Fitness Basics: Cardio

Julia Malacoff
by Julia Malacoff
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Sweating it out on the treadmill, elliptical or rower is what many people imagine when they think of “working out.” While cardiovascular exercise is just one component of a complete fitness plan, it’s important to understand how it can help you progress toward your goals and enhance your overall health.

Cardiovascular exercise is basically anything that raises your heart rate to at least 50% of your maximum heart rate. While there are generic formulas for finding your max heart rate (such as subtracting your age from 220), experts agree there’s enough variation from person to person that the best way to determine your heart rate zones is to use your own personal data via a heart rate monitor. (Another option is to use your rate of perceived exertion.)

Most often, we think of activities like running, cycling and swimming as cardio. But any number of other activities — including strength training — can qualify as cardio when your heart rate gets high enough. There are a few main reasons to ensure you’re boosting your heart rate regularly.



The American Heart Association’s cardiovascular exercise guidelines for overall health are at least 150 minutes per week of moderate-intensity aerobic activity, 75 minutes per week of vigorous aerobic activity, or a combination of both, preferably spread throughout the week.



When it comes to optimal health, cardio is arguably more important than strength training, says Sean Light, CEO of 4A Health and former L.A. Lakers strength coach. “In 2020, humans are living in hyperspeed. This means that aerobically, we are probably all lacking some efficiency. The aerobic system is absolutely the most important energy system for you to have developed.”



Cardio helps establish and maintain a baseline level of fitness, explains Steven Mack, a certified strength and conditioning specialist and owner of Simple Solutions Fitness. “If you only have time for strength training or cardio, you can get away without performing cardio, but you might find yourself gasping for air between supersets,” he adds. That’s because it’s possible to be “advanced” in strength training, but a “beginner” in cardio.

Even if time is an issue, you may want to consider adding some form of cardio to your routine. If you’re trying to get stronger, we know that, to some degree, the volume of strength training you do matters. “If you’re limited to an hour in the gym and you’re trying to get in more volume, you’re going to need to get into better shape to squeeze in more work,” Mack points out.

Not all cardiovascular exercise is the same. Here are the three main types, plus when to do them:



This is generally performed at a pace where you can maintain a conversation comfortably, Mack says. This can be done walking at an incline on the treadmill, jogging, circuit training, using an elliptical, cycling and so on, according to Light. Often, LISS workouts are on the longer side — anywhere from 30–90 minutes.

A major perk? “Because it’s so easy, you can generally perform plenty of LISS without causing too much damage or fatigue that will affect your strength training,” Mack adds. “Perform it as often as your goals allow, once or more per week.”

There are other benefits to low-intensity cardio, too. “When the doctor tells you to exercise more, this is what they want you to do,” Light explains. “It lowers blood pressure, stress, random aches and pains and a whole lot more. The greater efficiency that your aerobic system has, the more resilient you will be throughout your day, which simply leads to a happier life.”



This is performed at or slightly above the point where you can hold a conversation, Mack notes. You can do moderate-intensity cardio at a steady pace or interspersed with intervals of rest. When should you choose this one? “Moderate intensity burns more calories per unit of time than low-intensity steady state but, it is generally more fatiguing.” Most often, MIC is performed for anywhere from 20–60 minutes.



This is performed at a pace where it is difficult or impossible to carry a conversation, according to Mack. There’s general high-intensity training, where you remain at a steady pace, and high-intensity interval training (HIIT), where you intersperse bursts of exercise with periods of rest.

If you’re performing high-intensity cardio, how do you know when you’re going hard enough? “It generally takes all your focus to keep up this pace, and you will find yourself getting tired pretty quickly. Because it is so fatiguing, it is generally not performed in high volumes, immediately before strength training or too close before a major event.” Generally, high-intensity training is performed for 10–30 minutes.

Lastly, safety is key when it comes to high-intensity training. “This is the most marketable of the cardio types and easily the most butchered,” Light says. Make sure to consult with a qualified professional before performing high-intensity exercise, particularly if you’re new to fitness.

“The NSCA recommends that beginners start off with 20–40 minutes of cardio 2–3 times per week,” Mack says. “This amount of cardio is what I use as a baseline, depending on the goal.”

Light generally recommends a 30–90-minute cardio session twice per week as well as an ultra-high-intensity 60-second burst session once per week. “The long duration will improve your cardiac health by increasing the amount of blood your heart can pump,” he explains. “The high-intensity bursts will improve how much blood the heart can pump. This allows more blood to be circulated, thus improving your aerobic capacity and overall health. The more low-intensity, long-duration exercise you do, the healthier you will become.”

The one exception to these guidelines is if you’re trying to gain muscle. “The more cardio you do, the more it will compromise your ability to gain muscle, so I would just avoid it altogether until you reach your muscle-mass goals,” Light advises.

  • Invest in a chest strap heart rate monitor. “Wrist monitors are nice, but questionable in their accuracy,” Light says. “I highly recommend a chest strap. You will always know what zone you are in. Without it, it’s really hard to know which system you are training.”
  • Separate cardio from strength training. “Depending on the amount of cardio performed, some studies have found that there may be an ‘interference effect’ in the amount of muscle mass that you can gain while concurrently performing cardio and strength training,” Mack says. As was already mentioned, if your goal is muscle gain or maximum strength, that might mean you skip cardio altogether. For those pursuing fat loss, retaining muscle mass is still important, so it’s generally recommended you perform cardio on a different day from your strength training workouts or after your strength workout to minimize any potential interference.
  • Bonus: Measure resting your heart rate (RHR) and heart rate variability (HRV). You can keep track of both via several different types of fitness trackers. “If you want to get the most out of your cardio, monitor HRV,” Mack says. “Heart rate variability is your heart’s ability to perform work at different intensities and recover to a baseline.” If you measure your resting heart rate each morning, you’ll know that you’re getting into better shape as that number trends down. “If your resting heart rate begins to tick up, this is an indicator that you might be performing high volumes of training that are leading to overtraining.”

Get your heart pumping with fast-paced HIIT workouts. Go to “Workout Routines” in the app to explore HIIT workouts and more.

About the Author

Julia Malacoff
Julia Malacoff

Julia (@jmalacoff) is a seasoned writer and editor who focuses on fitness, nutrition, and health. She’s also a certified personal trainer and Precision Nutrition Level 1 coach. Based in Amsterdam, she bikes every day and travels around the world in search of tough sweat sessions and the best vegetarian fare.


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