The Use of Two Different Smartphone Applications in Measuring

This study will include healthy volunteers aged 18-25 years. Demographic information will be recorded, and an experienced physiotherapist will mark five reference points on the spine of the participants, starting from the cervical spine and extending to the lumbar spine. Angle measurements will then be taken from these five reference points using a gravity inclinometer, an Android smartphone, and an iOS phone. Measurements will be repeated twice on the same day and twice again 24-48 hours later using three different devices. The accuracy and similarity of the measurements taken with these three devices will then be compared.

Inclusion Criteria: * Being over 18 years of age, * being able to stand and walk without an assistive device, * not having experienced back pain or lower extremity pain in the last 6 months, * and being willing to participate in the study. Exclusion Criteria: * Lack of consent, * lower extremity injuries (dislocation, sprain) within one month prior to measurement, * lower extremity fractures within the last 6 months, * tactile sensitivity that prevents the adoption of a free and habitual posture.