Acute Effects of Different Triceps Surae Stretching Modalities on Post-Sit-to-Stand Postural Control in Healthy Young Adults: An Exploratory Pre–Post Pilot Study

Abstract

Ankle postural control is essential for standing stability immediately after sit-to-stand (STS), a movement associated with falls in older adults. Although triceps surae stretching is commonly used before exercise, its immediate effects on post-STS postural sway remain unclear. This exploratory study investigated the effects of static (SS), dynamic (DS), and ballistic stretching (BS) on post-STS postural sway and directional shifts in the anteroposterior extremes of center-of-pressure (CoP) after STS in a repeated-measures design with 10 healthy young adults (8 males, 2 females, mean ± SD age: 20.1 ± 0.3 years, age range 20–21 years). On three separate days, participants performed STS at a same-day pre-stretching baseline and after one of the stretching modalities. A force plate measured CoP in the anteroposterior direction (CoPap) during 0–10, 0–3, and 3–10 s after standing, and the standard deviation of CoPap was calculated as an index of post-STS postural sway. For the primary outcome measure (0–3 s), directional shifts in the anteroposterior extremes of CoPap during the first trial were assessed based on the change in the anterior and posterior positions of CoPap from the pre-stretching baseline to the post-stretching condition. Two-factor repeated-measures ANOVA revealed no significant main effects or interactions across all time intervals (all p ≥ 0.187). For the primary outcome—the 0–3-s interval—no significant effects were observed for stretch modality (F(2, 18) = 1.177, p = 0.331, partial η2 = 0.116), trial (F(2, 18) = 0.314, p = 0.735, partial η2 = 0.034), or their interaction (Greenhouse–Geisser-corrected F(1.75, 15.72) = 1.170, p = 0.329, partial η2 = 0.115). Directional shifts in CoPap extremes showed 95% confidence intervals crossing zero across all modalities, with modest mean changes (<3%FL) and substantial inter-individual variability. In conclusion, acute triceps surae stretching did not significantly alter post-STS postural sway variability in this sample of healthy young adults, while preliminary descriptive findings highlight the importance of considering individual variability and directional CoP behavior in dynamic stability assessments.