Effect of plantar fascia-specific stretching and Achilles tendon stretching on shear wave elasticity of the plantar fascia in healthy subjects

The effect of stretching on the mechanical properties of the plantar fascia (PF) remain unclear. This study was performed to determine the effect of PF-specific stretching (PFSS) and Achilles tendon stretching (ATS) on the viscoelastic properties of the PF with shear wave elastography (SWE).We recruited 14 participants (8 men, 6 women) with no history of PF disorders or painful episodes. The mean age of the participants was 30.9 ± 4.8 (range, 25-41) years. All participants performed sustained PFSS (sPFSS) on one foot and intermittent PFSS (iPFSS) on the other foot. Two weeks later, all participants performed sustained ATS (sATS) on one foot and intermittent ATS (iATS) on the other foot. SWE measurements were performed immediately after each stretching.The PF elasticity immediately before stretching ranged from 133.8 kPa to 144.7 kPa. The PF elasticity after stretching ranged from 158.9 kPa to 215.8 kPa. There was a significant increase in PF elasticity after sPFSS, iPFSS, sATS, and iATS (P < .01). The elasticity after sATS was greater than that after iATS (P = .03). In contrast, there were no differences in PF elasticity after stretching between sPFSS and iPFSS (P = .13), sPFSS and sATS (P = .17), or iPFSS and iATS (P = .50).PF elasticity increased after stretching regardless of the frequency and type of PFSS and ATS.Level II, prospective cohort study.