Frequency-Dependent Effects of Percutaneous Femoral Nerve Stimulation on Quadriceps Strength in Athletes With Patellar Tendinopathy (ppns)

Frequency-Dependent Effects of Percutaneous Femoral Nerve Stimulation on Strength in Athletes With Patellar Tendinopathy: a Randomized Controlled Trial

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.

Study Overview

• Status: Recruiting
• Conditions: Patellar Tendinopathy / Jumpers Knee
• Intervention / Treatment: Device: Electrical stimulation

• Study Type: Interventional
• Enrollment (Estimated): 19
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Javier Picañol Parraga Picañol, Phd; Phone Number: +34655394127; Email: xpicanol@ub.edu

Study Locations

• Spain
  • Barcelona
    • Barcelona, Barcelona, Spain, 08020
      • Recruiting
      • Blanquerna University
      • Contact: Francesco Sartori, Phd; Phone Number: 663583945; Email: sartorifrancesco99@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults aged 18 to 40 years.
• Recreational or competitive athletes with clinically diagnosed patellar tendinopathy for at least 3 months.
• Ultrasound-confirmed patellar tendinopathy, including hypoechoic areas, tendon thickening, or neovascularization consistent with clinical diagnosis.

Presence of pain during tendon-loading activities (e.g., jumping, running, squatting).

• Ability to perform maximal voluntary isometric contractions of the quadriceps.
• Ability to comply with all study procedures and attend all experimental sessions.
• Written informed consent obtained prior to participation.

Exclusion Criteria:

• Previous knee surgery or traumatic knee injury within the past 12 months.
• Complete or partial patellar tendon rupture.
• Neurological disorders affecting lower limb strength or motor control.
• Contraindications to electrical stimulation, including implanted electrical devices (e.g., pacemaker).
• Current lower-limb radiculopathy or neuropathy.
• Skin infections, open wounds, or dermatological conditions at the stimulation site.
• Use of analgesics, anti-inflammatories, or corticosteroid injections within the past 48 hours.
• Participation in another interventional study in the previous 30 days.
• Pregnancy or suspected pregnancy.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Transcutaneous Electrical Nerve Stimulation (TENS); Participants receive conventional transcutaneous electrical nerve stimulation (TENS) applied over the femoral nerve region using surface electrodes. Intensity is set at the maximal tolerated motor threshold to elicit visible quadriceps activation. The stimulation frequency and parameters are consistent with standard clinical practice for motor-level TENS.	Device: Electrical stimulation; All electrical stimulation procedures are performed under real-time ultrasound guidance to accurately locate the femoral nerve and ensure safe and consistent electrode placement. For the percutaneous interventions (PPNS), a sterile needle electrode is inserted adjacent to the femoral nerve and stimulation is delivered at either high frequency (100 Hz) or low frequency (2 Hz), depending on the study arm. For the transcutaneous intervention (TENS), surface electrodes are positioned over the femoral nerve region using ultrasound guidance to confirm anatomical landmarks and optimize current delivery. In all conditions, stimulation is applied at the maximal tolerated motor threshold to elicit visible quadriceps activation.; Other Names: Ultrasound-guided electrical stimulation
Experimental: High-Frequency PPNS (100 Hz); Participants receive peripheral percutaneous nerve stimulation (PPNS) applied to the femoral nerve at 100 Hz.	Device: Electrical stimulation; All electrical stimulation procedures are performed under real-time ultrasound guidance to accurately locate the femoral nerve and ensure safe and consistent electrode placement. For the percutaneous interventions (PPNS), a sterile needle electrode is inserted adjacent to the femoral nerve and stimulation is delivered at either high frequency (100 Hz) or low frequency (2 Hz), depending on the study arm. For the transcutaneous intervention (TENS), surface electrodes are positioned over the femoral nerve region using ultrasound guidance to confirm anatomical landmarks and optimize current delivery. In all conditions, stimulation is applied at the maximal tolerated motor threshold to elicit visible quadriceps activation.; Other Names: Ultrasound-guided electrical stimulation
Experimental: Low-Frequency PPNS (2 Hz); Participants receive peripheral percutaneous nerve stimulation (PPNS) applied to the femoral nerve at 2 Hz.	Device: Electrical stimulation; All electrical stimulation procedures are performed under real-time ultrasound guidance to accurately locate the femoral nerve and ensure safe and consistent electrode placement. For the percutaneous interventions (PPNS), a sterile needle electrode is inserted adjacent to the femoral nerve and stimulation is delivered at either high frequency (100 Hz) or low frequency (2 Hz), depending on the study arm. For the transcutaneous intervention (TENS), surface electrodes are positioned over the femoral nerve region using ultrasound guidance to confirm anatomical landmarks and optimize current delivery. In all conditions, stimulation is applied at the maximal tolerated motor threshold to elicit visible quadriceps activation.; Other Names: Ultrasound-guided electrical stimulation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Quadriceps Maximal Isometric Voluntary Contraction (MVC)	Quadriceps maximal isometric voluntary contraction (MVC) is measured using a calibrated isometric force sensor with the participant seated and the knee positioned at 60° of flexion. MVC is recorded as the peak force output during a standardized 5-second maximal contraction. The primary endpoint is the change in MVC from pre-intervention to immediately post-intervention across the three stimulation conditions (high-frequency PPNS, low-frequency PPNS, and TENS). Higher values indicate greater quadriceps force production.	Baseline (pre-intervention), and at 2 minutes, 10 minutes, 15 minutes, and 30 minutes post-intervention.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Quadriceps Rate of Force Development (RFD 0-250 ms)	Quadriceps rate of force development (RFD) in the early phase of contraction (0-250 ms) is calculated from the force-time curve obtained during maximal isometric voluntary contractions using a calibrated isometric force sensor. RFD 0-250 ms reflects the participant's ability to rapidly generate force and is derived as the slope of the force increase within the first 250 milliseconds. The outcome measure is the change in RFD between baseline and the post-intervention time points across the three stimulation conditions (high-frequency PPNS, low-frequency PPNS, and TENS).	Baseline (pre-intervention), and at 2 minutes, 10 minutes, 15 minutes, and 30 minutes post-intervention.
Change in Quadriceps Impulse (0-250 ms)	Quadriceps impulse (0-250 ms) is calculated as the integrated area under the force-time curve during the first 250 milliseconds of a maximal isometric voluntary contraction, recorded using a calibrated isometric force sensor. This metric reflects the combined ability to rapidly generate and sustain force during the early phase of contraction. The outcome measure is the change in impulse between baseline and post-intervention assessments across the three stimulation conditions (high-frequency PPNS, low-frequency PPNS, and TENS).	Baseline (pre-intervention), and at 2 minutes, 10 minutes, 15 minutes, and 30 minutes post-intervention.
Incidence of Adverse Events Assessed Through Post-Intervention Questionnaires	Adverse events related to the stimulation procedures are assessed using a standardized post-intervention questionnaire completed immediately after each stimulation session. Participants are asked to report the presence and severity of any undesirable effects, including discomfort, pain, bleeding, bruising, transient paresthesia, dizziness, or any unexpected symptoms. All adverse events are recorded, categorized by type and severity, and evaluated for their potential relationship to the intervention (high-frequency PPNS, low-frequency PPNS, or TENS). No serious adverse events are anticipated due to the low-risk nature of the procedures.	Immediately after each intervention session.

Collaborators and Investigators

• Sponsor: Hospital Clinic of Barcelona

Study record dates

Study Major Dates

• Study Start (Actual): September 20, 2025
• Primary Completion (Estimated): November 30, 2025
• Study Completion (Estimated): December 15, 2025

Study Registration Dates

• First Submitted: November 15, 2025
• First Submitted That Met QC Criteria: November 15, 2025
• First Posted (Estimated): November 20, 2025

Study Record Updates

• Last Update Posted (Actual): December 5, 2025
• Last Update Submitted That Met QC Criteria: November 29, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: Transcutaneous Electrical Nerve Stimulation; Peripheral Percutaneous Nerve Stimulation
• Additional Relevant MeSH Terms: Investigative Techniques; Physical Stimulation; Electric Stimulation
• Other Study ID Numbers: 2025-04-05

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

IPD Plan Description

No final decision has yet been made regarding the sharing of de-identified individual participant data (IPD) from this study. Data sharing may be considered after publication of the study results and pending compliance with ethical approvals, institutional policies, and participant confidentiality protections. Only fully de-identified datasets would be eligible for potential sharing.

Access Criteria and How to Request IPD

If data sharing is approved in the future, de-identified IPD will be made available to qualified researchers upon reasonable request. Interested investigators may contact the Principal Investigator with a methodologically sound proposal. Access will be granted only after review of the request and signature of a data use agreement.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No