... to keep the back in proper alignment.
Sub-conclusion/Premise ... to keep the back in proper alignment.
Let's contradict ... to keep the back in proper alignment.
As you ... in keeping the back in proper alignment (posture, genetics, etc).
... gap in the relationship between proper alignment of back and ... between balanced muscle developed and proper alignment of back, but ... sufficient/enough to guarantee the proper back alignment? No, its ... someone not to have the proper alignment of back.
...
Nice! That's a huge milestone! Take a moment to bask in the glory, then back to work. Now that you've proven you can do it, time to really up your game to. Definitely not a fluke (assuming proper testing conditions), so just don't let up!