Are an ab wheel and plank exercises a good replacement for the good old but boring crunches? What effects are better and what it cannot replace?
The ab-wheel and products like it can give you much faster results than crunches and sit-ups alone. I would advise that you have to have almost perfect form when using wheel type products and must hold your abdominal muscles tight when pulling and pushing as well as focusing on maintaining a solid posture and working slowly. It is easy to hurt yourself when using these types of aides, I would not recommend them if you are not already in fairly decent shape with good to very strong arms, chest walls, abdominal muscles and supporting lower back musculature. They can be very challenging, consider first a sit-up bench. They are designed for ergonomics and with some care taken can easily give you the same results as well as offering the options to add weight on your chest or in your hands and being able to target "spare tires". As far as planking goes if you are not attempting very dangerous places to plank then it is always a good exercise for any spare time. I find in between television programs and during commercials its a good time killer. Always keep your core tight, back straight, and work on breathing and maintaining as long as possible.