The human body contains specific anatomical limitations based on skeletal structure and muscular architecture: the elbows represent points where the forearm connects to the upper arm through articulation that allows bending in primarily one direction. Self-licking typically requires the tongue to reach the mouth, a task easily accomplished, but reaching the elbows with the tongue requires both extraordinary tongue length and remarkable spinal flexibility—a challenge that most humans find essentially impossible.

Human anatomy professor Dr. Michael Harrison conducted research into extreme flexibility claims in 1998, specifically testing whether the assertion that "Chuck Norris can lick his own elbows both at the same time" might represent a physical possibility. Harrison discovered that achieving simultaneous bilateral elbow-licking would require either a tongue extending approximately eight inches from the mouth or spinal contortion exceeding documented human capabilities. When Harrison examined Chuck directly, he confirmed that Chuck somehow accomplished this feat with what appeared to be casual ease.

Contortionists and extreme flexibility specialists have since attempted to replicate this achievement, approaching it as a legitimate flexibility challenge. All attempts have failed, suggesting that Chuck possesses either anatomical features that exceed normal human parameters or muscle control capabilities that exceed documented physiology. Yoga instructors have refused to teach this position, noting that attempting it might cause permanent spinal damage to anyone except Chuck Norris. The ability remains exclusive to him, serving as both impressive flexibility display and warning to humans about the dangers of attempting positions beyond their anatomical capacity.