This study aims to evaluate the concurrent validity of a wearable motion sensor (BTS G-sensor) in measuring countermovement jump (CMJ) height. Healthy female volunteers between 18 and 35 years of age will perform CMJ tests. Jump height will be measured simultaneously using the BTS G-sensor and the My Jump smartphone application, which has previously demonstrated validity and reliability. The study will assess the level of agreement between the two measurement methods.

Vertical jump height is widely used as an indicator of lower limb strength and functional performance. Force platforms are the gold standard for jump height measurement but are expensive and not always practical. Wearable motion sensors and smartphone applications have been developed as low-cost and portable alternatives.

This observational study is designed to examine the concurrent validity of the BTS G-sensor, a wearable inertial measurement unit, for measuring countermovement jump (CMJ) height. Measurements obtained from the BTS G-sensor will be compared with those from the My Jump smartphone application, a validated reference tool.

Healthy female volunteers aged 18-35 years will perform countermovement jumps after a standardized warm-up. Each participant's jump height will be simultaneously recorded by both methods. Data will be analyzed using correlation and agreement analyses to determine the level of consistency between the two methods.

This is an observational validation study. Both the BTS G-sensor and the My Jump application were used simultaneously for measurement purposes only. No interventional procedure or assignment was applied to participants.

Clarification on Study Type:

This is an observational validation study. Both the BTS G-sensor and the My Jump smartphone application were used simultaneously for measurement purposes only. No participant assignment or interventional procedure was applied.

• Inclusion Criteria:Female volunteers aged 18-35 years
• No history of orthopedic injury in the past 6 months
• No neurological disorders
• Not taking medications affecting balance
• Exclusion Criteria: Body Mass Index (BMI) > 25
• History of orthopedic surgery
• Impaired lower extremity joint range of motion
• Inability to complete the test protocol
• Measurement errors or missing data

Healthy female volunteers between the ages of 18 and 35 years were recruited from Ankara Yildirim Beyazıt University. Participants had no recent orthopedic injuries, no neurological conditions, and were not using medications that could affect balance.

It is not yet determined whether individual participant data (IPD) will be shared. Decisions will depend on future institutional policies and publication requirements.