This form of exercise has become popular
for a number
of reasons. The equipment (bike) is already provided, the
workout is low impact, it is performed indoors. Most importantly, the seat should be placed in the correct position to avoid injury and to maximize the effectiveness of the workout. Cycling (even stationary) can be a great way to burn calories.
Rowing Machine, It's almost a complete body workout. Done correctly, this can be a challenging exercise.