2. Tricep Extensions
These are perhaps the best back-arm exercises you can do. Place a dumbbell on the ground near the head of a bench. Lie flat on your back on the bench. Reach back over your head, grab the end of the dumbbell with both hands, and lift it a few inches so that your arms are at a 90 degree angle and one side of the dumbbell is hanging towards the ground. Use your triceps to straighten your arms, thereby lifting the dumbbell upwards.