Which of the following could indicate a lack of proper mechanics during a biceps curl?

A lack of proper mechanics during a biceps curl can often be indicated by elbow flare. When the elbows flare out during this exercise, it suggests that the movement is not being performed correctly, which can lead to improper activation of the biceps and potentially strain other muscles or joints. Proper technique requires that the elbows remain close to the torso, ensuring that the biceps are the primary muscles engaged during the curl, while also reducing the risk of injury.

Muscle soreness can occur from effective workouts that involve necessary strain, joint clicking may happen due to normal joint movement or minor instability, and post-exercise fatigue is a common response to physical exertion. However, these factors do not specifically reflect improper mechanics in the same direct manner as elbow flare does during a biceps curl.