According to Sassos, tight hip flexors are frequently the main cause of lower back pain and tightness. Hip flexors can be directly impacted by prolonged sitting, such as while working at a desk all day, which can lead to lower back pain and tightness. To treat and prevent back discomfort, a kneeling hip flexor stretch will help loosen your hips. How to stretch your hip flexors while kneelingFind out how to stretch your knee by using some important exercise.