# Acute Effects of Static Stretching on Submaximal Force Control of the Ankle
## 4 Discussion  
This study aimed to investigate the acute effects of SS of the plantar flexors on force control during a dynamic force-tracking task. Notably, the force-tracking performance, as assessed by the RMSE, did not significantly change in the low-range task, but showed a significant improvement in the high-range task, particularly during the force release phase. These findings provide novel evidence that the effects of SS on neuromuscular performance may vary depending on the intensity and phase-specific demands of the task. In addition, SS led to a significant increase in ankle dorsiflexion range of motion and a decrease in musculotendinous stiffness, consistent with previous reports [5, 29]. The high-range task, which requires participants to produce a larger absolute torque within the same relative range (40-60% MVIC), likely imposes greater neuromuscular demands compared to the low-range task. Specifically, the need for precise control over higher force levels may render the task more sensitive to subtle neuromechanical changes induced by the SS. Among the two force phases, the release phase appears to be particularly demanding, as it requires rapid and smooth downregulation of muscular activity, a process that is generally more difficult to control than force generation [21]. In contrast, the generation phase primarily involves straightforward force production, which may be less influenced by small changes in neuromuscular function. Taken together, the refinement observed specifically in the release phase of the high-range task suggests that this condition effectively captured acute neuromuscular changes induced by SS. Although previous studies have consistently reported impaired force steadiness following SS during isometric tasks with constant force demands [24, 25], the current results demonstrate a contrasting enhancement in isometric tasks involving dynamic force modulation, particularly during the high-range release phase. A key factor that may explain this discrepancy is the nature of force control required for each task. Traditional steadiness assessments involve maintaining a fixed level of force output, which emphasizes stability. In contrast, the force-tracking task used in this study required participants to continuously adjust their force to match a time-varying target, engaging different aspects of neuromuscular control, particularly those related to fine-tuned modulation over time. Furthermore, the stretching duration may also contribute to divergent outcomes. Studies reporting negative effects often employed longer SS protocols (e.g., five sets of 60 s), which may have induced neuromuscular inhibition, characterized by decreased excitability of muscle spindles and \(\alpha\)-motoneuron, as well as suppressed central pathways, which led to reduced spinal excitability revealed by attenuated H-reflex responses [34, 35, 36, 37], and reduced force transmission efficiency due to increased compliance of the muscle-tendon unit [38]. In contrast, the present study used a single 60 s stretch, which may have been sufficient to reduce mechanical resistance and promote smoother movement without eliciting inhibitory neural responses [39]. Recent findings also suggest that 4 \(\times\) 30 s SS can suppress unnecessary co-contraction without compromising the force-generating capacity [40]. The