Front thigh muscle tightness can be caused by such issues as poor posture, stiff hip joints, a stiff spine or too much neural stimulation in the thigh and hip flexors. Different causes of muscle tightness require different approaches to lengthen and relax the area; there are no cookie-cutter workouts that fit every situation.
When muscle fibers contract, the microscopic contractile proteins — actin and myosin — cross each other and shorten the muscle. When there is too much neural stimulation to the muscle -- either because you're overworking a muscle or because you have a nutrient imbalance -- the muscles stay contracted. This muscle cramp can lead to joint stiffness that prevents your hip joint from extending when you run, walk or climb stairs. Without proper hip extension, your stride will not allow you to move faster without risking back pain or knee pain. Poor hip extension also causes your lower back to hyperextend to compensate for the lack of movement in the hip joint.
An elevation postural deviation is diagnosed when one side of your body is higher than the other, such as a shoulder or one side of your pelvis. If one side of your pelvis is higher than the other side, then the shoulder on the same side of the raised hip will hike up. This causes the muscles and tissues in the lowered hip and shoulder to compress downward, causing tight hip flexors and a tight leg on one side.
Stiff Hip Joints
Hip stiffness may render you unable to move your hip joints in all ranges of motion, including rotation, flexion and extension. This is often caused by sitting too much and not moving enough. For example, when your hip flexors get tight from sitting and your buttocks and deep abdominal stabilizers get weak from lack of use, this tightens your hip flexors, which pulls on the lumbar spine and the upper thigh and causes your front thighs to get tight.
Stretching your hip flexors and strengthening your hip and spine will prevent your thigh muscles from getting tight and stiff. This reduces the amount of neural stimulation to your muscles and connective tissues, allowing your hip to open up more. As a rule of thumb, moving regularly with less sitting will decrease front thigh tightness.
If you have an elevation deviation, you can perform corrective exercises that balance your body and improve your pelvic, spinal and shoulder alignment. The types of exercises you should do will depend on the severity of your deviation, your physical condition and your pain level.