What physical action can indicate impairment during the One-Leg Stand test?

Swaying is a significant indicator of impairment during the One-Leg Stand test. When an individual is instructed to stand on one leg, swaying suggests a lack of balance and coordination, which are often impaired by alcohol or drugs. This swaying can manifest as side-to-side or forward-and-backward motion, and it demonstrates the subject's difficulty in maintaining stability, a crucial aspect of this test.

In contrast, other physical actions, while possibly pertinent to overall performance, do not directly measure the same balance impairment that swaying does. For example, stepping forward may indicate a need for stability but does not necessarily reflect intoxication in the same manner as swaying. Keeping the leg fully extended is a requirement for the test and does not indicate impairment but rather proper execution. Maintaining a stiff posture can suggest tension or anxiety rather than balance issues, thus not providing the same clear evidence of impairment as swaying does.