It is a problem both men and women struggle with: working out the so-called glamor muscles - the biceps, the abdominals, the glutes and hamstrings - and ignoring everything else. Unfortunately, focusing so intently on building strength in some parts of the body results in imbalances that can cause injury and pain, ultimately hampering overall progress.

In the upper body, shoulders are frequently subjected to improper training or else no training at all. If you are guilty of overlooking your shoulder muscles, here are a few reasons you need to devote at least one workout a week to your delts as well as a few plans to address and prevent pain in the future.

The Most Complex Joint in the Body

You likely remember that there are several different types of joints throughout your body: the hinge joint of your elbow and knee; the pivot joint of your ankle and neck; and the saddle joint of your thumb are just a few. While beginner-level anatomy courses often classify the shoulder as a ball-and-socket joint, like the hip, it is actually much more complex than that.

If your shoulder were merely a ball-in-socket, the movement of your arm would be severely restricted. Consider the way dogs and cats can’t rotate their front legs up and back or the way your legs can’t move in an arc like your arms. This is because your shoulder is a combination of ball-in-socket, where your arm and collar bones meet, and gliding, where your scapula floats over your back muscles. The combination of these two types of joint allows you an outstanding range of motion - but also has a greater opportunity for injury.

Common Causes of Shoulder Pain

Because your shoulder is so complex, it is easy to injure the small muscles, tendons and ligaments holding it together. Here are a few reasons your activity (or lack thereof) might be causing you pain or discomfort:

Rotator cuff tendonitis. This is the most common cause of shoulder pain by far. When the shoulder is subjected to certain movements, the tendons holding the rotator cuff together can become inflamed. It is best to spend time avoiding your typical shoulder workout and trying other shoulder exercises - or else resting the shoulder until the tendons heal. Otherwise you might tear your tendons, which requires much more extensive therapy and recovery.

Adhesive capsulitis. More commonly called "frozen shoulder," this condition is marked primarily by an inability to move you shoulder as normal. This doesn’t occur out-of-the-blue; the connective tissues in your shoulder thicken and become inflamed over time, usually from disuse and poor posture. However, other conditions, such as diabetes and thyroid problems, can also cause this issue. It takes roughly a year and a half to completely thaw a frozen shoulder, but physical therapy can reduce that to a few months.

Pinched nerve. Sometimes, a pinched nerve in your neck can lead to discomfort in your shoulder. To ensure this isn’t the problem, you should ask your doctor about nerve pain in your shoulders and seek appropriate treatment from a pain clinic near you.

Shoulder bursitis. The bursa are fluid-filled sacks beneath joints to ensure smooth movement of bone and muscle. However, when you perform the same movements repeatedly, the body responds by sending more fluid to the bursa, causing them to become inflamed. Often, bursitis goes away with rest and ice, but in some cases, inflamed bursa need medical intervention.

The Right Workouts for the Shoulder

Unlike many of the glamor muscles, which tend to prefer heavy weight and low reps, the comparatively delicate components of the shoulder will crumble under too much weight. Additionally, it is important to avoid focusing too heavily on one type of lift, like the shoulder press, as doing so can trigger many of the above conditions.

Instead, you should build a well-rounded shoulder workout, which should impact all the different elements of your shoulder. Shoulder muscles respond best to light weight and high reps, and different rotations in your arm will change how your shoulder moves and feels. Consider the following shoulder-safe exercises to integrate into your next shoulder day:

• Neutral grip overhead press. Overhead presses are the most dangerous movement for your shoulder, but they also build strength fastest. The neutral grip, with your palms facing one another, eliminates some of the risk, as does choosing a medium weight.

• Face-pulls. The rear delts are the most difficult to reach with exercise, so face-pulls, which utilize cables or resistance bands to work the back of your shoulder almost exclusively, should always be on the docket.

• Flies. Flies are some of the most versatile shoulder exercises because you can modify height, grip, duration, rep-range and more to perfectly target different parts of you shoulder. You can even sit or lie down to perform flies, which are excellent options for those with other injuries or disabilities.