context: You might not be Atlas, but your shoulders still carry a lot of weight. If it weren't for them, you wouldn't be able to pitch a game-winning home run, shovel snow off your front walk, or even comb your hair. The shoulders' ball-and-socket design gives you great range of motion, but at the expense of stability. The shoulder socket is shaped like a golf tee: fairly flat on top, so the ball of the upper arm bone can easily slip out of it. That instability is why the shoulder joint gets dislocated more often than any other joint in the body. When you lift weights every day or pitch every weekend, you can put a lot of wear and tear on your shoulder muscles, tendons, and joints. This is especially true if your form or technique is off. Repetitive stress can lead to tears and other injuries, which can take you off the playing field and leave you in serious pain. You'll want to be aware of the most common shoulder injuries -- how to spot them and what to do about them. What it is: Your rotator cuff is the set of four muscles that sits around the ball of the shoulder joint and allows the shoulder to move. How it can get hurt: Sports that involve lifting your hands over your head -- like pitching in baseball, swimming the freestyle or butterfly stroke, serving in tennis, and weightlifting -- can cause the top part of the shoulder blade to pinch the rotator cuff muscles. Doctors call this âshoulder impingement.â Repetitive motion in sports can also overload the tendons of the rotator cuff. Over time, they can swell and get inflamed. Doctors call this tendinitis. If you ignore the pain and keep swinging that golf club or tennis racket, the tendon that connects the rotator cuff muscles to the ball part of the joint can eventually tear. What you'll feel: Pain is the main symptom of a rotator cuff injury. The pain gets worse when you raise your arm, and you might hear a click or popping sound. Eventually, the shoulder will hurt even when you're not moving it. A rotator cuff injury can limit your shoulder movement and cut your strength. Treatment: Your doctor may suggest that you rest your shoulder for a few days, then start rotator cuff stretches and exercises so that this area gets stronger and moves well. Don't lift anything above shoulder level until the injury heals. An anti-inflammatory medication or corticosteroid injection may help bring down swelling and ease pain. If the pain and weakness don't improve, you might need physical therapy or surgery. If you do need an operation, the type of procedure will depend on the size, type, and location of the tear. It may take several weeks or even months for a rotator cuff injury to heal. Prevention: Exercise your rotator cuff muscles to keep them strong and improve your range of motion. Be careful when you play sports like golf and tennis that use the same repetitive motions. Switch up your game once in a while. And stop whenever you feel pain. What it is : The AC (acromioclavicular) joint is where the uppermost part of your shoulder blade -- a structure called the acromion -- meets your collarbone. When ligaments connecting the acromion and collarbone get torn, you've got a separated shoulder. How it can get hurt : You might get hit hard in the shoulder or fall on an outstretched hand. What you'll feel: Pain in your shoulder. You might also see a bump on top of the shoulder where it's separated. Treatment: You'll need to see your doctor if you think you might have an AC joint injury. You will probably need to wear a sling to keep your shoulder still. Ice the area for about 20-30 minutes every couple of hours to cut swelling. Take acetaminophen or a nonsteroidal anti-inflammatory drug like aspirin, ibuprofen, or naproxen to help with the pain. Prevention: Do range-of-motion and strengthening exercises. Gradually increase the weight and number of reps to strengthen your shoulder. What it is : A dislocated shoulder happens when the top of the upper arm bone (the âballâ) slips out of its socket. The ball can slip forward, backward, or downward. Before you fully dislocate it, the shoulder might feel like it's starting to go out of place. That's called instability. When the shoulder slips only partway out of the socket, doctors call that âsubluxation.â How it can get injured : A strong hit to your shoulder on the football field or ice hockey rink can pop the ball out of its socket. You can also get a dislocated shoulder if you rotate your shoulder joint too far, like when you're serving in volleyball. What you'll feel: You can feel when your shoulder pops out of place. The pop will be followed by intense pain. You might also have swelling, bruising, and weakness in the arm. Treatment: Don't let anyone work on your shoulder unless you're sure they are trained and have experience in doing this. Otherwise, it could make matters worse. Instead, see your doctor, who may give you a sedative or pain medicine before sliding your upper arm bone gently back into its socket. You'll have to keep the shoulder still for a few weeks afterward in a sling. If your shoulder is being stubborn and it won't go back in place, you may need surgery to move the joint. Surgery can also repair torn ligaments or tendons in your shoulder. Prevention: Ask your doctor to see when and how much you can use your shoulder. Once you've fully healed, she may suggest that you start exercising your shoulder to keep it flexible. Slowly add in weights and resistance bands to boost your shoulder strength if your doctor or physical therapist approves. If your shoulder has been dislocated before, ease off on sports or other activities until your doctor clears you to return. That can take a few weeks. Anyone who's had a dislocation once has a good chance of it happening again. If you play a contact sport and your doctor clears you to get back to it, wear shoulder pads or other protective gear.