Effects of Blood Flow Restriction Training on Muscle Strength and Physical Function for Stroke-Related Sarcopenia

Isometric peak torque of the target muscle groups will be measured during both extension and flexion using an isokinetic dynamometer. The unit of measurement is Newton-meters (Nm). Higher values indicate greater muscle strength.

Motor function will be assessed using the Fugl-Meyer Assessment, a validated and widely used scale to evaluate motor recovery, particularly in individuals with neurological impairments such as stroke. The total score ranges from 0 to 226, with higher scores indicating better motor function. The assessment includes subscales for upper extremity, lower extremity, coordination, and reflex activity.

Aerobic capacity and walking endurance will be measured using the Six-Minute Walk Test. Participants will be instructed to walk as far as possible in six minutes on a flat, straight surface. The total distance walked will be recorded in meters. This test reflects submaximal functional capacity relevant to daily physical activity.

Functional mobility will be assessed using the Timed Up and Go Test. Participants will be asked to stand up from a chair, walk 3 meters, turn around, return to the chair, and sit down. The total time taken to complete the task will be recorded in seconds. Shorter times reflect better mobility.

Gait speed will be assessed using the 10-Meter Walk Test at maximum safe walking speed. Participants will be instructed to walk a total of 10 meters as fast as safely possible. The time taken to walk the middle 6 meters (excluding acceleration and deceleration zones) will be recorded, and gait speed will be calculated in meters per second (m/s). Higher values indicate better fast walking ability.

The Five Times Sit-to-Stand Test measures the time in seconds (s) required for a participant to rise from a standard chair to a full standing position and return to sitting five times consecutively as quickly as possible, with arms crossed over the chest. A stopwatch will be used. Lower times indicate better lower limb function and power.

Handgrip strength will be measured in kilograms (kg) using a digital hand dynamometer.

Nutritional status will be evaluated using the Mini Nutritional Assessment - Short Form (MNA-SF), a validated screening tool for identifying malnutrition or risk of malnutrition in older adults. The total score ranges from 0 to 14. Scores ≥12 indicate normal nutritional status, 8-11 at risk, and ≤7 malnourished.

Quality of life related to sarcopenia will be assessed using the Sarcopenia and Quality of Life Questionnaire (SarQoL), a disease-specific instrument for older adults with reduced muscle mass or function. It covers domains such as physical health, mental health, locomotion, and daily activities. Higher scores indicate better quality of life.

ASM will be assessed using bioelectrical impedance analysis (BIA) and reported in kilograms per square meter (kg/m²). This value is calculated as total limb lean mass divided by height squared, following the AWGS 2019 criteria.

Muscle thickness will be measured using B-mode ultrasonography with a high-frequency linear probe. Values will be reported in millimeters (mm). The average of three measurements will be used for each muscle. Muscle Thickness of Rectus Femoris and Medial Gastrocnemius.

Pennation angle will be obtained from ultrasound images using ImageJ software. The angle between the muscle fascicles and deep aponeurosis will be measured in degrees (°).

CSA will be measured from transverse ultrasound images and reported in square centimeters (cm²). Measurements will be taken at standardized anatomical landmarks.

Echo intensity will be calculated using grayscale analysis from ultrasound images and reported in arbitrary units (a.u.), based on pixel brightness (0 = black, 255 = white).