How much cardio exercise do I need to improve my fitness level?

The cardio guidelines for improved fitness levels include performing your chosen cardio activity for 20-60 mins at an intensity of 60-90% maximal heart rate (220-age), 3-5 days a week. Build a solid cardio foundation first by training at an intensity of 60-75% maximal heart rate for 30-60 minutes. Then work toward increasing the intensity of your workouts by adding interval training into your cardio program.
To become more cardiovascularly trained, the American College of Sports Medicine (ACSM) recommends a combination of moderate and vigorous physical activity for approximately 150 minutes a week. (If the majority of the activity is vigorous, 75 minutes a week is sufficient).
Robert S. Kaufmann, MD
Internal Medicine
It doesn't matter how much but no matter what your fitness level is it will improve. You start at your baseline and any cardio exercise will improve your fitness level.  You can guage your success by the amount of speed and distance increase.  Also your ability to last longer without stopping.

I recommend three or four times a week for 30 or 40 minutes depending on the intensity of the work out and your current fitness level.  You will be able to gauge your improvements by monitoring your time, speed, distance, and intensity levels.

Dr. Michael Roizen, MD
Internal Medicine
Any cardio exercise will improve your fitness level if you are as out of shape as most of us are, but you need to keep doing a little more cardio exercise three times a week at a little more intense level to keep improving your fitness level.

Since we are all different here what YOUR better fitness level is can be an interpretable factor when answering this question. How much cardio you do should be based on what your health and fitness goals are and what you are physically capable of doing.

If you are trying to make a healthy lifestyle change then consider 30 minutes of moderate cardio (walking, hiking, biking) 5-7 days per week. If you are more athletic then consider training at 60%-90% of your maximum heart rate. Simply take the number 220, subtract your age, and multiply that number by .60 and .90 to get a basic calculation of your training heart rate zones.  If you are trying to lose weight, then the National Academy of Sports Medicine recommends, cardio 3-5 days per week, 20-60 minutes at a time, at 60%-90% of your maximum heart rate though, given our busy lives, it may be more realistic to go with 5-7 days with 30 minutes of cardio at a given time.

Remember to consult your doctor before starting any program to ensure your body can handle the stress of cardio workouts.

Wendy Batts
It is important to consider the goal behind doing cardio. If your goal is achieve and maintain general health, participate in general activities for an accumulated 30 minutes per day at a moderate intensity 5-7 days per week. Moderate intensity here being defined as any activity that increases your heart and breathing rates.
If your goal is to increase your cardiorespiratory fitness, that is, increase the work capacity, efficiency and performance of your heart and lungs; then work at 60-90% (moderate to high) intensity for 20-60 minutes per day 3-5 days per week.
Remember, if you are new to cardio, the point is to simply just move more every day! Don’t get too caught up in the details just yet and don’t do too much too soon. And the more you enjoy the activity, the more you’ll do it so be sure to look for cardio that you enjoy.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.