be due to the full-body-weight support, reduced base of support, and greater neuromuscular demands in unilateral tasks [55]. Additionally, the LG's lower passive stiffness and smaller volume compared to the MG [53; 54] may make it more responsive to these demands. This effect was not observed in the non-dominant leg, suggesting inter-limb asymmetries [57]. However, activation alone does not clarify whether differences are due to strength or neuromuscular control. Given the ankle's key role in functional tasks and the link between leg dominance and lower-limb injury risk [58], future studies should explore whether these asymmetries contribute to injury susceptibility. Regarding leg dominance, MG EMG activity was unaffected by any HRE condition. This finding is relevant for two reasons. First, it provides normative data for unilateral and bilateral weight-bearing HREs, supporting its application as a clinical screening tool to assess muscle and soft tissue recovery. Second, it suggests that MG EMG data from the dominant leg during unilateral FROM HREs should not be extrapolated to the non-dominant leg. The trend toward greater MG activation in the non-dominant limb observed in our study requires cautious interpretation. This finding may reflect a stabilization bias, as the non-preferred leg often acts as the support limb during unilateral tasks, potentially demanding enhanced postural control and neuromuscular recruitment. Alternatively, this asymmetry could stem from individual motor strategies or sampling variability inherent in small cohorts (\(n=19\)). While previous studies have shown variable inter-limb EMG patterns during balance-related and functional activities [59], the observed trend in MG activation emphasizes the need for future research exploring neuromechanical roles of the support leg in loaded plantar flexion tasks. Our second hypothesis was not supported, as MG:LG activation ratios did not differ significantly by ROM or exercise type. Only the unilateral FROM HRE, the most demanding condition, showed a distinct MG:LG ratio. [PERSON] et al.