For runners, the number one affect of prolonged sitting is tight hip flexors. They originate from the back and attach to the hip. The hip flexors are located a couple inches outside the belly button. Tightness of the hip flexor limits your stride length, and contributes to low back pain, knee pain and even foot pain. For example, if your left hip flexor is tight it will limit the right leg’s ability to reach forward, resulting in a shortened stride or forcing the leg to cross midline. Since the hip flexors attach to the spine, tightness will pull the spine forward leading to bad alignment. Lastly, it can lead to prolonged pronation of the foot.
Here are 2 different techniques on how to stretch the hip flexors. AND on 3Drunner, I'll show you how to stretch them in all three planes of motion.
Hip flexor stretch #1
Hip flexor stretch #2
For each stretch perform 10 -15 movements per plane of motion depending on how tight you feel.
After stretching, your hip muscles may feel a bit funny, loose and wobbly. This feeling is due to the newly stretched muscles not knowing how to control movement. They have been “sleeping” for some time and need to be retrained. In running, the hip flexor muscles are used eccentrically ( meaning they lengthen) so it’s better to work them eccentrically.
Lunge with overhead reach
Perform 5-10 of each of the lunges.
Here's a bonus video on how to mobilize your hip flexors.
Using a ball to roll on the muscle is like getting a massage. This will enhance the stretches and mobility exercises.
Hip Flexor Roll Out
A minimum of 2 minutes per side.
Hope this helps.