#1: Straightening Your Arm on Lateral Raises
Lateral raises targeting the middle delt are done with a slight bend in the elbow. The problem arises when the elbow isn’t locked throughout the movement. Too often you see guys with a 90-degree bend at the bottom, but their arm straightens to 180 degrees at the top, especially when they do one arm at a time. Straightening the arm is called elbow extension, and the triceps — not the delts — is responsible for this action. You can’t open and close the elbow joint during execution. Keep it locked in a slightly bent position.
#2: Straightening Your Arm on Rear Delt Exercises
The same blunder involving elbow extension frequently makes its way over to rear-delt exercises, most commonly bent-over lateral raises with dumbbells or cables. When you extend at the elbow, you turn a perfectly good rear-delt exercise into one for triceps. Again the key is to lock your arm in a slightly bent position for the duration of the set. If you’re not getting the hang of it, practice doing the reverse flye on the pec-deck machine, which requires you to maintain a slight bed for the entire exercise.
#3: Positioning Your Hands Too Close on Upright Rows
To target middle delts, your upper arms should travel out to your sides during upright rows. That’s not what happens, however, when you use a close grip. Your elbows are drawn forward as your shoulders are internally rotated. That movement isn’t kind to your shoulder joints. A much wider grip (hands about shoulder width apart) allows your elbows to kick out high and wide, perfect for targeting your middle delts. (The front delts get some work, too.) Even if you’re looking to add variety to your routine, skip the close-grip version.
#4: Neglecting Your Rotator-Cuff Muscles
Sure, you want big shoulders, and that means choosing exercises that target the front, middle and rear delts. However, a smaller group of four rotator-cuff muscles also work in tandem to help stabilize your shoulder joint (and that includes during presses for the chest). As your delts grow stronger over time, and if you’re not also training your rotator-cuff muscles, a strength imbalance arises that makes the rotators much more susceptible to injury and chronic pain. Doing specific rotator-cuff work with extremely light dumbbells, cables and bands may not look impressive, but it’s a necessity for long-term pain-free training.
#5: Going Very Heavy With Behind-the-Neck Presses
Going heavy with your presses isn’t a mistake. That’s how you build size and strength in your shoulders. But when you’re using max weights for very low reps, stick with presses in which you lower the bar to the front of your head. Amateur bodybuilder and sports-medicine doctor Guillermo Escalante, DSc, CSCS warns: “When you lower the bar, the deltoids are lengthening to a fully stretched position, but they’re also at their weakest. The highest risk of injury in any sport occurs when the shoulder is abducted and externally rotated. Loading up a huge amount of weight is just asking for a tear.” Although the joints of some younger bodybuilders may be more resilient, for many others the risk is real. Keep your weights moderate if you’re doing behind-the-neck presses.