Who doesn't want toned, six-pack abs? The mountain climber cross-body exercise is one that you should do regularly to shape your body faster. It will help you burn more than just belly fat.
Its important to do effective strength exercises to avoid wasting time in the gym. Work as many major muscle groups as you can so you can do more work in less time. The best core exercises work other muscle groups as well. That is why I recommend doing the mountain climber cross-body exercise instead of the bicycle exercise. The mountain climber is simply a more effective (and safer) fat burning exercise.
Core training is critical and the core is the weakest link for many people. Weak cores lead to back and other trunk-related injuries. The mountain climber will help you strengthen your core while working other body parts as well. It is a compound exercise in that it works the calves, quadriceps, glutes, back, chest, triceps, abdominals and shoulders. You will need high levels of core strength to do this exercise the right way.
It is a versatile exercise in that you can do it on level ground, on an incline, as a warmup or as a bodyweight cardio workout.
Do the mountain climber cross-body this way:
a. Start by getting in the push up position with your arms fully extended. Keep your hips and torso in a straight line. Don't let your hips sag and don't point your butt in the air during this exercise.
b. Do the exercise by moving your left knee straight up and across your body to the right armpit area (keep your abs braced). Also, don't let your foot touch the ground as you do the movement.
Move your left leg back to the starting position and repeat with your right leg. Alternate your leg movements until you have completed all repetitions.
Here is a great free download of a fat-burning bodyweight workout book, if you need some guidance.