Achilles TendinopathyNCT06774547
Early Implementation of Plyometric Exercises in the Rehabilitation of Individuals Suffering From Lower-Extremity Tendinopathies
A study testing Heavy-slow resistance training and Plyometric exercise in people with Achilles Tendinopathy and Patellar Tendinopathy, run by Aalborg University at 1 site in Denmark.
Trial summary
This clinical trial aims to compare the effectiveness of an early plyometric exercise approach with traditional heavy, slow resistance training in treating tendinopathies of the Achilles tendon, patellar tendon, and plantar fascia. Read more about this study
- Who is it for?
- Ages 18 to 50 years
- Conditions the study is for
- Achilles Tendinopathy, Patellar Tendinopathy, Plantar Fasciopathy
- What is being tested?
- Heavy-slow resistance training and Plyometric exercise
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 120 participants
- Where
- 1 siteDenmark
- Study dates
- 18 Sep 2025to Jan 2028
- 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 50 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- participants are required to have performed either recreational running or participated in sports that include running or jumping activities (e.g., football, basketball, handball, volleyball) at least once per week for at least three months immediately prior to pain onset
- have had symptoms for at least three months
- have pain/soreness with palpation of the tendon/fascia
- mean pain during the past week of at least 2 on a 0 to 10 Numerical Rating Scale
- pain during a pain provocation test (patellar tendinopathy: five single-legged decline squats, Achilles tendinopathy and plantar fasciopathy: ten single-legged heel raises)
Who cannot join
- previous lower-extremity surgery
- other lower-extremity musculoskeletal conditions that have required treatment by a healthcare professional during the past three months
- pregnancy
- diabetes
- history of inflammatory systemic diseases (e.g., rheumatoid arthritis or spondylarthritis)
- having received an injection with corticosteroid within the past six months.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Denmark1 site, 1 recruiting
- Recruiting
University College of Northern Denmark
Aalborg, 9220
Henrik Riel, 0045 72691014, heri@ucn.dk
About this study
Official title: The Efficacy of Early Implementation of Plyometric Exercises in the Rehabilitation of Individuals Suffering From Lower-Extremity Tendinopathies: A Randomised Clinical Trial
This clinical trial aims to compare the effectiveness of an early plyometric exercise approach with traditional heavy, slow resistance training in treating tendinopathies of the Achilles tendon, patellar tendon, and plantar fascia. These conditions, commonly seen in general and rheumatology practices, cause pain, reduced function, and stiffness, often leading to prolonged recovery and incomplete return to full physical activity. The study hypothesizes that introducing plyometric exercises early in rehabilitation will improve jump function after 12 weeks and reduce re-injury rates within 52 weeks compared to traditional methods.
The study is a randomized clinical trial including 120 participants aged 18-50 with tendinopathy in one of the targeted areas. Participants must regularly engage in running or jumping sports, have symptoms for at least three months, and meet other inclusion criteria. Exclusion criteria include recent surgery or specific medical conditions. Both groups will perform exercises three times weekly for 12 weeks, tailored to their tendinopathy. The intervention group will add progressive plyometric exercises to the standard strength training performed by the control group. Plyometric training will consist of three levels, with patients self-assessing readiness to progress.
The primary outcome is the change in the plyometric quotient, a measure of functional ability, based on a jump test using a force platform at 0 and 12 weeks. Secondary outcomes include dynamic strength, jump height, patient-reported symptoms (via questionnaires), return to sport, training compliance, adverse events, pain thresholds, re-injury rates, and psychological readiness for sports. Assessments will occur at baseline, 12 weeks, and 52 weeks.
Read the detailed description
This trial is a randomised clinical trial with a 12-week intervention. The trial will be conducted at the Department of Physiotherapy, University College of Northern Denmark, Aalborg, Denmark. Participants will be stratified by their condition and block randomised (block sizes of 2 to 6) 1:1 to either 1) heavy-slow resistance training or 2) heavy-slow resistance training plus a plyometric exercise regimen. A researcher not involved in the trial will generate the allocation sequence using a random number generator and is the only person who will know the block sizes.
- Being tested
- Heavy-slow resistance training, Plyometric exercise
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Heavy-slow resistance trainingOther
Heavy-slow resistance training consists of a progressive protocol of dynamic exercises where the relative load increases over time from a weight that can only be lifted 15 times (i.e., 15 repetition maximum) during the first week to a relative load of 6 repetition maximum from Week 9 to 12. The exercises are performed unsupervised three days per week separated by a minimum of 48 hours. There are two exercises that are performed for four sets separated by a 2-minute rest. Participants with Achilles tendinopathy or plantar fasciopathy perform seated and standing weighted heel raises and participants with patellar tendinopathy perform a free-standing squat and a seated leg press. Tolerable pain during the exercises is allowed.
Plyometric exerciseOther
The progressive plyometric programme consists of three different levels and is performed unsupervised three times per week separated by a minimum of 48 hours. Each level consists of several exercise sets that are separated by 2-minute rest intervals. Participants' self-evaluated readiness to progress to a higher level will guide the progression. Level 1 includes free-standing double-legged plyometric exercises where they push off the ground and lift their heels while maintaining contact with it. If the participant feels they can do more, they will progress to Level 2, where participants increase the relative load during the dynamic exercises and start performing plyometric double-legged jumps. At the highest level, Level 3, the relative load during the exercises is further increased, and the plyometric exercises are to be performed as single-legged hops. Tolerable pain during the exercises is allowed.
| Study group | Role | What they receive |
|---|---|---|
| Plyometrics | Experimental | Performing both heavy-slow resistance training and the plyometric protocol Receives: Other: Heavy-slow resistance training; Other: Plyometric exercise |
| Control | Active comparator | Perform heavy-slow resistance training Receives: Other: Heavy-slow resistance training |
What is being measured
The primary outcome is the main question the study is designed to answer.
Plyometric quotient
The plyometric quotient is calculated by dividing the flight time by the contact time during single-leg hops and has good to excellent reliability. The test is performed on a force plate where the participant is instructed to perform 25 hops at a frequency of around two hops per second standing on their affected limb (or most symptomatic if they have bilateral symptoms). The first three and last two hops are excluded, which means that 20 hops are used to assess the flight time and contact time.
Measured: From baseline to the 12-week follow-up
Secondary outcomes (15)
Plyometric quotient
The plyometric quotient is calculated by dividing the flight time by the contact time during single-leg hops and has good to excellent reliability. The test is performed on a force plate where the participant is instructed to perform 25 hops at a frequency of around two hops per second standing on their affected limb (or most symptomatic if they have bilateral symptoms). The first three and last two hops are excluded, which means that 20 hops are used to assess the flight time and contact time.
Measured: From baseline to the 52-week follow-up
Dynamic strength
Dynamic strength measured in knee extension and flexion and ankle plantar flexion by isokinetic dynamometry. The test is performed five times in each movement direction.
Measured: Baseline to the 12-week and 52-week follow-ups
Drop countermovement jump height
Measured in centimetres and derived from the hop test (see description of the primary outcome) on the force plate.
Measured: From baseline to the 12-week and 52-week follow-ups
Drop countermovement contact time
Measured in seconds and derived from the hop test (see description of the primary outcome) on the force plate.
Measured: From baseline to the 12-week and 52-week follow-ups
Victorian Institute of Sports Assessment - Achilles (VISA-A)
Questionnaire only for participants with Achilles tendinopathy. Total score ranges from 0 to 100, where 100 indicates no pain or dysfunction and 0 represents severe limitations
Measured: Baseline to the 12-week and 52-week follow-ups
TENDINS-A
Questionnaire only for participants with Achilles tendinopathy. The 13-item is scored between 0 and 100, with '0' representing a perfect score (no disability) and '100' representing complete disability.
Measured: From baseline to the 12-week and 52-week follow-ups
Foot Health Status Questionnaire
Questionnaire only for participants with plantar fasciopathy. Includes four core domains: foot pain, foot function, footwear, and general foot health.
Each domain is scored separately, ranging from 0 (poor foot health) to 100 (optimal foot health).
Measured: Baseline to the 12-week and 52-week follow-ups
VISA-P
Questionnaire only for participants with patellar tendinopathy. Total score ranges from 0 to 100, with 100 indicating optimal function and 0 reflecting severe dysfunction.
Measured: Baseline to the 12-week and 52-week follow-ups
Global Rating of Change
A 7-point numerical rating scale that evaluates participants' improvement compared to before treatment. Participants are dichotomised as improved if they rate themselves as 'much improved' or 'improved' (categories 6 and 7) and categorised as not improved if they rate themselves from 'slightly improved' to 'much worse' (categories 1 to 5)
Measured: During the 12-week and 52-week follow-ups
Exercise compliance and fidelity
Based on training diaries. Exercise compliance relates to whether the training sessions have been performed, and fidelity relates to whether the exercises have been performed as prescribed regarding the number of repetitions, sets, and intensity.
Measured: During the 12-week intervention.
Rate of return to sport
Measured by a self-developed questionnaire that includes questions regarding their physical performance and participation in sports
Measured: During the 12-week and 52-week follow-ups
Adverse events
Adverse events will be collected throughout the trial and graded 1 to 5 according to the Common Terminology Criteria for Adverse Events v4.03. Participants are asked to contact the responsible clinician as soon as they experience any adverse event.
Measured: Throughout the time participants are enrolled (52 weeks)
Pressure pain thresholds
Pressure pain thresholds measured by a pressure algometer on the tendon (Achilles or patella) or plantar fascia depending on the tendinopathy and the contralateral elbow. The test is performed with a handheld pressure algometer. The probe is placed perpendicular to the skin, and pressure is applied at a rate of 30 kPa/s. The participants are instructed to push the button of a hand-held switch when they first feel the sensation of pressure change to a sensation of pain, and the test is terminated
Measured: From baseline to the 12-week and 52-week follow-ups
Re-injury
Rate of re-injury measured using the modified Oslo Sports Trauma Research Centre (OSTRC) Overuse Injury Questionnaire.
Measured: During the 12-week and 52-week follow-ups
Psychological readiness to return to sport
Psychological readiness to return to sport measured by the Injury-Psychological Readiness to Return to Sport (I-PRRS) Scale. Participants respond to 10 items, depending on the version, related to confidence, emotional state, and readiness.
Each item is scored on a scale of 0 to 100. 0 = Not confident/ready at all. 100 = Fully confident/ready
Measured: Baseline to the 12-week and 52-week follow-ups
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Jan 2025
- Study start18 Sep 2025
- Primary completionOct 2027 (estimated)
- Study completionJan 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Achilles TendinopathyStudies 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
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 120 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Aalborg University
- Sponsor type
- University, hospital or other
- Collaborators
- Department of Physiotherapy, University College of Northern Denmark
- Responsible party
- Principal investigator, Henrik Riel, Aalborg University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06774547
- Sponsor's protocol ID
- N-20240042
- Status last verified
- Mar 2026
- First submitted
- 3 Jan 2025
- Last updated
- 4 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: Data will be made available upon reasonable request.
Study at a glance
From the registry record, last updated by the sponsor on 4 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Efficacy of Early Implementation of Plyometric Exercises in the Rehabilitation of Individuals Suffering From Lower-Extremity Tendinopathies: A Randomised Clinical Trial
- ClinicalTrials.gov ID
- NCT06774547
- Acronym / sponsor ID
- N-20240042
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 120 participants (estimated)
- Lead sponsor
- Aalborg UniversityUniversity, hospital or other
- Collaborators
- Department of Physiotherapy, University College of Northern Denmark
- Study start
- 18 Sep 2025 (actual)
- Primary completion
- Oct 2027 (estimated)
- Study completion
- Jan 2028 (estimated)
- First posted
- 14 Jan 2025 (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.
This clinical trial aims to compare the effectiveness of an early plyometric exercise approach with traditional heavy, slow resistance training in treating tendinopathies of the Achilles tendon, patellar tendon, and plantar fascia. These conditions, commonly seen in general and rheumatology practices, cause pain, reduced function, and stiffness, often leading to prolonged recovery and incomplete return to full physical activity. The study hypothesizes that introducing plyometric exercises early in rehabilitation will improve jump function after 12 weeks and reduce re-injury rates within 52 weeks compared to traditional methods.
The study is a randomized clinical trial including 120 participants aged 18-50 with tendinopathy in one of the targeted areas. Participants must regularly engage in running or jumping sports, have symptoms for at least three months, and meet other inclusion criteria. Exclusion criteria include recent surgery or specific medical conditions. Both groups will perform exercises three times weekly for 12 weeks, tailored to their tendinopathy. The intervention group will add progressive plyometric exercises to the standard strength training performed by the control group. Plyometric training will consist of three levels, with patients self-assessing readiness to progress.
The primary outcome is the change in the plyometric quotient, a measure of functional ability, based on a jump test using a force platform at 0 and 12 weeks. Secondary outcomes include dynamic strength, jump height, patient-reported symptoms (via questionnaires), return to sport, training compliance, adverse events, pain thresholds, re-injury rates, and psychological readiness for sports. Assessments will occur at baseline, 12 weeks, and 52 weeks.
Detailed description
This trial is a randomised clinical trial with a 12-week intervention. The trial will be conducted at the Department of Physiotherapy, University College of Northern Denmark, Aalborg, Denmark. Participants will be stratified by their condition and block randomised (block sizes of 2 to 6) 1:1 to either 1) heavy-slow resistance training or 2) heavy-slow resistance training plus a plyometric exercise regimen. A researcher not involved in the trial will generate the allocation sequence using a random number generator and is the only person who will know the block sizes.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Plyometrics | Experimental | Other: Heavy-slow resistance training, Other: Plyometric exercisePerforming both heavy-slow resistance training and the plyometric protocol |
| Control | Active comparator | Other: Heavy-slow resistance trainingPerform heavy-slow resistance training |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- participants are required to have performed either recreational running or participated in sports that include running or jumping activities (e.g., football, basketball, handball, volleyball) at least once per week for at least three months immediately prior to pain onset
- have had symptoms for at least three months
- have pain/soreness with palpation of the tendon/fascia
- mean pain during the past week of at least 2 on a 0 to 10 Numerical Rating Scale
- pain during a pain provocation test (patellar tendinopathy: five single-legged decline squats, Achilles tendinopathy and plantar fasciopathy: ten single-legged heel raises)
Key exclusion criteria (6 listed)
- previous lower-extremity surgery
- other lower-extremity musculoskeletal conditions that have required treatment by a healthcare professional during the past three months
- pregnancy
- diabetes
- history of inflammatory systemic diseases (e.g., rheumatoid arthritis or spondylarthritis)
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 |
|---|---|---|
| Heavy-slow resistance trainingHeavy-slow resistance training consists of a progressive protocol of dynamic exercises where the relative load increases over time from a weight that can only be lifted 15 times (i.e., 15 repetition maximum) during the first week to a relative load of 6 repetition maximum from Week 9 to 12. The exercises are performed unsupervised three days per week separated by a minimum of 48 hours. There are two exercises that are performed for four sets separated by a 2-minute rest. Participants with Achilles tendinopathy or plantar fasciopathy perform seated and standing weighted heel raises and participants with patellar tendinopathy perform a free-standing squat and a seated leg press. Tolerable pain during the exercises is allowed. | Other | Control, Plyometrics |
| Plyometric exerciseThe progressive plyometric programme consists of three different levels and is performed unsupervised three times per week separated by a minimum of 48 hours. Each level consists of several exercise sets that are separated by 2-minute rest intervals. Participants' self-evaluated readiness to progress to a higher level will guide the progression. Level 1 includes free-standing double-legged plyometric exercises where they push off the ground and lift their heels while maintaining contact with it. If the participant feels they can do more, they will progress to Level 2, where participants increase the relative load during the dynamic exercises and start performing plyometric double-legged jumps. At the highest level, Level 3, the relative load during the exercises is further increased, and the plyometric exercises are to be performed as single-legged hops. Tolerable pain during the exercises is allowed. | Other | Plyometrics |
Primary outcome
Plyometric quotient
Time frame: From baseline to the 12-week follow-up
The plyometric quotient is calculated by dividing the flight time by the contact time during single-leg hops and has good to excellent reliability. The test is performed on a force plate where the participant is instructed to perform 25 hops at a frequency of around two hops per second standing on their affected limb (or most symptomatic if they have bilateral symptoms). The first three and last two hops are excluded, which means that 20 hops are used to assess the flight time and contact time.
15 secondary outcomes
Plyometric quotient
Time frame: From baseline to the 52-week follow-up
Dynamic strength
Time frame: Baseline to the 12-week and 52-week follow-ups
Drop countermovement jump height
Time frame: From baseline to the 12-week and 52-week follow-ups
Drop countermovement contact time
Time frame: From baseline to the 12-week and 52-week follow-ups
Victorian Institute of Sports Assessment - Achilles (VISA-A)
Time frame: Baseline to the 12-week and 52-week follow-ups
TENDINS-A
Time frame: From baseline to the 12-week and 52-week follow-ups
Foot Health Status Questionnaire
Time frame: Baseline to the 12-week and 52-week follow-ups
VISA-P
Time frame: Baseline to the 12-week and 52-week follow-ups
Global Rating of Change
Time frame: During the 12-week and 52-week follow-ups
Exercise compliance and fidelity
Time frame: During the 12-week intervention.
Rate of return to sport
Time frame: During the 12-week and 52-week follow-ups
Adverse events
Time frame: Throughout the time participants are enrolled (52 weeks)
Pressure pain thresholds
Time frame: From baseline to the 12-week and 52-week follow-ups
Re-injury
Time frame: During the 12-week and 52-week follow-ups
Psychological readiness to return to sport
Time frame: Baseline to the 12-week and 52-week follow-ups
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 4 Mar 2026.
- Individual participant dataSharing planned: Undecided. Data will be made available upon reasonable request.
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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 Heavy-slow resistance training and Plyometric exercise in people with Achilles Tendinopathy and Patellar Tendinopathy, run by Aalborg University at 1 site in Denmark.
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 5 inclusion and 6 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 4 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 Denmark. 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. 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 Henrik Riel, PhD (0045 72691014, heri@ucn.dk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Plyometric quotient (time frame: From baseline to the 12-week follow-up). 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 4 Mar 2026.