Lateral epicondylitis (LE) is a common musculoskeletal disorder caused by repetitive overuse of the forearm extensor muscles. It is characterized by pain over the lateral epicondyle of the humerus, which may radiate to the surrounding tissues at the origin of the wrist extensor tendons. LE is one of the most frequent causes of lateral elbow pain, with a reported prevalence of approximately 1-3% in the general population.

Among conservative interventions, exercise-based rehabilitation is considered a cornerstone of management. In particular, exercise programs incorporating eccentric contractions have demonstrated superior clinical outcomes compared with several other exercise approaches and are therefore widely recommended.

Blood flow restriction training (BFRT) has recently emerged as an alternative rehabilitation strategy that promotes neuromuscular adaptations while using low mechanical loads. BFRT involves the application of a pneumatic cuff, tourniquet, or elastic band around the proximal portion of an extremity to partially restrict arterial inflow while substantially reducing venous return, thereby creating localized metabolic and hemodynamic stress during exercise.

The primary aim of this randomized controlled trial was to investigate the effects of BFRT on pain, functional status, pain-free grip strength, health-related quality of life, and ultrasonographic characteristics of the common extensor tendon in patients with lateral epicondylitis.

Lateral epicondylitis (LE) is a common musculoskeletal disorder caused by repetitive overuse of the forearm extensor muscles. It is characterized by pain over the lateral epicondyle of the humerus, which may radiate to the surrounding tissues at the origin of the wrist extensor tendons. LE is one of the most frequent causes of lateral elbow pain, with a reported prevalence of approximately 1-3% in the general population. Although numerous conservative and invasive treatment modalities have been described, no universally accepted treatment algorithm currently exists. Among conservative interventions, exercise-based rehabilitation is considered a cornerstone of management because it improves tendon load tolerance, increases muscle strength, and facilitates functional recovery.

Although no consensus has been reached regarding the optimal exercise protocol, recent research has focused on interventions that enhance the adaptation of the common extensor tendon to mechanical loading. In particular, exercise programs incorporating eccentric contractions have demonstrated superior clinical outcomes compared with several other exercise approaches and are therefore widely recommended. Furthermore, regular exercise has been shown to improve tendon mechanical properties by increasing collagen synthesis as well as collagen fiber number and diameter.

To achieve meaningful improvements in muscle strength and hypertrophy, resistance exercise is generally recommended at loads of at least 70% of the one-repetition maximum (1RM). However, such loading is often poorly tolerated by individuals experiencing pain, muscle weakness, or muscle atrophy during the early stages of musculoskeletal rehabilitation. Consequently, high-intensity resistance exercise may exacerbate symptoms and reduce treatment adherence.

Blood flow restriction training (BFRT) has recently emerged as an alternative rehabilitation strategy that promotes neuromuscular adaptations while using low mechanical loads. BFRT involves the application of a pneumatic cuff, tourniquet, or elastic band around the proximal portion of an extremity to partially restrict arterial inflow while substantially reducing venous return, thereby creating localized metabolic and hemodynamic stress during exercise.

In BFRT, resistance exercises are typically performed at 20-30% of the one-repetition maximum (1RM). Despite the low training intensity, accumulating evidence indicates that BFRT can produce gains in muscle strength and hypertrophy comparable to those achieved with conventional high-intensity resistance training.

These characteristics make BFRT an attractive adjunct or alternative to traditional resistance exercise in musculoskeletal rehabilitation, particularly for minimizing excessive tissue loading during tendon healing, preventing muscle atrophy, and preserving functional capacity. Nevertheless, evidence regarding the effects of BFRT on clinical outcomes and tendon morphology in patients with lateral epicondylitis remains limited.

The primary aim of this randomized controlled trial was to investigate the effects of BFRT on pain, functional status, pain-free grip strength, health-related quality of life, and ultrasonographic characteristics of the common extensor tendon in patients with lateral epicondylitis. A secondary aim was to compare these outcomes with those achieved using a conventional exercise program and to determine whether BFRT induces measurable structural changes in tendon morphology as assessed by ultrasonography.

Inclusion Criteria:

• age between 18 and 75 years;
• clinical diagnosis of lateral epicondylitis based on medical history and physical examination;
• pain intensity of ≥4 on a 10-cm Visual Analog Scale (VAS) during daily activities;
• provision of written informed consent.

Exclusion Criteria:

• hypertension, diabetes mellitus, cardiovascular disease, peripheral vascular disease, previous deep vein thrombosis, or lymphedema;
• orthopedic, rheumatologic, or neurological disorders affecting the upper extremity;
• fibromyalgia;
• congenital or acquired elbow deformity;
• previous trauma, fracture, or surgery involving the affected upper extremity;
• cervical radiculopathy or peripheral neuropathy affecting the involved limb;
• receipt of any treatment for lateral epicondylitis within the preceding 3 months;
• skin lesions, infection, or open wounds at the cuff application site;
• bleeding disorders or current anticoagulant therapy;
• pregnancy;
• active malignancy or a history of malignancy;
• cognitive impairment or neurological or psychiatric disorders that could interfere with comprehension of study procedures or completion of outcome assessments.

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