Core strength is important for running, strengthening, and most movement. I include the hip flexors in core training as they play a role. We need to move away from the thought of core training as the just the “six pack” rectus abdominus muscles.
The exercise that I am going to show will involve many of the muscles that make up the core. I like to use mini resistance bands for this. This exercise can be used as a warmup. Psoas holds can also be used as a specific core exercise. One quick note on progression before I share the video. Once you can complete the 2-3 sets of 10 second holds you can increase the resistance of the bands. You can also bring your knees higher toward your chest over the 90 degree angle. That would work the illopsoas. It does not get challenged until above 90 degrees. Be sure to keep your lower back, lumbar spine in contact with the floor or mat.