Acute Effects of Static and Proprioceptive Neuromuscular Facilitation Stretching on the Ankle's Range of Motion and...

Objectives: The primary aim of this study was to compare the acute effects of two stretching techniques-static stretching (SST) and proprioceptive neuromuscular facilitation (PNF)-on functional outcomes related to postural balance (stabilographic parameters) and ankle range of motion (ROM; active and passive measures). Furthermore, the study aimed to assess the association between changes in balance- and ROM-related parameters. Methods: The study sample consisted of 24 young adults in the age range of 21-24. The SS group (n = 12) mean body height was 174.3 ± 7.8 [cm], body weight 68.0 ± 13.1 [kg], and BMI 22.2 ± 2.8 [kg/m²]. The PNF group's (n = 12) mean body height was 173.7 ± 7.3 [cm], body weight 68.6 ± 13.5 [kg], and BMI 22.5 ± 3.0 [kg/m²]. The subjects performed static stretching or proprioceptive neuromuscular facilitation stretching involving the tibialis anterior, gastrocnemius, and soleus muscles. Before and immediately after the intervention, the active and passive range of plantar and dorsal flexion of the foot and the stability of the body posture in the anterior-posterior plane were measured based on the analysis of the center of pressure (COP) sway. Results: The results of the mixed model ANOVA (intervention × time) showed no statistically significant effect of the intervention or interaction between intervention and time for ROM and COP measurements. In both cases, a statistically significant time effect was found. After intervention, significant differences were found in COP variability (p = 0.02), COP range (p = 0.03), fractal dimension (p = 0.04), and sample entropy (p = 0.01). Similarly, for range of motion, differences were observed in passive dorsiflexion (p < 0.01), active plantarflexion (p < 0.01), and passive plantarflexion (p = 0.01). Pearson's correlation analysis did not reveal significant associations between changes in ankle range of motion and COP variables. Conclusions: The results of this study indicate that both static and PNF stretching acutely increase the range of motion in the ankle joint; however, they also lead to a decrease in postural stability under more challenging conditions involving visual or vestibular deprivation. The magnitude of the range of motion changes was not associated with alterations in stabilographic parameters.