Blood Flow Restriction Training for Treatment of Chronic Patellar Tendinopathy

The Effect of Low-Load Resistance Training With Blood Flow Restriction for Treatment of Chronic Patellar Tendinopathy - A Randomized Clinical Trial

The purpose of this study is to investigate the clinical and functional outcome of a 12-week rehabilitation regime consisting of Low-Load Blood Flow Restriction compared to Heavy-Slow Resistance training in male patients with chronic unilateral patellar tendinopathy.

Chronic tendinopathy represents a considerable problem in both elite and recreational athletes, and symptoms may affect athletic performance and reduce or even result in retirement from sports participation. The current best treatment is considered to be heavy-slow resistance training (HSRT); however, not all patients are able to cope with heavy exercise loads. Therefore, low-load strength training performed under partial blood flow restriction may be a clinically relevant rehabilitation tool. This project aims to investigate a new innovative intervention to treat chronic unilateral patellar tendinopathy in male individuals using strength training with low-load muscle contractions performed under partial blood flow restriction (LL-BFR), and to compare the resulting treatment outcome to that of the current best practice (HSRT). Specifically, the effect of LL-BFR will be investigated using a randomized controlled trial design with two groups; 1) a low-load blood flow restriction training program, and 2) a heavy-load slow strength training program. A total sample size of 36 participants are needed when assuming a 10 % dropout. The training protocol consist of three weekly training sessions during a 12-week rehabilitation period. The primary outcome is measured using the Single-Leg Decline Squat at 12-week. If LL-BFR proves to be an effective treatment strategy for tendinopathy, it can easily be implemented in daily clinical practice.

Resistance training for knee extensors. The exercise will be performed at 80% of 1 RM and slowly (6 s/repetition).

Resistance training for knee extensors. The exercise will be performed at 30% of 1 RM and with a relative Artery Occlusion Pressure of 80%

Change from baseline - 12 weeks using the clinical functional test Single-Leg Decline Squat measured on the Numerical Rating Scale (NRS; 0= no pain, 10 = worst imaginable pain)

Single-Leg Decline Squat is a reliable patellar tendon pain provocation test used to assess pain during function.

A reliable patellar tendon pain provocation test, will be used to assess pain during function using the Numerical Rating Scale (NRS; 0= no pain, 10 = worst imaginable pain)

Participants will self-report how many hours a week they are performing sporting activities: We will monitor to see if they decrease, maintain or increase hours per week of sporting activity

Using Ultrasonography, we will measure Doppler activity within the affected tendon and use ImageJ for the analysis

Maximal muscle strength of the knee extensors is obtained during a maximal isometric voluntary contractions

Measured by a handheld pressure algometry at most painful site, Apex Patellar, Tibialis Anterior and Extensor Carpi Radialis.

The VISA-P is a questionnaire that assesses symptoms, simple test of function, and the ability to play sports. Max score for asymptomatic is 100 and worst score is 0

Inclusion Criteria: Unilateral patellar tendinopathy Chronic (symptoms >3 months) Pain of ≥ 4 during preferred sporting activity on the numerical pain rating scale (NRS; with 0 being no pain and 10 being the worst imaginable pain) Ultrasonographical tendon swelling Ultrasonographical hypo-echoic area with doppler Exclusion Criteria: Bilateral tendinopathy Cardiovascular diseases Diabetes Smoking Previous surgery or trauma to the knee joint with an effect on the presenting clinical condition Participants must not have been enrolled in a resistance based-rehabilitation program for the affected patellar tendon within the previous three months Previous corticosteroid injection for patellar tendinopathy

Department of Physical and Occupational Therapy / Institute of Sports Medicine Copenhagen, Bispebjerg Hospital