This randomized, double-blind, controlled trial aims to investigate the acute effects of therapeutic ultrasound applied to the patellar tendon on vertical jump performance in healthy university students. Therapeutic ultrasound is widely used in physiotherapy to influence soft tissue properties through thermal and mechanical effects; however, its immediate impact on explosive lower-extremity performance and neuromuscular function remains unclear.

Participants will be randomly assigned to either a therapeutic ultrasound group or a sham ultrasound (placebo) group. In the intervention group, therapeutic ultrasound will be applied to the patellar tendon using a frequency of 1 MHz and an intensity of 1.5 W/cm² in continuous mode for 5 minutes. In the control group, a sham ultrasound procedure will be performed using the same device and duration without delivering therapeutic energy. Both the participants and the outcome assessor will be blinded to group allocation.

Vertical jump performance will be evaluated using the countermovement jump (CMJ) test recorded with the My Jump 2 smartphone application. In addition, quadriceps muscle strength will be measured using a hand-held dynamometer, and knee joint position sense will be assessed using a joint position reproduction test. All measurements will be conducted before and immediately after the intervention.

This study will provide evidence regarding whether therapeutic ultrasound applied to the patellar tendon can acutely influence explosive performance, muscle strength, and proprioception in healthy individuals.

This randomized, double-blind, controlled trial aims to investigate the acute effects of therapeutic ultrasound applied to the patellar tendon on vertical jump performance, quadriceps muscle strength, and knee joint proprioception in healthy university students. Therapeutic ultrasound is a commonly used physiotherapy intervention that can induce thermal and mechanical effects on soft tissues; however, its immediate impact on explosive lower-extremity performance and neuromuscular function has not been fully established.

A total of healthy participants aged 18-35 years will be recruited and screened according to predefined inclusion and exclusion criteria. Eligible participants will be randomly assigned to either a therapeutic ultrasound group or a sham (placebo) ultrasound group. The intervention group will receive therapeutic ultrasound applied to the patellar tendon at a frequency of 1 MHz, intensity of 1.5 W/cm², in continuous mode for 5 minutes. The sham group will undergo the same procedure without delivery of therapeutic energy. Both participants and the outcome assessor will be blinded to group allocation, ensuring a double-blind design.

Outcome measures will be recorded immediately before and within one minute after the intervention. Vertical jump performance will be assessed using the countermovement jump (CMJ) recorded with the My Jump 2 smartphone application. Quadriceps muscle strength will be measured using a hand-held dynamometer, and knee joint position sense will be evaluated using a joint position reproduction test. Participants will perform three trials for each measure, with 60-second rest intervals between trials, and the best value will be used for analysis. Familiarization trials will be conducted prior to testing to minimize learning effects.

This study will provide evidence on whether therapeutic ultrasound applied to the patellar tendon can acutely influence explosive performance, quadriceps strength, and proprioception in healthy individuals, which may inform clinical and sports performance applications.

Inclusion Criteria:

• Healthy university students aged 18-35 years
• No history of lower extremity injury or surgery in the past 12 months
• No current musculoskeletal or neurological disorders affecting the lower limbs

Exclusion Criteria:

• History of patellar tendon injury or knee pain
• Contraindications to therapeutic ultrasound (e.g., skin lesions, open wounds at the knee, or implanted electronic devices)
• Any cardiovascular, neurological, or musculoskeletal condition that may affect jump performance
• Use of medications that could affect neuromuscular function (e.g., muscle relaxants)