Eccentric vs Low-Load Blood Flow Restriction Training in Knee Osteoarthritis in Knee Osteoarthritis

Osteoarthritis (OA) is a chronic disease affecting the joint and its tissues, primarily leading to progressive damage to articular cartilage and, subsequently, to the subchondral bone and surrounding synovial structures. This chronic degenerative disease affects approximately one-third of adults, and its prevalence increasing with advancing age. The knee is one of the most common joints affected by the OA. Systematic reviews indicate a global prevalence of knee osteoarthritis (KOA) is 22.9% among individuals aged 40 and older, affecting an estimated 654.1 million people worldwide, with variations across countries and increasing with age.

Knee osteoarthritis (KOA) is a multi etiological, chronic disabling disease that affects the entire knee joint, which is the most common site of involvement in OA. KOA patients mostly suffer from progressive stiffness and knee pain. Gradually, they have some difficulties in performing daily activities, such as walking, squatting, and climbing and doing housework, as the disease progresses. Ultimately, pain and disability associated with the disease lead to a loss of functional independence and a profound reduction in quality-of- life. Impairments that are caused by KOA include knee pain, limited ROM of the knee, muscle weakness and knee instability.

The gastrocnemius muscle plays a crucial role in knee joint stability and ankle-knee biomechanics through its biarticular function, contributing to both knee flexion and ankle plantarflexion. During the stance phase of gait, the gastrocnemius co-activates with the tibialis anterior and quadriceps muscles, providing dynamic stability, reducing medial knee laxity, and assisting in forward propulsion.

The impaired neuromuscular recruitment of the gastrocnemius may result in reduced push-off strength, prolonged ground contact time, and diminished functional performance, ultimately contributing to functional limitations in patients with knee osteoarthritis. However, surface electromyography (sEMG) enables the assessment of gastrocnemius motor unit recruitment and fatigue characteristics, providing objective insight into neuromuscular adaptations before and after targeted interventions.

OA of the knee is characterized by changes in gait kinematics. In patients with knee OA, deficits in gastrocnemius strength and endurance can exacerbate difficulties in activities such as stair climbing, walking, and balance maintenance. Eccentric and low-load blood flow restriction (LL-BFR) training protocols have been proposed to optimize gastrocnemius activation, enhance muscle strength, and improve functional performance, offering clinically relevant rehabilitation strategies for enhancing lower limb function and reducing disability in knee osteoarthritis.

This study is to find the effects of eccentric and low-load blood flow restriction training on neuromuscular adaptations, muscle strength, functional performance, and disability in individuals affected by the knee OA.

Inclusion criteria

• Age group 40-70
• Both genders male and female
• Clinical diagnosis of knee OA (Kellgren-Lawrence grade 1-3) of the most symptomatic knee.
• Pain stable enough to permit exercise on Numeric Pain Rating Scale 3/10.
• Participants must demonstrate a gastrocnemius muscle strength of grade ≥3 on the Manual Muscle Testing (MMT) scale (0-5), assessed using the standard standing heel-rise position.
• Participants must be able to ambulate independently and participate in supervised exercise.

Exclusion criteria

• • Presence of a prosthetic knee in the affected limb.

• Inflammatory arthritis (e.g., rheumatoid arthritis) or active flare-up of OA.
• Cardiovascular disease contraindicating exercise (e.g., unstable angina, recent MI, uncontrolled hypertension ≥160/100 mmHg).
• Pulmonary disease that limits safe participation (e.g., severe COPD, recent exacerbation).
• History of deep vein thrombosis (DVT), peripheral vascular disease, or bleeding/clotting disorders.
• Current anticoagulant therapy that increases bleeding risk (unless cleared by physician).
• Any pathology causing significant muscle weakness (e.g., neuromuscular disorders, severe neuropathy).