When pelvic muscles are fluid, contractions do what they're supposed to do - bring my beautiful baby to me. When I'm rigid, the rushes of energy work harder and less effectively.
Relaxed = minimized pain, focused energy
Tense = increased pain, scattered energy
By relax, I don't mean nap on the couch. It's intense work - it's labor. Gritting my teeth and clenching my jaw only makes labor harder though. This is not a labor like straining to lift a heavy box. This is an effort of opening to an elemental force rushing through me.
A wave cascades, and I focus. Open my mouth to slack my jaw. Dip chin. Touch forehead to smooth creases. Eyes, cheeks ... relaxed.
The face is visible and touchable. It's more challenging to imagine the pelvic muscles. And just thinking "I should relax" probably won't work. I release tension from each specific part of my face.
Think and touch and maybe speak "I'm relaxing my jaw." Try it even before labor starts.
More about relaxing: Here's about positions and how to feel as comfortable as possible. And the science behind it and practical exercises.