Some of the most effective hip flexor exercise I found in my many years of Pilates work to be those that focus on stabilizing the pelvis while working the deeper hip flexor muscles.
The purpose of doing exercises for the hip flexors and working to keep these muscles strong is because they are important in how we stand, walk, and move all day long.
If the hip flexors are weak it hinders our ability to lift our legs high enough to walk strong and steady and so we shuffle along.
If our flexors are tight it causes us to stoop forward and lose our posture and balance.
One of my favorite exercises to stretch or open the hip flexors while simultaneously strengthening and stretching the hamstrings on the other leg is the Reformer exercise "Eve's Lunge" as shown to the right here.
Make sure you do hip stretching exercise, strengthening your hip joint, and working your hip flexors routinely because it is so important to our posture and our ability to stand upright and walk and move with ease.
Most of these exercises are from a side lying position, which you can do all of these standing as well to help increase your balance and challenge you further.
Pilates Side lying front and back kicks – Position yourself lying on your side with hips and shoulders stacked over each other, legs are angled slightly forward.
Keep your waist long and pelvis stable. Begin swinging your top leg forward and back at hip level keeping it long and extended. Repeat on each side for 10 repetitions.
Add a bicycle motion to this one for more hip flexor exercise. In the same position pulling the knee up to your chest and then straightening the leg and swinging it around back.
Lying on your back with your head and shoulders down or lifted up to get more abdominal work.
Pull one knee in to your chest and extend the other leg long feeling the hip open up as the abdominal muscles pull in and flatten.
Switch and repeat for about 8-10 repetitions inhaling and exhaling as you switch.
Lying on your back with one leg extended along the mat, torso and leg anchored, extend the other leg up to the ceiling and just under a 90 degree angle.
Circle the leg (thigh) around in the hip socket only as big of circle as you can keep the pelvis and hips still and buttocks anchored to the mat.
Repeat for 8-10 circles each direction.