Achilles Tendinopathy (AT)NCT07453485
Immediate Effects of Neuromuscular Electrical Stimulation on Pain and Function in Achilles Tendon Disorders
A study testing Neuromuscular Electrical Stimulation (NMES) in people with Achilles Tendinopathy (AT) and Achilles Tendon Rupture, run by University of Brasilia at 1 site in Brazil.
Trial summary
The Achilles tendon exhibits high tensile strength and can withstand extremely high loads. However, it is susceptible to injuries such as tendinopathies and ruptures, which are associated with structural alterations and loss of function. Strategies have been investigated to enhance clinical rehabilitation. Read more about this study
- Who is it for?
- Ages 18 to 60 years
- Conditions the study is for
- Achilles Tendinopathy (AT), Achilles Tendon Rupture
- What is being tested?
- Neuromuscular Electrical Stimulation (NMES)
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 30 participants
- Where
- 1 siteBrazil
- Study dates
- 6 Jan 2026to 30 Dec 2029
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 60 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Primary complaint of pain localized in the midportion (2-6 cm proximal to the calcaneus) or insertion of the Achilles tendon, and/or a history of Achilles tendon rupture occurring at least 3 months prior to assessment.
- Pain on palpation of the Achilles tendon.
- Pain during load-bearing activities
Who cannot join
- Exclusive diagnosis of bursitis confirmed by ultrasonographic assessment
- Any other lower limb injury
- History of lower limb surgery within the past year
- Previous Achilles tendon tenoplasty performed less than 3 months prior to assessment
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Brazil1 site, 1 recruiting
- Recruiting
University of Brasilia
Brasília, Federal District, 72220900
João LQ Durigan, PhD, +55 61 3107-8450, joaodurigan@gmail.com
José RS Júnior, PhD, +55 61 3107-8450, joserobertofisio@gmail.com
About this study
Official title: Immediate Effects of Neuromuscular Electrical Stimulation on Pain and Functional Performance in Individuals With Achilles Tendinopathy and Tendon Rupture: A Randomized Crossover Clinical Trial
The Achilles tendon exhibits high tensile strength and can withstand extremely high loads. However, it is susceptible to injuries such as tendinopathies and ruptures, which are associated with structural alterations and loss of function. Strategies have been investigated to enhance clinical rehabilitation. Nevertheless, the effects of neuromuscular electrical stimulation on pain and functional improvement, as well as the optimal dosing parameters for the rehabilitation of Achilles tendon injuries, remain inconclusive. The aim of this study is to compare the immediate effects of two electrical stimulation protocols on pain, functional performance, peripheral oxygen extraction, and maximal tendon displacement during a single leg heel rise functional task in patients with Achilles tendinopathy and/or a history of Achilles tendon rupture. In addition, this study aims to characterize Achilles tendon structural properties and ankle plantarflexor muscle strength in this population.
Read the detailed description
All groups will be composed of participants with a primary complaint of pain and/or a history of previous Achilles tendon rupture. Participants will perform the interventions in two blocks separated by a seven-day interval (wash-out). Block A: (1) control without active intervention and (2) electrical stimulation applied at the maximum tolerated intensity. Block B: (3) control with sham stimulation and (4) sensory-level electrical stimulation. Block A will always be performed first, followed by Block B. Interventions within each block will be conducted in three sets of 10 repetitions, totaling six sets per day.
- Being tested
- Neuromuscular Electrical Stimulation (NMES)
- Keywords
- Achilles tendon, Achilles tendinopathy, Achilles tendon rupture, Neuromuscular electrical stimulation, Pain, Functional performance
- Medical subject headings
- Pain
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Neuromuscular Electrical Stimulation (NMES)Device
Neuromuscular electrical stimulation-induced contractions will be delivered using an electrical stimulator connected to a pair of 5×5 cm self-adhesive surface electrodes. Stimulation will be applied in a superimposed manner during voluntary movement, at a frequency of 75 Hz and a phase duration of 400 µs.
| Study group | Role | What they receive |
|---|---|---|
| Control without active intervention | No intervention | In this group, participants will perform three sets of 10 repetitions of the single leg heel rise functional task without the application of electrical stimulation. Immediately after each set, pain level, functional performance, peripheral oxygen extraction, and maximal Achilles tendon displacement will be assessed. |
| Electrical stimulation applied at the maximum tolerated intensity | Experimental | Under this condition, participants will perform three sets of 10 repetitions of the single leg heel rise functional task with superimposed electrical stimulation applied at the maximum tolerated intensity, characterized by visible muscle contraction and associated with a self-reported discomfort level between 8 and 10 on the Numeric Rating Scale. Immediately after each set, pain level, functional performance, peripheral oxygen extraction, and maximal Achilles tendon displacement will be assessed. Receives: Device: Neuromuscular Electrical Stimulation (NMES) |
| Control with sham stimulation | Placebo comparator | For this condition, participants will perform three sets of 10 repetitions of the single leg heel rise functional task with superimposed sham electrical stimulation. Electrical stimulation parameters will initially be configured identically to those used in the active intervention. However, to ensure adequate blinding, stimulation will be applied for approximately 40 seconds and then gradually reduced until complete cessation. From this point onward, no additional current will be delivered, although the device will remain on and the electrodes will remain in place throughout the test. Immediately after each set, pain level, functional performance, peripheral oxygen extraction, and maximal Achilles tendon displacement will be assessed. Receives: Device: Neuromuscular Electrical Stimulation (NMES) |
| Sensory-level electrical stimulation | Active comparator | In this condition, participants will perform three sets of 10 repetitions of the single leg heel rise functional task with superimposed electrical stimulation applied at the sensory level, defined as the highest intensity that does not elicit visible muscle contraction. Immediately after each set, pain level, functional performance, peripheral oxygen extraction, and maximal Achilles tendon displacement will be assessed. Receives: Device: Neuromuscular Electrical Stimulation (NMES) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Pain level
Pain intensity during the single leg heel rise task will be assessed using the Visual Analog Scale, consisting of a numerical scale ranging from 0 to 10 points, in which 0 represents no pain and 10 corresponds to the worst pain ever experienced by the participant.
Measured: Immediately after the performance of the functional task
Secondary outcomes (15)
Total time
The total time (s) during the single-leg heel rise task will be measured using the MuscleLab® system.
Measured: Immediately after the performance of the functional task.
Maximal displacement
The maximal displacement (cm) during the single-leg heel rise task will be measured using the MuscleLab® system.
Measured: Immediately after the performance of the functional task.
Total work
The total work (J) during the single-leg heel rise task will be measured using the MuscleLab® system.
Measured: Immediately after the performance of the functional task.
Total power
The total power (W) during the single-leg heel rise task will be measured using the MuscleLab® system.
Measured: Immediately after the performance of the functional task.
Number of repetitions
The number of repetitions completed during the single-leg heel rise task will be recorded using the MuscleLab® system.
Measured: Immediately after the performance of the functional task.
Peripheral oxygen extraction
Oxygen extraction of the periarticular ankle muscles will be assessed using near-infrared spectroscopy, with the sensor positioned on the skin over the lateral gastrocnemius muscle during the single leg heel rise task. Variations in oxy- and deoxy-hemo/myoglobin (O₂Hb and HHb, respectively) will be recorded in arbitrary units at a sampling frequency of 25 Hz.
Measured: Immediately after the performance of the functional task.
Maximal Achilles tendon displacement
Maximal Achilles tendon displacement (%) will be measured using a transducer positioned over the myotendinous junction of the gastrocnemius muscles, secured to a specific support, during the single leg heel rise task. Maximal displacement will be determined based on the change in Achilles tendon length relative to its resting length.
Measured: Immediately after the performance of the functional task.
Lenght of achilles tendon
The total and free length (cm) of the Achilles tendon will be measured using portable ultrasonography.
Measured: Baseline (prior to Block A only)
Thickness of achilles tendon
The thickness (mm) of the Achilles tendon will be measured using portable ultrasonography.
Measured: Baseline (prior to Block A only)
Cross-sectional area of achilles tendon
The cross-sectional area (cm²) of the Achilles tendon will be measured using portable ultrasonography.
Measured: Baseline (prior to Block A only)
Presence of neovascularization of the Achilles tendon
The presence of neovascularization of the Achilles tendon will be assessed using portable ultrasonography.
Measured: Baseline (prior to Block A only)
Elastic modulus
The median elastic modulus (kPa) of the Achilles tendon will be measured using shear wave elastography.
Measured: Baseline (prior to Block A only)
Shear wave velocity
The median shear wave velocity (m/s) of the Achilles tendon will be measured using shear wave elastography.
Measured: Baseline (prior to Block A only)
Depth
The measurement depth (cm) of the Achilles tendon during elastography assessment will be recorded using shear wave elastography.
Measured: Baseline (prior to Block A only)
Isometric strength
Isometric strength will be assessed using an isokinetic dynamometer, based on peak isometric torque (N/m) during plantar flexion at 0°.
Measured: Baseline (prior to Block A only)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Mar 2026
- Study start6 Jan 2026
- Primary completion30 Aug 2029 (estimated)
- Study completion30 Dec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Achilles Tendinopathy (AT)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Brasilia
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07453485
- Sponsor's protocol ID
- CAAE: 94397825.9.0000.8093
- Status last verified
- Mar 2026
- First submitted
- 13 Feb 2026
- Last updated
- 6 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 6 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Immediate Effects of Neuromuscular Electrical Stimulation on Pain and Functional Performance in Individuals With Achilles Tendinopathy and Tendon Rupture: A Randomized Crossover Clinical Trial
- ClinicalTrials.gov ID
- NCT07453485
- Acronym / sponsor ID
- CAAE: 94397825.9.0000.8093
- Keywords
- Achilles tendon, Achilles tendinopathy, Achilles tendon rupture, Neuromuscular electrical stimulation, Pain, Functional performance
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- University of BrasiliaUniversity, hospital or other
- Study start
- 6 Jan 2026 (actual)
- Primary completion
- 30 Aug 2029 (estimated)
- Study completion
- 30 Dec 2029 (estimated)
- First posted
- 6 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The Achilles tendon exhibits high tensile strength and can withstand extremely high loads. However, it is susceptible to injuries such as tendinopathies and ruptures, which are associated with structural alterations and loss of function. Strategies have been investigated to enhance clinical rehabilitation. Nevertheless, the effects of neuromuscular electrical stimulation on pain and functional improvement, as well as the optimal dosing parameters for the rehabilitation of Achilles tendon injuries, remain inconclusive. The aim of this study is to compare the immediate effects of two electrical stimulation protocols on pain, functional performance, peripheral oxygen extraction, and maximal tendon displacement during a single leg heel rise functional task in patients with Achilles tendinopathy and/or a history of Achilles tendon rupture. In addition, this study aims to characterize Achilles tendon structural properties and ankle plantarflexor muscle strength in this population.
Detailed description
All groups will be composed of participants with a primary complaint of pain and/or a history of previous Achilles tendon rupture. Participants will perform the interventions in two blocks separated by a seven-day interval (wash-out). Block A: (1) control without active intervention and (2) electrical stimulation applied at the maximum tolerated intensity. Block B: (3) control with sham stimulation and (4) sensory-level electrical stimulation. Block A will always be performed first, followed by Block B. Interventions within each block will be conducted in three sets of 10 repetitions, totaling six sets per day.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (participant)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Control without active intervention | No intervention | –In this group, participants will perform three sets of 10 repetitions of the single leg heel rise functional task without the application of electrical stimulation. Immediately after each set, pain level, functional performance, peripheral oxygen extraction, and maximal Achilles tendon displacement will be assessed. |
| Electrical stimulation applied at the maximum tolerated intensity | Experimental | Device: Neuromuscular Electrical Stimulation (NMES)Under this condition, participants will perform three sets of 10 repetitions of the single leg heel rise functional task with superimposed electrical stimulation applied at the maximum tolerated intensity, characterized by visible muscle contraction and associated with a self-reported discomfort level between 8 and 10 on the Numeric Rating Scale. Immediately after each set, pain level, functional performance, peripheral oxygen extraction, and maximal Achilles tendon displacement will be assessed. |
| Control with sham stimulation | Placebo comparator | Device: Neuromuscular Electrical Stimulation (NMES)For this condition, participants will perform three sets of 10 repetitions of the single leg heel rise functional task with superimposed sham electrical stimulation. Electrical stimulation parameters will initially be configured identically to those used in the active intervention. However, to ensure adequate blinding, stimulation will be applied for approximately 40 seconds and then gradually reduced until complete cessation. From this point onward, no additional current will be delivered, although the device will remain on and the electrodes will remain in place throughout the test. Immediately after each set, pain level, functional performance, peripheral oxygen extraction, and maximal Achilles tendon displacement will be assessed. |
| Sensory-level electrical stimulation | Active comparator | Device: Neuromuscular Electrical Stimulation (NMES)In this condition, participants will perform three sets of 10 repetitions of the single leg heel rise functional task with superimposed electrical stimulation applied at the sensory level, defined as the highest intensity that does not elicit visible muscle contraction. Immediately after each set, pain level, functional performance, peripheral oxygen extraction, and maximal Achilles tendon displacement will be assessed. |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Primary complaint of pain localized in the midportion (2-6 cm proximal to the calcaneus) or insertion of the Achilles tendon, and/or a history of Achilles tendon rupture occurring at least 3 months prior to assessment.
- Pain on palpation of the Achilles tendon.
- Pain during load-bearing activities
Key exclusion criteria (4 listed)
- Exclusive diagnosis of bursitis confirmed by ultrasonographic assessment
- Any other lower limb injury
- History of lower limb surgery within the past year
- Previous Achilles tendon tenoplasty performed less than 3 months prior to assessment
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Neuromuscular Electrical Stimulation (NMES)Neuromuscular electrical stimulation-induced contractions will be delivered using an electrical stimulator connected to a pair of 5×5 cm self-adhesive surface electrodes. Stimulation will be applied in a superimposed manner during voluntary movement, at a frequency of 75 Hz and a phase duration of 400 µs. | Device | Control with sham stimulation, Electrical stimulation applied at the maximum tolerated intensity, Sensory-level electrical stimulation |
Primary outcome
Pain level
Time frame: Immediately after the performance of the functional task
Pain intensity during the single leg heel rise task will be assessed using the Visual Analog Scale, consisting of a numerical scale ranging from 0 to 10 points, in which 0 represents no pain and 10 corresponds to the worst pain ever experienced by the participant.
15 secondary outcomes
Total time
Time frame: Immediately after the performance of the functional task.
Maximal displacement
Time frame: Immediately after the performance of the functional task.
Total work
Time frame: Immediately after the performance of the functional task.
Total power
Time frame: Immediately after the performance of the functional task.
Number of repetitions
Time frame: Immediately after the performance of the functional task.
Peripheral oxygen extraction
Time frame: Immediately after the performance of the functional task.
Maximal Achilles tendon displacement
Time frame: Immediately after the performance of the functional task.
Lenght of achilles tendon
Time frame: Baseline (prior to Block A only)
Thickness of achilles tendon
Time frame: Baseline (prior to Block A only)
Cross-sectional area of achilles tendon
Time frame: Baseline (prior to Block A only)
Presence of neovascularization of the Achilles tendon
Time frame: Baseline (prior to Block A only)
Elastic modulus
Time frame: Baseline (prior to Block A only)
Shear wave velocity
Time frame: Baseline (prior to Block A only)
Depth
Time frame: Baseline (prior to Block A only)
Isometric strength
Time frame: Baseline (prior to Block A only)
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Mar 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Neuromuscular Electrical Stimulation (NMES) in people with Achilles Tendinopathy (AT) and Achilles Tendon Rupture, run by University of Brasilia at 1 site in Brazil.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 6 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Brazil. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact João LQ Durigan, PhD (+55 61 3107-8450, joaodurigan@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Pain level (time frame: Immediately after the performance of the functional task). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Mar 2026.