One of the largest and most powerful groups of muscles in the human body is located in the buttocks. Consisting of the gluteus maximus, gluteus medius and gluteus minimus — collectively known as "the glutes" for short — these muscles are important to most of the body's active movements. If they are weak or underdeveloped, your posture can suffer.
The largest muscle, the gluteus maximus, is part of your body's stabilization system known as posterior oblique sling, along with the latissimus dorsi and thoracolumbar fascia. When your glutes aren't doing their job, the latissimus dorsi overcompensates, pulling the torso and shoulders out of proper position.
Read More: How to Strengthen My Glutes
An Antagonist for Every Agonist
Muscle groups are designed to work in pairs. When you bend your arm at the elbow, for example, your biceps contracts to create the movement and your triceps relaxes. When you straighten it, the opposite happens. The muscle that's contracting is referred to as the agonist, while the one that relaxes is the antagonist. It's important that the two be balanced, or the body will have to compensate. In the case of your glutes, the antagonist muscles are your hip flexors. If they're stronger than your glutes, they can pull your pelvis into an unnatural alignment, known as anterior pelvic tilt, causing pain and posture problems.
The word posture might conjure up a mental picture of long-ago schoolgirls standing and walking with books balanced on their heads. Correct posture is more than standing straight, though that's a large part of it. When you are standing, an observer should be able to draw a mental line vertically from your earlobe through your shoulder, hip, knee and ankle. Your abdominal muscles should be tight, your shoulders square and your chin up, whether you are standing or sitting. If this isn't the case, you can regain proper posture by conscious effort and strengthening the gluteal group.
Read More: The Advantages of Good Posture
Strengthen Your Glutes
To help fix your posture, work on strengthening your glute muscles through a variety of exercises. As the moves start to get easier, add or increase the amount of weight you're using. Some exercises to incorporate into your regular routine include: