That is a result of a pose you've chosen.
The game imposes certain poses that make things harder and envoke at the start of the game. For instance, since its common, I'll intentionally skip working out my arms. Eventually a forced pose selection appears which is "Eliminate Weakness" + stats, but remove arms.
That Remove-Arms means you have no muscles in your arms. They were transplanted into your other muscle groups via Backstreet surgery. The counter to this is a special card called "Heavy Cards" which gains your arms for each card played regardless to workout.
With my arms removed and weak, they wind up being the strongest muscle by the time I reach absolute unit.