Six hip flexor muscles are in your body. The most important are the iliopsoas, which are two muscles, the psoas major and iliacus, and are situated deep in the abdomen and the rectus femoris, part of the quadriceps muscles on the thigh. Tightening the hip flexors bends the hip in the front. When the hip flexors lock up or lose strength so that you can't bend your hip, you might have an injury to those muscles or the hip joint.
Hip flexor muscles can lock or lose function because of overuse or repetitive motion that gradually causes increasing strain. A sudden forceful contraction, such as a sudden kick, falling or pivoting at the hip, can cause a strain or tear to hip flexor muscles. Trauma, such as a direct blow or kick, being tackled or suffering an auto accident, can directly damage them. The hip flexor muscles can tighten in response to an injury to the hip joint, splinting the damaged area to protect it from movement or further damage. If you are having trouble with hip flexors, the first step should be an accurate diagnosis from your doctor.
Treatment begins by resting the joint so the muscles can heal. Use ice to reduce pain and inflammation. You can use an ice pack, wrapped in a towel, for 20 minutes several times a day on the injured area. Muscles locking is a sign that they are suffering from overuse. Continuing to exercise with strained muscles, even if they don't hurt much, can lead to further damage and loss of function.
Balancing the muscles
After the acute stage, you can begin retraining your muscles. Stretch the iliopsoas, gluteus maximus, quadriceps and hamstrings so that they are all balanced and flexible. Imbalance in muscles, with some tighter than others, leaves you more at risk for injury. Maintain balance between the right and left legs, also, so that they are used equally, and equally strong and flexible. Use manual therapy such as sports massage or trigger point massage to break up fibrotic adhesions and scar tissue in your muscles and along the iliotibial band.
Warm up before exercise, competition or stretching. Walk for five to 10 minutes until your muscles all feel relaxed and warm. Take breaks to avoid overuse and allow your muscles time to recover from exertion. After intense exercise or sports, apply an ice pack for 20 minutes to the hip flexors even if they don't hurt. Ice helps to reduce inflammation and swelling.