Spine alignment refers to the correct positioning of the bones in our spine. It means having a straight and balanced spine, where each part is properly aligned with the others. Full definition
Your head should be looking down at the bench for the whole move so that your keep a neutral spine alignment (spine is kept in a straight line). (fitbodyhq.com)
A firm mattress is the best mattress here, as it will keep the body in a position where spine alignment is minimal. (idealhome.co.uk)
Now popular with millions worldwide, the Pilates fitness system focuses on spine alignment, breathing and core strength to improve muscle strength and elasticity. (womenshealthandfitness.com.au)