Prolonged sitting and activities like running or cycling can lead to tight hip flexor muscles and a variety of skeletal imbalances. Think: if you only cycle for exercise, certain muscles in your legs will get stronger (in a lot of cases you overwork these muscles) yet your core and outer hip muscles might get weaker from lack of engagement. So what? Well, these muscle imbalances often lead to skeletal imbalances and injuries down the line. If you have particularly tight hip flexors, your body will start to create an anterior pull on the pelvis (anterior pelvic tilt). You can identify an anterior pelvic tilt if your belly protrudes slightly in the front while your butt sticks out in the back (what some people refer to as “duck butt”).
Exercise therapy is effective in decreasing pain and improving function for those with chronic low back pain.[50] It also appears to reduce recurrence rates for as long as six months after the completion of program[61] and improves long-term function.[57] There is no evidence that one particular type of exercise therapy is more effective than another.[62] The Alexander technique appears useful for chronic back pain,[63] and there is tentative evidence to support the use of yoga.[64] Transcutaneous electrical nerve stimulation (TENS) has not been found to be effective in chronic low back pain.[65] Evidence for the use of shoe insoles as a treatment is inconclusive.[51] Peripheral nerve stimulation, a minimally-invasive procedure, may be useful in cases of chronic low back pain that do not respond to other measures, although the evidence supporting it is not conclusive, and it is not effective for pain that radiates into the leg.[66] 

The hip is a basic ball-and-socket joint. The ball is the femoral head—a knob on the top of the thigh bone—and the socket is an indentation in the pelvic bone. There is cartilage lining the joint (called the labrum) and ligaments that attach the pelvic and thigh bones. Numerous muscles attach around the hip, too, moving the joint through the basic motions of flexion (bending), extension (extending the leg behind you), abduction (lifting the leg away from the body), adduction (moving the leg inward), internal rotation, and external rotation.
To avoid hip flexor pain, you should pay more attention to these muscles, Dr. Siegrist explains. When you are seated, your knees are bent and your hip muscles are flexed and often tighten up or become shortened. “Because we spend so much of our time in a seated position with the hip flexed, the hip flexor has the potential to shorten up. Then, when you are in a hurry because you are running to catch a bus or a plane, or you trip and fall, the muscle could become stretched. Here’s this stiff, brittle muscle that all of a sudden gets extended, and you could set yourself up for strain or some hip flexor pain.” Click Here to Learn Unlock Hip Flexors