Kneel on one knee beside the free end of a landmine barbell, hold the end of the bar in one hand with your palm up and brace the back of that upper arm against your inner thigh.
Curl the end of the bar up toward your shoulder, keeping your upper arm pressed against your thigh.
Squeeze your biceps at the top.
Lower the bar slowly to full arm extension, finish your reps and switch arms.
Form tips
Keep your upper arm still; only your forearm moves.
Hold the end of the bar securely so it doesn't slide in your hand.