his randomized controlled crossover study aims to investigate the acute effects of lower limb blood flow restriction (BFR) on ankle joint proprioception, postural control, and muscle activation in healthy adults. Each participant will complete test sessions under BFR (60% individualized arterial occlusion pressure) and control (20 mmHg sham) conditions. Outcome measures include joint position sense, kinesthesia, static and dynamic balance performance, and electromyographic (EMG) activity and reaction times of selected lower limb tibialis anterior and peroneus longus muscles.

Lateral ankle sprains are among the most common musculoskeletal injuries and may lead to chronic ankle instability (CAI), partly due to impaired proprioception and neuromuscular control. Blood flow restriction (BFR) training is widely used to augment muscular adaptations with low external loads; however, its acute effects on joint proprioception and sensorimotor control, particularly at the ankle joint, remain unclear and may be detrimental under certain conditions. This randomized controlled crossover trial will examine the effects of a single-session lower limb BFR application on ankle joint position sense, kinesthesia, static and dynamic balance, and EMG-based reaction time and activity of lower limb muscles in healthy adults. Participants aged 18-40 years without recent ankle sprain, neuromuscular, cardiovascular, or thromboembolic disease will undergo standardized proprioception tests using an isokinetic dynamometer, static balance tests on a force platform, Y-balance test, and inversion simulation platform assessments under BFR (60% arterial occlusion pressure) and low-pressure control (20 mmHg) conditions. Individual arterial occlusion pressure (AOP) will be determined using Doppler ultrasound, and BFR will be applied with a pneumatic cuff at the most proximal thigh. All measurements will be performed on the dominant lower limb with sessions scheduled at the same time of day to minimize circadian variability. The primary hypothesis is that acute lower limb BFR will worsen ankle joint proprioception and sensorimotor control compared with the control condition, potentially indicating a transient increase in injury risk during BFR-assisted activities.

Inclusion Criteria:

• Aged between 18 and 40 years
• No known neuromuscular or cardiovascular disease

Exclusion Criteria:

• History or presence of cardiac, coronary artery, or peripheral arterial disease
• Presence or history of varicose veins, hypertension, diabetes mellitus, or pulmonary disease
• History of pulmonary embolism or deep vein thrombosis
• Use of medications affecting the central nervous or cardiovascular systems
• Use of oral contraceptives or anticoagulants
• Pregnancy
• Open wounds or significant scar tissue at the cuff application site
• History of lower extremity musculoskeletal injury or surgery
• Any neurological, vascular, or systemic condition that may interfere with test performance