If you've been experiencing lower back pain from performing Romanian Deadlifts (RDLs), pay attention - the solution might be simpler than you think! This specific discomfort you're feeling when you bend over, typically located on either side of your tailbone, is one of the easiest types of lower back pain to address. Here's why and how.

The region causing this pain, close to your tailbone, houses the sacroiliac (SI) joint. This joint is where your spine (sacrum) connects to your hip bones (ilium). One of the critical movements at the SI joint is nutation, where the top part of the sacrum moves forward, causing the pelvis to tilt forward (anterior pelvic tilt). Nutation is crucial for providing stability during activities like lifting heavy weights or bending forward.

However, if your pelvis tilts too much due to tight hip flexors, the sacrum can lose its hold on the pelvis. This displacement can cause a strain on the SI joint and manifest as the lower back pain you've been experiencing.

The usual culprits behind this unnecessary pelvic tilt are the hip flexors. When tight, they pull the pelvis forward, resulting in an anterior pelvic tilt. This tilt affects the position of the sacrum, causing the pain at the SI joint.

But here's your quick fix: You'll need a foam roller. Use it to roll out your quads for a minute on each side. This act helps to relieve some tension in your tight hip flexors. After this, do a couch stretch on each side for a minute. This stretch further loosens your hip flexors, helping to correct your pelvic tilt.

Performing this simple routine can help to reduce the anterior pelvic tilt, encourage proper nutation, and help the sacrum maintain its alignment with the pelvis. This alignment can relieve the strain on the SI joint, thus alleviating your lower back pain.

In conclusion, understanding your body's dynamics, particularly the role of the SI joint and the concept of nutation, can guide you to more effective and less painful workouts. It's crucial to remember that looking after your hip flexors can save you from a lot of lower back pain in your fitness journey.