Blunder 3: Dropping Your ElbowsA common mistake among beginners is to wave the weights up and down without raising their elbows out to their sides. In that sense, the upper arms don’t go through much of a range of motion, which can kill your middle-delt gains. That’s why you always want to “lead with your elbows” so they go through the full ROM.

When your elbows don’t move much, you essentially negate the benefits of this middle-delt movement. Even though your hand is where it should be at the top, your elbows are still only about halfway up. Note to self: Always lead with your elbows. Blunder 4: Stopping The Motion At Shoulder HeightPeople usually do lateral raises to about shoulder height, even though the middle delt’s range of motion extends further overhead. By continuing up to about 45 degrees above parallel, you can get a bit more contraction out of your middle delts. (You’ll also engage your upper traps a bit.)
When you extend your range of motion above your shoulders, you’ll probably have to back off on weight. You might consider a few heavier sets to shoulder level, followed by a few more with a slightly lighter weight taken about 45 degrees above parallel.

If you have shoulder impingement or pain, it’s probably not a good idea to lift above your shoulders. If this is an issue, talk with a sports-medicine doctor before trying to extend your ROM.
Blunder 5: Locking Your Arms So They’re Completely ExtendedOccasionally, you’ll see someone doing lateral raises with their arms locked out to full extension. At the top of the movement, it looks like the person is trying to form the letter T. This full extension puts a heckuva lot of pressure on the elbow joints. Whatever exercise you’re doing, it’s never a good idea to lock out a joint.