The hip flexors are made up of a group of muscles including the iliacus, psoas major, rectus femoris, and sartorius. Without diving into a full anatomy lesson, these muscles are responsible for swinging the leg forward when you are running. If there is an imbalance in the mobility of this grouping of muscles it can affect a person's gait, which may negatively impact running economy.
The hip flexors often become tight and agitated from sitting too long at a desk or riding in a vehicle. Being mindful to standup every 45min along with completing a short mobility routine (such as the one highlighted below) can go a long way to reducing discomfort and improving running efficiency.
Mobility Routine for Hip Flexors
by Dr. Sophie McDonald - United Sport Solutions
Begin with with hands on hips with your pelvis tucked. Start with 10 forward rocks. Lean forward until you feel light pressure through the front side of your back leg, near your groin area. Repeat 10x on each side.
Extend both arms over head. Lean forward until you feel light pressure through the front side of your back leg. Hold this position x 30 seconds. Repeat on the other leg.
Start with one leg extended out to the side. Slowly shift your weight back onto the bent leg. Hold briefly before returning to the start positioning. Repeat 10x then switch to the other leg.
Start positioned on all fours. Arms and legs should be set just outside of shoulder width. Shift your weight back towards your heels. (Modified childs pose) Hold briefly then return to the starting position. Repeat 10x.
Start with one leg positioned at 90 degrees out to the side. Shift your weight towards that leg until you feel a light stretch on the inside of your leg. Hold briefly before returning to the start position. Repeat 10x each side.