I actually get questions like this all the time. Seems simple enough, right? To me this is a very broad question. What is the goal of the cardiovascular work? To lose weight, improve fitness, aid the metabolism?
In most cases it is to lose body fat. So, how much cardio should you do to lose body fat?
It all depends on the person. I could never just say, “30 minutes and you will lose weight”. If you have been performing 30 minutes for months now your body might be used to it and no weight will be lost.
One must also consider what type of cardio they are performing and how intense the work is. I can tell you that someone running on a treadmill will burn more calories than someone on a recumbent bike for the same amount of time.
Is performing 30 minutes of “cardio” at a lower intensity better than 20 minutes of sweating and panting?
What everyone should focus on is what I call my law of “relativity” regarding almost any fitness aspect. The best answer I could give to someone who asks, “how much cardio should I do?” is, “more than you were”.
My “relativity” rule means that as long as you do more (intensity, duration, frequency) you will burn more calories which aids in fat loss.
Don’t perform any cardio?
-Than anything will work.
Walking on the treadmill not yielding results?
-Start to jog.
My point is that changing the body is not a formula but the body cannot ignore more work. The body MUST react to the extra effort in one form or another.