This course describes hip flexor release and lengthening, commonly referred to as hip flexor foam rolling, hip flexor release with ball, hip flexor stretching, and hip flexor mobility techniques. Although terms like tight muscle, muscle tightness, tight hips, and tight hip flexors are commonly used, it may be more accurate to label these muscles as prone to over-activity (e.g. hypertonic, phasic). Performing hip flexor release and lengthening techniques to increase mobility prior to activation, integration, and strengthening techniques may significantly enhance rehabilitation and performance programs. In practice, the release of the tensor fascia latae (TFL), vastus lateralis, rectus femoris, and adductors, mobilizing the hip joint, and integrating a kneeling hip flexor stretch, active hip flexor stretch, and/or standing adductor stretch, is likely to improve hip mobility and improve the effectiveness of exercises like gluteus medius clams, glute bridges, deadlift touchdowns, etc.