The hip flexor musle group encompasses a number of individual muscles as well as some other major muscle groups. These muscles and muscle groups include:

• The iliopsoas, or muscles of the inner hip, which are the psoas major, psoas minor and the illiacus muscle
• The thigh muscles, rectus femoris and sartorius
• The gluteal muscle tensor fasciae latae
• The muscles of the inner thigh, adductor longus and brevis, as well as the muscles pectineus and gracilis

The hip flexor's main function is to help the hip joints move properly in their full range. The hip flexor helps you draw your leg to your torso, and also helps you move your legs from side to side and backwards. The hip flexor is the muscle group that connects your legs to your torso and lower body, and allows your legs to move in conjunction with your torso. The hip flexor also serves to stabilize your hips and lower body, keeping the joints of your pelvis and lumbar spine strong.

If your hip flexors are overdeveloped, tight, stiff or short, you'll suffer from lower back pain and hip pain. You could experience a limited range of motion in the hips and lower back. That's because tight hip flexors pull your pelvis into an unnatural forward tilt, which in turn pulls your lumbar spine out of alignment, causing lower back pain.

The hip flexor is a major stabilizer of the lower body, so if your hip flexor is too weak you'll suffer from poor balance and postural problems. You may have problems with your hip joints and frequent misalignments in your lumbar spine. You'll have trouble standing and walking for long periods of time, and you may have problems with your gait.

It's important to keep your hip flexors strong as well as flexible. Yoga, sit ups and leg lifts, especially using small weights, are good ways to strengthen your hip flexors. If you can perform leg lifts while dangling from a pull up bar, then this is an excellent way to strengthen your hip flexors. Just remember to keep your spine straight to prevent back injury; if you feel your spine bending as you lift your legs, then you've lifted far enough.

You should also stretch your hip flexors regularly to keep them long, loose and supple. Low lunges (in which you place your rear knee on the floor), butterfly stretches and the Pigeon Pose from yoga are all good ways to stretch your hip flexors.