Hello! I wish to know what exercises are meant for abs. Do pushups, crunches, etc form a part of those exercises? Also, I am a 21 year old guy, contemplating to start with pushups and crunches. Will these affect my height growth? Or do contribute to increase in height?
Pushups, crunches, etc., will not hurt your growth - but it is unlikely you're going to grow much if any at 21 anyways.
You already have abs. The key is to define them. How is your weight? That's the first issue. Drop a few pounds to reveal what you have.
Crunches and walking work. Just get moving. Moderate aerobic activity works.
You can check out our Abs app as well - http://www.steadyhealth.com/ab-workouts-for-men-and-women
We made it in cooperation with two personal trainers (you can see them in the videos) and the app is perfect for shaping the abs. Let us know the results! And don't forget on nutrition.