Validity, Reliability, and Clinical Correlates of Immersive Virtual Reality Adaptation of the Five Times Sit-to-stand Test and Timed up and go Tests in Women With Fibromyalgia Syndrome

Performance outcomes will be assessed using the Five Times Sit-to-Stand Test (5xSTS) and the Timed Up and Go (TUG) test. These tests are widely used functional performance measures with established validity and reliability.

In this study, virtual reality (VR) adaptations of both tests will also be applied. Participants will enter the testing environment using a VR headset, and test protocols will be conducted in the same manner as the conventional applications. The VR-based assessments will follow standardized procedures equivalent to the traditional versions of the 5xSTS and TUG tests.

Hand grip strength will be measured in a seated position following standardized testing posture, with the shoulder adducted and in neutral rotation, the elbow flexed to 90 degrees, the forearm supported in mid-rotation, and the wrist in a neutral position. Measurements will be obtained from the dominant hand using a handheld dynamometer. Participants will be instructed to perform a maximal voluntary contraction. Three trials will be conducted with 15-second rest intervals, and the highest value will be recorded in kilograms (kg).

Knee extension muscle strength will be measured using a handheld dynamometer in a seated position with the hip and knee flexed to 90 degrees. The lower legs will hang freely, and the arms will be crossed over the chest. The dynamometer will be positioned perpendicular to the leg, 1-2 cm proximal to the malleoli, with stabilization applied at the thigh. Three measurements will be obtained, and the highest value will be recorded in kilograms (kg)

Physical activity level will be assessed using the 7-item short form of the International Physical Activity Questionnaire. The questionnaire evaluates time spent sitting, walking, moderate-intensity activities, and vigorous-intensity activities during the previous 7 days. Duration (minutes) and frequency (days) of each activity will be recorded. Total physical activity score will be calculated by multiplying activity duration by the corresponding metabolic equivalent (MET) value and summing all activity scores. Physical activity levels will be classified as physically inactive (<600 MET-min/week), minimally active (600-3000 MET-min/week), or active (>3000 MET-min/week).

Balance will be assessed using the single-leg balance test under eyes-open and eyes-closed conditions. Participants will stand on the dominant leg with the arms crossed over the chest while the contralateral leg is lifted from the ground with the knee flexed to approximately 45 degrees. Timing will begin once the test position is achieved. The test will be terminated if the arms or the non-stance leg are used for support or when the maximum duration of 30 seconds is reached. Time will be recorded in seconds. Each condition will be repeated three times, and the best performance will be recorded. The same procedure will be applied to the nondominant leg