Patellar Tendinopathy / Jumpers Knee

The goal of this clinical trial is to evaluate whether a long-hold yielding isometric exercise program improves pain, tendon vascularity, mechanical properties, and functional performance in weightlifting athletes with patellar tendinopathy. The study will also explore the safety and feasibility of this exercise strategy. Researchers will compare the long-hold isometric intervention with routine training recommendations to determine its effects on symptoms and tendon function. Participants will perform the supervised isometric protocol and complete pain ratings, functional tests, and ultrasound evaluations of the patellar tendon.

This study investigates the immediate effects of different peripheral electrical nerve stimulation protocols applied to the femoral nerve on quadriceps strength in athletes with patellar tendinopathy. Patellar tendinopathy is a common overuse injury that often reduces quadriceps activation and limits sports performance. Peripheral percutaneous nerve stimulation (PPNS) and transcutaneous electrical nerve stimulation (TENS) are frequently used in rehabilitation, but their frequency-dependent effects on muscle strength are not well established. In this randomized crossover trial, each participant receives three stimulation protocols in separate sessions: high-frequency PPNS (100 Hz), low-frequency PPNS (2 Hz), and conventional TENS. All stimulation is delivered at the maximal tolerated motor threshold and, for PPNS conditions, under ultrasound guidance. Quadriceps maximal isometric strength is evaluated using an isometric force sensor before and after each intervention. The primary objective is to compare the acute changes in maximal voluntary contraction (MVC) following each stimulation protocol. The study aims to clarify whether different stimulation frequencies can enhance, reduce, or have no effect on quadriceps strength in this athletic population. By identifying frequency-specific neuromodulatory responses, this study may help clinicians and sports practitioners select the most appropriate stimulation parameters to optimize rehabilitation and performance in individuals with patellar tendinopathy.