Single-Arm Overhead Triceps Extension — Common Mistakes 1) Elbows Flaring Out Letting your elbow flare turns the movement into more of a press, shifting tension to the shoulders and increasing stress on the elbow joint. Fix: Keep your elbow tucked and your upper arm as close to vertical as possible. 2) Upper Arm Drifting Forward/Back If your upper arm swings around, the triceps lose consistent tension and your shoulders and lats start taking over. Fix: Keep your upper arm locked in place and sta