A client demonstrates lower crossed syndrome.

Lower crossed syndrome (LCS) is a common postural distortion characterized by an anterior pelvic tilt, lumbar lordosis, and overactive/shortened hip flexors and erector spinae, with underactive gluteals and abdominals. The NASM CPT7 Study Guide identifies the rectus femoris—part of the quadriceps and a hip flexor—as one of the shortened muscles in LCS.

Static stretching is recommended for overactive muscles to restore proper length-tension relationships. The gluteus maximus and medius are typically underactive in LCS and should be strengthened, not stretched. The rectus abdominis is usually lengthened and underactive. Therefore, in LCS, the rectus femoris should be statically stretched.