S-Posture (Arched Lower Back)
What is actually happening
Somebody told you to stick your chest out and keep your back straight, and your lower back overdid it. The pelvis tips forward, the belt buckle points at the ground, and your lower spine arches into an S over the ball. It looks athletic in the mirror. But that deep arch switches your core off, and the big muscles that should power your turn never enter the swing.
What it costs you
With the core off, your body loses its brake on the backswing. The weight never fully loads into your trail side, the upper body tips toward the target at the top, and the strikes run thin while distance quietly leaks. The arch also grinds your lower back on every swing. That's the soreness you feel the next morning.
Tuck your belt buckle up toward your chin a half inch, like zipping up a heavy jacket. Flat lower back, tall chest.
Pelvis-Tuck Rehearsal
Take your address and put your glove hand on your belt buckle, trail hand on your tailbone. Now rock your pelvis through its full range. Tip it forward until your lower back arches hard, then tuck it under until your back rounds. You need to feel both ends before the middle means anything. Settle where the buckle sits level and your lower back feels long, and notice your stomach switch on when you get there. That engagement is the whole point, because an engaged core is what an arched back turns off. Hold the neutral pelvis for five slow half swings, then hit five full 8-irons. Film one down the line and look at the belt line: level, not tilted at the ground. Do the rehearsal at the start of every range session until level is what normal feels like.
Is this the one costing you shots?
Film one swing and the analysis checks for it at every position, on your video.
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