Effects of Isometric, Isotonic, and Eccentric VMO Exercises in Patellofemoral Pain Syndrome

Condition(s) studied

Investigational drug(s) / intervention(s)

Isometric VMO Exercise: Isometric contractions of the vastus medialis oblique muscle will be performed with the knee supported at approximately 15° flexion, emphasizing maximal voluntary contraction without joint movement.

Isotonic VMO Exercise: Participants will perform controlled concentric and eccentric contractions using ankle weights through a limited range of motion (0-30° knee extension).

Eccentric VMO Exercise: Participants will perform eccentric contractions against resistance during knee flexion, with assisted concentric return to the starting position.

Study summary

Patellofemoral pain syndrome (PFPS) is a common musculoskeletal condition characterized by anterior knee pain, especially during activities such as stair climbing, squatting, running, and prolonged sitting. Weakness or delayed activation of the vastus medialis oblique (VMO) muscle is considered an important contributing factor in the development of PFPS.

This study aims to compare the effects of three different types of VMO strengthening exercises (isometric, isotonic, and eccentric) applied within the terminal knee extension range (0-30°) on pain, functional performance, and muscle architecture in individuals with PFPS.

Participants will be randomly assigned to one of three exercise groups. All participants will receive a standardized physiotherapy program, including heat therapy, TENS, and therapeutic ultrasound, followed by group-specific VMO strengthening exercises. The intervention will be performed three times per week for 8 weeks.

Outcomes will be assessed before and after the intervention and will include pain intensity (Visual Analog Scale), functional performance (WOMAC, 30-second sit-to-stand test, and stair test), and muscle architecture parameters measured by ultrasound imaging.

The results of this study are expected to provide evidence for optimizing rehabilitation strategies in individuals with PFPS.

Eligibility

Primary outcome measure(s)

• VMO Muscle Architecture (Ultrasound) — Baseline and Week 8
  Muscle thickness, fascicle length, pennation angle, and physiological cross-sectional area of the vastus medialis oblique muscle will be assessed using ultrasound imaging.

Trial sites (1)

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