Anchoring and Postural Stability

This study will compare standing balance in adults ages 18 to 50 during normal standing, inward anchoring, and outward anchoring. Anchoring involves standing with the feet wider than shoulder width and trying to pull the legs together or push them apart without moving the feet. Participants will complete all three conditions in a randomly assigned order. A researcher will use a handheld force-measuring instrument at six points on the pelvis to measure how much pressure participants can resist before a foot lifts from the floor. Participants will also rate how stable they feel after each anchoring condition. The first 18 participants will repeat assessments to evaluate measurement consistency. Participation is expected to last 60 minutes, or 90 minutes for those completing repeat assessments.

Inclusion Criteria: * Adults aged 18-50 years. * Able to provide informed consent and independently read, write, and communicate in English. Exclusion Criteria: * History of neurological or vestibular conditions affecting balance, such as stroke, Parkinson's disease, multiple sclerosis, or vertigo, or uncorrected/inadequately corrected visual deficits affecting postural control. * Lower-extremity or spinal injury, orthopedic surgery, or a musculoskeletal condition within the past 6-12 months that may affect balance, force production, or safe participation. * Current pain or dysfunction limiting safe standing or weight-bearing tasks. * Use of medications that may affect balance, coordination, or muscle performance, such as muscle relaxants, opioids, or sedatives. * A cardiovascular or systemic condition that makes participation unsafe, such as uncontrolled hypertension, dizziness, or syncope, or inability to stand independently for the duration of testing.