What observation might indicate that a subject is impaired during the One-Leg Stand test?

During the One-Leg Stand test, observing a subject constantly shifting their weight and losing balance is a key indicator of impairment. This behavior suggests difficulty in maintaining stability, which can result from the effects of substances that impair motor coordination and balance.

The One-Leg Stand is designed to challenge an individual's physical and cognitive faculties. An impaired subject may struggle to keep their leg raised steadily, leading to noticeable movements as they attempt to regain their balance. This shifting often involves swaying, stepping, or using their arms for support, all of which are signs of decreased control.

In contrast, maintaining a straight posture and locking the knees indicate a level of stability and control, while remaining quiet throughout the test does not provide information about the subject's balance or physical ability. Therefore, the observation of constant shifting and difficulty in maintaining balance is a clear sign of potential impairment during this specific test.