11.   These exercises are good for making your stomach muscles nice and firm.

12.   Tighten your stomach muscles and hold for three seconds.

13.   Using his arms and stomach muscles, trying to keep his chest still, he sat.

14.   You can do exercises to strengthen your stomach muscles.

15.   These exercises will help to tighten up your stomach muscles.

16.   These exercises will strengthen your stomach muscles.

17.   My stomach muscles are tight.

18.   Lindsey felt her stomach muscles relax.

19.   Her response was a sudden flush of heat and a clutch of desire that abruptly tightened her stomach muscles.

20.   And it was refreshing to work my stomach muscles without doing sit-ups.