The Immediate Effects of Instrument-Assisted Soft Tissue Mobilization on Pain and Function in Female Runners with Patellofemoral Pain

<i>Background and Objectives</i>: Patellofemoral pain (PFP) is the most prevalent running-related injury due to underlying biomechanical factors, particularly among female runners. Although instrument-assisted soft tissue mobilization (IASTM) is a popular therapeutic technique, the optimal application site for the short-and long-term outcomes of PFP has not been well established. This aim of this study was to compare the immediate and short-term (1-week) effects of a single IASTM treatment applied to the hip and knee versus the knee alone on running-related pain. Range of motion (ROM), muscle strength, and functional performance were also assessed to compare change between the two treatment conditions. <i>Materials and Methods</i>: Twenty-eight female runners with PFP were randomly assigned to either the Hip and Knee (HK) group (n = 14) or the knee-only (K) group (n = 14). The HK group received a 7-min IASTM treatment targeting the quadriceps, patella, iliotibial band (ITB), and gluteus medius, whereas the K group received a 3-min treatment targeting the quadriceps and patella. Visual analog scale (VAS), hip adduction ROM, hip abduction/external rotation strength, and step-down test scores were measured at baseline, immediately post-intervention, and 1 week later. <i>Results</i>: Running-related pain significantly decreased in both groups (main effect of time, <i>p</i> < 0.001) from baseline (HK: 5.49 ± 2.14 [95% CI: 4.78-6.68]; K: 5.30 ± 1.45 [95% CI: 4.69-5.91]) to week 1 (HK: 1.30 ± 1.08 [95%CI: 0.69-1.90]; K: 1.57 ± 1.20 [95%CI: 0.93-2.21]). However, no significant difference was found between the groups. Significant improvement was also observed in hip adduction ROM (<i>p</i> < 0.001), hip abduction strength (<i>p</i> = 0.02), step-down pain (<i>p</i> < 0.001), and patellofemoral function (<i>p</i> < 0.001) immediately after the intervention, which was sustained at the 1-week follow-up. However, no significant difference was found between the groups. Also, hip external rotation strength showed no significant change over time or between groups (<i>p</i> = 0.737). <i>Conclusions</i>: A single IASTM session effectively reduced pain and improved function in female runners with PFP. However, the hip treatment did not show a significant additional benefit compared with knee treatment alone. IASTM can provide immediate and short-term relief of pain and functional limitations.