Whenever I do situps or abdominal work i have sore lower ribs the next day ??Is there a muscle there ?
Your diaphragm is a large muscle located around the bottom of the ribs. It's what controls your breathing. Are you breathing out when you contract your abs and breathing in when they aren't contracted? If you're trying to breath in when you sit up you may be stressing your diaphragm. If you haven't done much cardio or any sort of activity that involves deep heavy breathing then you're just working your diaphragm more than it is used to.
Try breathing deeply when you're at home. Just focus on expanding your stomach when you breath rather than raising the shoulders. This is good as it will both work your diaphragm if you normally breath shallow and it will provide more oxygen to your body.
ahhhh, ic thanks!