crunches with wrist-weights on your hand to build more

[Alave 1957]

You can also try to do chair resistance.Formula 41 Extreme Cardio exercises do not help directly in building strong muscles. That is why many muscle building gurus advice not to do cardio. But there is a big indirect benefit in doing cardio exercises. Cardio exercises increase your overall stamina so you can do strength training for longer time and build muscles in shorter period of time.http://www.strongmenmuscle.com/formula-41-extreme/