Early Implementation of Plyometric Exercises in the Rehabilitation of Individuals Suffering from Lower-Extremity Tendinopathies

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.

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.

Eligibility Criteria:
Inclusion Criteria:

1. participants are required to perform either recreational running or participate in sports that include running or jumping activities (e.g., football, basketball, handball, volleyball) at least once per week for at least three months before inclusion
2. have had symptoms for at least three months
3. have pain/soreness with palpation of the tendon/fascia
4. mean pain during the past week of at least 2 on a 0 to 10 Numerical Rating Scale
5. pain during a pain provocation test (patellar tendinopathy: five single-legged decline squats, Achilles tendinopathy and plantar fasciopathy: ten single-legged heel raises)

Exclusion Criteria:

1. previous lower-extremity surgery
2. other lower-extremity musculoskeletal conditions that have required treatment by a healthcare professional during the past three months
3. pregnancy
4. diabetes
5. history of inflammatory systemic diseases (e.g., rheumatoid arthritis or spondylarthritis)
6. having received an injection with corticosteroid within the past six months.