In Short

Because the rectum only empties completely in a certain body position. Sitting alone isn’t enough.

What We’ve Been Sold as Normal

That you just sit down, strain, and you’re done. That posture is beside the point. And that straining is part of it when things don’t work right away.

The Honest Explanation

When you sit upright, the anorectal angle stays kinked. The sphincter doesn’t relax completely. Stool has to pass against resistance. A slightly raised foot position changes the angle, reduces muscle tension, and allows emptying without pushing. The bowel follows anatomy, not habit.

What You Often Hear – and What’s True

“The body sorts that out on its own.”
It can only work with the right mechanics.

“Straining is normal.”
Straining is a workaround for the wrong posture.

“It doesn’t make much difference.”
The angle decides between resistance and passage.

“It only affects people with constipation.”
Even with regular bowel movements, some residual pressure often remains.

Putting It in Context

Your sitting posture determines whether emptying is efficient or a strain. Ignore posture, and you force the body to compensate.