CHARLESTON, W.Va. -- Dear Cindy,I hope you can help me with a problem I have that keeps getting worse. The muscles that go between the top of my thighs to my waist on each side are very tight. It affects my posture and causes pain in my hips. I am not very active but I do walk some on the weekends. I am an office secretary and spend a lot of time sitting in front of my computer. I feel like I need to stretch, but am not sure how to go about it and don't want to do the wrong ones. -- SandyDear Sandy,You are describing the hip flexors; tight hip flexors are extremely common in the running and cycling community because the movement they do is repetitious. No movement at all, however, can also wreak havoc with the body.We are learning more each day how sitting for long periods can be detrimental to our health. People sitting in a chair for more than six hours a day increase their chances of increased blood pressure, high blood sugar and abnormal cholesterol levels, and also open the door to hip and back issues.Hip flexors are the muscles responsible for flexing the hip or drawing the knees to your chest, as well as moving your legs front to back and side to side. Habitual sitting causes the hip flexors to tighten and shorten, reducing the suppleness needed for a healthy hip joint.Not that simpleThe hip flexors are always singled out, but actually a group of muscles is to blame. They include the iliopsoas, rectus femoris, sartorius, tensor fasciae latae, adductor longus and brevis, pectineus and gracilis. Our muscles rely on and support others. No muscle is an island, so to speak, so you must come at these muscles from different angles to counteract the effect of sitting for hours on end.Get upThe first and best thing to do as you work at your desk is to take a break at least once an hour. Get up and get out of that seated posture. Lift your chest, pull back your shoulders and head and lean back gently. This is extremely helpful to offset the position these muscles stay in as you sit.Loosen upTo release the tension built up in the muscles, you need to spend a few minutes each day stretching to elongate them. This will ease the pain in your hips, and may also prevent future injury because this pain can easily lead to pain in your back.The American Council on Exercise, a leading educator of fitness professionals, recommends and describes the following three stretches for anyone sitting for prolonged periods. Hold and breathe through the stretches for 30 seconds and, if possible, do these twice daily.Stretch 1: Kneeling hip flexor stretchBegin in a single-leg kneeling position with the right foot in front and kneeling on the left knee. Maintain a neutral spine and contract the left glute to stretch the left hip flexor. If you're able, deepen this stretch by gradually shifting the hips forward.Stretch 2: Piriformis stretchBegin in a hands-and-knees position, placing the hands underneath the shoulders and the knees underneath the hips. Cross your right foot over your left and shift your hands over to the right. Gradually begin shifting your weight over to your right hip, lower the hip toward the floor until you feel a stretch. Resist the temptation to shift the glutes back and sit toward the heels.Stretch 3: Quadratus lumborum stretchBegin on your back with your feet on the floor and knees toward the ceiling, with the arms extended out to the sides of the body, palms facing up. Cross the right leg over the left leg and slowly lower both legs to the left, holding this position for 30 seconds. Keeping the legs crossed, slowly move the legs to the center and then lower the legs to the right.Cindy Boggs, wellness presenter and author, is an ACE-certified instructor/trainer. Send your questions about fitness, training or health to firstname.lastname@example.org. Look for her award-winning fitness advice book, "CindySays ... You Can Find Health in Your Hectic World" on her website, www.cindysays.com.