I currently do 300-500 crunches a day. Its usually the simple crunches with the feet flat on the ground. I'm looking for some new exercises that involve tightening your stomach and your chest. I don't want to develop big pecs either with these exercises I just want to keep my chest nice and tight.
As you can see, there are many opinions on what to do and not to do. You say you are currently doing 300 -500 crunches a day. I would say you have mastered that movement at the current volume and tempo you are using. The abdominals are a complex of muscles that are usually at work when you are standing or lying down and exercising.
You are attemtping to keep your abs and chest muscle mass perserved, while gaining more definition or "tight" look. Understand first and foremost, there is no such thing as spot reduction (at least not proven). So, you will not just lose fat in one area of the body because you work it harder than others. Like a few people have already said you must aim for simply reducing overall body fat.
The quickest way to lose body fat is with proper nutrition, full body training (circuit or undulating proven to be superior....just google undulating periodization or circuit training to get more info) and cardio
A few tips for training for a solid and lean body:
- Do most exercises standing up or holding yourself up against gravity (squats, deads, pushups, pullups, dips)
- Train your back (posterior) muscles harder than front (anterior) muscles (so do more pulling exercises than pushes)
- Do cardio after weight training or on a separate day. If cardio needs to be done before, try to do it 4 hours prior to training if possible.
- Change volume and tempo more than you change exercises
- Look into HIIT type training as well
Hopefully this helps out a bit.
Goodluck