The hip flexor is a major muscle group that attaches your femur to your pelvis and lower spine, allowing you to draw your knees up toward your torso and to move your legs back and forth and side to side. In today's modern sedentary society, many people spend a lot of time sitting; while this doesn't really weaken the hip flexor's strength, it can have a devastating effect on the flexibility of this powerful muscle group. Here are some exercises that can help improve the flexibility of your hip flexor.

Lunges are excellent for the hip flexor. They act on the quadriceps, which are a large muscle group that runs along the front of your thigh. While the quadriceps are an independent muscle group, they also form part of the large hip flexor muscle group.

Lunges act to lengthen the psoas and illiacus muscles. The psoas muscles attach your femur to your lumbar spine and form part of the muscles of your abdomen. The illiabus muscles run beneath the psoas muscles to attach your femur directly to your pelvic bone.

Both low and high lunges work on the hip flexors. High lunges, performed with the rear knee held aloft, help to strengthen the flexor muscles, but they also help to make hip flexor muscles more flexible. Low lunges, performed with the rear knee on the floor, help to lengthen the muscles of the hip flexor considerably.

While hamstring stretches don't actually act on the hip flexor muscles themselves, stretching here is an important part of developing healthy flexibility in your hip flexors. If your hamstrings are tight and short, while your hip flexors are long and supple, your tight hamstring muscles will exert a posterior force on your pelvis, leading to gait and postural problems. Conversely, if your hip flexors are tight and short but your hamstrings are long and supple, your tight hip flexors will cause an anterior pelvic tilt, leading to lower back pain and other problems. That's why it's important to stretch both the hip flexors and the hamstrings equally.

Pigeon Pose is a restorative yoga pose that provides a deep stretch in the gluteal muscles. It's important to develop flexibility in these muscles for much the same reason as it's important to develop flexible hamstrings. Tight gluteal muscles can create postural and gait problems when combined with long hip flexors.

Full Pigeon Pose can be difficult for beginners to perform. Luckily, there are a number of easy, comfortable variations of this pose that can help you reap its benefits.

The muscles of your inner thighs make up an important part of the hip flexor group. Wide legged forward bends stretch the muscles of the inner thighs. Yoga poses like Bound Angle Pose also help to open and lengthen the muscles of the inner thighs and groin. Triangle Pose and Garland Pose are also great hip openers that work on the groin.