❌ Lying Tricep Extension Mistake (DON'T DO THIS!) When performing lying triceps extensions, keeping your upper arms vertical causes the barbell to land on your forehead, limiting your range of motion. It also eliminates tension on the triceps at the top of the movement when the barbell is directly above your shoulders. Instead, angle your upper arms slightly back so the barbell moves behind your head. This not only increases the range of motion but also keeps constant tension on the triceps whil