The hip flexors, generally speaking, are the muscles in front of your hip and thigh that bring your thigh forward as you walk or run, in conjunction with other muscles in your legs. During running, the hip flexors raise the thigh and lift the foot off the ground, helping to spring the leg forward into the next step. As well, the hip flexors have an impact on the spine and may help us maintain a proper posture.
Some researchers have theorized that as running speed increases, the hip flexors are one of a few groups of muscles that must generate increased forces to achieve that faster pace. If the hip flexors begin to fatigue during a strenuous or long run, the result can be a “shuffling” style of running, which is inefficient and forces other regions of the body to work harder in order to maintain a certain speed. Strengthening the hip flexors will improve the endurance and power of this muscle group, allowing the runner to maintain proper form.
There are a number of simple exercises that you can incorporate into your routine to gradually improve your hip flexor strength, such as planks, mountain climbers, leg raises, and leg lifts.
Whatever exercises you choose, remember that maintaining good form is essential for maximizing the benefits and minimizing your risk of injury. Always consult your physician, physical therapist, running coach, or other certified sports training professional before incorporating new exercises into your program.