Lower-Extremity Kinetic Chain Exercise Program for Achilles Tendinopathy

Background Achilles tendinopathy is one of the most common overuse conditions affecting the lower limb. It is characterized by activity-related pain, localized tenderness, reduced tendon function, and decreased tolerance to loading. These symptoms can limit daily activities, reduce participation in sports or exercise, and affect overall quality of life.

Exercise-based rehabilitation is considered the primary conservative treatment for Achilles tendinopathy. Traditional rehabilitation programs mainly focus on strengthening the Achilles tendon and calf muscles. However, factors such as muscle weakness, impaired neuromuscular control, altered movement patterns, and reduced postural stability elsewhere in the lower extremity may also contribute to symptoms and functional limitations.

The lower-extremity kinetic chain refers to the coordinated interaction of the foot, ankle, knee, hip, pelvis, muscles, fascia, ligaments, and other connective tissues during movement. Changes in the function of one part of this system may influence movement mechanics and loading across the Achilles tendon. A rehabilitation program that addresses the entire kinetic chain may therefore provide a broader approach to managing individuals with chronic Achilles tendinopathy.

Objective

The objective of this randomized controlled trial is to evaluate the effects of a lower-extremity kinetic chain-based exercise program on postural stability, pain intensity, ankle range of motion, and functional outcomes in patients with chronic Achilles tendinopathy.

Study Design

This prospective randomized controlled trial will include 50 adults diagnosed with chronic Achilles tendinopathy. Eligible participants will be randomly assigned to one of two groups:

Experimental Group: Lower-extremity kinetic chain-based exercise program added to conventional rehabilitation program.

Control Group: Conventional rehabilitation program only.

Outcome assessments will be performed before the intervention and immediately after the intervention by an assessor who is blinded to group allocation.

Outcome Measures

The study will assess the following outcomes:

Postural Stability: Overall Stability Index (OSI) will be measured using the Biodex Balance System.

Foot and Ankle Function: Assessed using the Foot and Ankle Outcome Score (FAOS).

Pain Intensity Level: Evaluated using the Visual Analog Scale (VAS). Ankle Range of Motion: Measured using a universal goniometer. Significance

This study will examine a rehabilitation approach that combines exercises targeting the Achilles tendon with exercises designed to improve the coordinated function of the entire lower extremity. The findings will provide information about the effects of this intervention on balance, pain, ankle mobility, and functional performance in patients with chronic Achilles tendinopathy. The results may help inform future rehabilitation strategies and contribute to the evidence supporting exercise-based management of this condition.

Inclusion criteria

• Adults aged 18-45 years.

• Male and female participants.
• Clinical diagnosis of Achilles tendinopathy, confirmed by an orthopedic physician or physiotherapist and history of Achilles tendon surgery or lower-limb surgery within the previous 12 months.
• Symptoms (pain, stiffness, and impaired function) persisting for at least 3 months (chronic Achilles tendinopathy).
• Pain reproduced during tendon-loading activities (e.g., walking, running, hopping, or single-leg heel raises).
• Ability to walk independently without an assistive device.
• Body Mass Index (BMI) between 18.5 and <30 kg/m².
• Willingness to participate and provide written informed consent.

Exclusion criteria

• Patients with insertional Achilles tendinopathy or a partial/complete Achilles tendon rupture.

History of lower-limb fracture within the previous 12 months.

• Presence of systemic inflammatory, rheumatologic, or connective tissue disorders (e.g., rheumatoid arthritis, ankylosing spondylitis).
• Neurological disorders affecting balance, gait, or lower-limb function (e.g., stroke, Parkinson's disease, peripheral neuropathy, multiple sclerosis).
• Vestibular disorders or other conditions known to impair postural stability.