Effects of Low-load Resistance Training With Blood Flow Restriction in Patients With Achilles Tendinopathy

Midportion Achilles tendinopathy (MAT) is a common overuse injury of the lower extremity characterized by the presence of pain, restricted function and interruption of sport activities. Conservative management of MAT has been suggested as the first line of treatment. Actually, there are several exercise programs with beneficial effects on pain and function among which high load training stands out. However, this training modality is inherently difficult to implement in certain populations and pathological conditions due to their inability to tolerate this mechanical stress. In this sense, low load training with blood flow restriction (BFR-LLT) emerges as an effective option in producing hypertrophic adaptations with low intensities (30% 1RM). However, this training modality has not yet been studied in tendon pathology. The aim of this study is to evaluate the potential clinical effects of BFR-LLT in comparison with HLT in patients with chronic MAT.

The aim of this study will be to evaluate the potential clinical effects of low load training with blood flow restriction (BFR-LLT) in comparison with high load training (HLT) in patients with chronic midportion Achilles tendinopathy (MAT). The secondary objectives will be to determine if there are differences in the neovascularity and thickness, pain and function of the AT between both groups in each instance of evaluation. This study will be a simple-blinded randomized clinical trial comprising a total sample size of 52 participants with MAT of both genders and aged between 18 and 50 years. Subjects will undergo a screening process by a sports medicine doctor by different diagnostic tests to identify those presenting a diagnosis of painful MAT and then, they will be randomized into either a group performing HLT (G1), or a group performing BFR-LLT (G2). These volunteers will be recruited in the Parque Hospital (Rosario, Argentine). The study will assess the subjects tendon pain, thickness, cross sectional area and neovascularity, lower limb function, calf raise endurance and jump height. The training protocol will be performed in the University of Gran Rosario (Rosario, Argentine) and will consist of three weekly training sessions during a 12-week rehabilitation period. Primary and secondary outcomes will be measured at baseline, 6 and 12 weeks. All the evaluations will be performed by a blinded physiotherapist.

Eligibility Criteria:
Inclusion Criteria:

* Clinical diagnosis of unilateral MAT.
* Achilles pain \> 3 months.
* Age ranging between 18 to 50 years, both genders.
* Read and speak Spanish well enough to provide informed consent and follow study instructions.
* Can attend in-clinic treatments 2-3 x weekly for the next 12 weeks.

Exclusion Criteria:

* Any ankle or foot surgery.
* History of Achilles rupture.
* Heel pain in the last 3 months.
* Systemic disorders/diseases.
* History of deep venous thrombosis, hypertension or blood clotting disorder.
* Body mass index \> 30kg/m2.
* Self-report of pregnancy.
* Drug use (local steroid injection or systemic fluoroquinolones).
* Pain \< 2/10 of average pain on NPRS.
* VISA A score \> 90%.
* Unable to perform any of the exercises of the study.