Is it better to do my cardio at a high intensity or low intensity?

The answer to this question is dependent on the individual - task - goal. Is the goal for wellness, weight management, or sports conditioning? Within that goal there is a need to identify specific tasks at hand. For example, if the goal is sports the demand for golf and soccer is quite different. The same holds true if you are trying to lose twenty pounds or reduce stress to enhance your wellness. Once the goal and task has been identified the most important aspect becomes the individual. High intensity cardio might not be the best place to start for an individual based on their medical history and current thresholds. Litmus tests such as Astrand Treadmill Test are a great start to identify current abilities and thresholds. 

It is important to remember low, medium, or high intensity workouts are all good choices. Each has benefits and limitations; a combination of all three is desirable long term. Deciphering which one is for you is the most important factor to implementing a successful program. 

Wendy Batts
Usually this question is posed within the context of the goal of weight loss, so we’ll talk about it that way. Often this question boils down to “what intensity of cardio is better for losing weight?” The short answer is that the best type of cardio, whether low or high, is the one you will do consistently over time.
Now, with that being said, if we were to compare only intensity, the optimal goal is to start at a lower intensity if you are new to cardio and slowly work your way to higher intensities as your endurance and cardio respiratory work capacity improves. This is because you will just flat-out burn more calories during the workout at higher intensity. And remember losing fat is about burning more calories than we consume over time. The other advantage to higher intensity cardio is that the “after-burn”, or the calories we expend afterwards to adjust to the workout, is actually higher. So not only are you burning calories during your cardio, but after your cardio workout as well. Both of which will contribute to hitting your weight loss goals faster. Remember to progress slowly with baby steps though because doing too much too soon can lead to injury or eventual burn out.

I find it is most effective to incorporate both high and low intensity cardio into a well-rounded fitness routine. High intensity cardio is a great calorie burner and an optimum choice for weight loss. Low intensity cardio will build your base level of fitness and I like to incorporate it into your “recovery” training days. The best way to track your intensity is with a heart rate monitor. It is also important to note that if you are new to exercise or if you have limitations placed on you by your doctor, you may need to continue participating in low intensity activities until your doctor clears you for higher intensity cardio.

Dr. Mike Clark, DPT
Regardless of your health and fitness goal(s), both high and low-intensity cardio have their place in a well-designed program. High-intensity cardio can help you burn more calories for weight loss goals and allow you to achieve higher levels of conditioning necessary for participating in sports and athletic activities; however, lower to moderate intensity cardio is great for building a base level of conditioning, which teaches your body how to burn fat more efficiently, and for where your program calls for a recovery day, allowing your body to rebuild and repair itself from the higher intensity exercise sessions you perform.
Dr. Michael Roizen, MD
Internal Medicine
It depends on what your doctor okays and how active you have been recently.  If your doctor gives you the A-OK, getting your heart rate up and keeping that intensity high will burn more calories (and melt pounds), but low intensity is still good for your cardiovascular health, mood, and waistline.  Any exercise and persistence (high intensity can promote injury) are keys. Start slow and work up gradually (to avoid injury) to a higher intensity if you can or at the very least (if your doctor says it’s okay), try to go as fast as you can for at least a minute during your work out.
If you are just starting an exercise program, I feel one of the first items to buy would be a good heart rate monitor watch (around $75). For a beginner, it is best to keep your heart rate at approximately 65 to 75% ( or less) of your predicted heart rate maximum.  This is very simply calculated by subtracting your age from 220. So if you are 45 years old, 220 minus 45 = 175.   So now you take 65% of 175, which is 114. (175 times .065 = 114).  Likewise, 75% of 175 is 131.  So keep your heart rate in this range, from 114 to 131.  Start slow, and gradually work up to at least 30 minutes in this range.  Once you can comfortably work out in this range for 30 minutes at least 3 times a week, you are ready to progress to the 2nd of three levels or zones. For now, just stay in this zone, which is commonly referred to as Zone One, or the Recovery Zone.

Well that will determine what your goals are.  Some athletes will need to stick to a certain type of cardiovascular routine.  However, there is nothing wrong with doing both.  Each low and high intensity workouts have their own benefits and it helps you not get bored in your rountine as well.  Just remember if your goal is weight loss it is all about how many calories you burn not where your heart rate is at.
Your goal, available time, and current level of conditioning will determine which intensity is best. Are you doing cardio for health, performance, or weight loss? Performance cardio training will dictate a style of training that mimics your sport's demands. If your sport requires continuous bursts of high intensity work with short rest or low intensity breaks, then the use of intervals may make sense. Interval training cycles training intensity between high and lower throughout the workout. If your goal is weight loss, either style of training will burn calories. Your available time may ultimately be the factor that determines which is best. Performing cardio, if your conditioning allows, at a higher intensity will allow you to burn more calories and fat per unit of time. If you cannot handle the demand of higher intensity work, you can still get the calories burned, it may simply take up to twice as long.

Continue Learning about Cardiovascular Training

Does Slow Exercise Burn More Fat?
Does Slow Exercise Burn More Fat?
You'll find it on virtually every cardio machine at the gym: instructions on how to hit your fat-burning zone. Essentially, it means you get to work o...
Read More
Why am I losing muscle even though I'm doing cardio training?
Int'l Health, Racquet & Sportsclub Association (IHRSA)Int'l Health, Racquet & Sportsclub Association (IHRSA)
You’ve probably heard some people say that they were losing muscle and got flabby while they were do...
More Answers
Is there a good diet to increase cardiovascular endurance performance?
Manuel B. Torres Jr., MDManuel B. Torres Jr., MD
If you’re an active athlete, carbs are the way to go. What I find is that most patients have a tende...
More Answers
What Are the Benefits of Running?
What Are the Benefits of Running?

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.