You’ve probably got your strength training down, but what about your cardio? There are so many kinds out there these days, but which is right for you and when should you do it? Oxygen made it simple: We narrowed your choices down to the four most popular modern protocols, giving you the skinny on their benefits, their execution and their applicability to your lifestyle and your goals. Read on to make them part of your programming and reach your goals faster.

Finding Your Maximum & Target Heart Rate (MHR/THR)

You may know of the old max heart rate calculation of 220 minus your age, but that formula is outdated. It was based on a 1970’s study that barely included women, so researchers at the Mayo Clinic have modified the formula thusly:

200 – (your age X .67) = MHR

To find your target heart rate, multiply the percentage of effort by your MHR. For example, a 30-year-old woman working at 70 percent would look like this:

200 – (30 X .67) = 180 MHR

180 X .70 = 126 THR

Steady State

Though it is definitely the most inglorious of all the modalities, steady state cardio still deserves a spot in your weekly training schedule. With this type, you work up to a target heart rate and keep it there for a set duration of time, anywhere from 20 to 60 minutes, depending on your goals.

This might sound tedious, especially if you’ve only got limited time to train. But bolstering your aerobic system can power everything from endurance to digestion to sleeping, and will improve resting heart rate, reduce stress and even increase the capacity of your heart to pump blood. Plus, if your aerobic system is on point, you will recover faster from other cardio modalities and intense strength training.

Do steady state cardio after your strength training or on a separate day all its own up to five days a week.

Duration: 20 to 60 minutes
+ 
Energy Systems Worked: Aerobic
+
Intensity level: Low to moderate (60 to 70 percent your MHR)

HIIT: High-Intensity Interval Training

If you don’t know about HIIT, you’ve undoubtedly been living off the grid in a yurt. HIIT involves alternating bursts of all-out intensity (90 to 100 percent) with periods of reduced intensity (50 to 60 percent) for a set duration of time, with a work to rest ratio of 1:2 to 1:3. This essentially means that you train both your aerobic and anaerobic systems simultaneously and hone your metabolic flexibility — i.e., your ability to transition between burning fat (during the recovery) and burning carbs (during the intervals).

But there’s a chance that you — and everyone else — are doing HIIT incorrectly. “True HIIT has a goal: to be bigger, faster, stronger, and the like,” says Fabio Comana, CSCS, faculty instructor for NASM. “To do HIIT, you have to know what your maximal performance is — the most number of reps you can do, how fast you can run, how high you can jump. Then your intervals are done near that maximal intensity, or at a percentage of that intensity, to improve performance.”

In the fitness industry, however, most people do not allow enough time for their energy systems to recover. For example, if you’re working at maximal intensity for 60 seconds, you’ll need about two to three minutes to fully recover (a 1:2 or 1:3 ratio of work to rest). Most people use a 1:1 ratio, which is not enough time to bounce back from all-out intensity. The result: a decrease in intensity with each interval, fewer calories burned and an increase in the chance for injury over time, according to Comana.

The take-away: Give yourself a max performance test before programming your workout. Run as fast as you can on the treadmill, do as many burpees as you can or perform as many pushups as you can for 30 seconds or the desired work bout interval. Then program a HIIT workout with a 1:2 to 1:3 work-to-rest ratio to reap the most benefits.

HIIT can be used by any athlete at any period during her training year, though it should be spaced out evenly throughout the workout week because of its intensity and shouldn’t exceed more than three sessions per week.

Duration: 15 to 30 minutes 

+ 

Energy Systems Worked: aerobic & anaerobic 

+ 
Intensity level: moderate to intense (50 to 100 percent) 

Research Roundup

Tons of research has been done on HIIT, including a recent study in the Journal of Obesity that found that 12 weeks of regular HIIT training drastically reduced body fat and increased lean mass and aerobic power. A paper published in Cell Metabolism discovered that when you exercise intensely, your body responds by flipping a genetic switch that increases the production of fat-burning enzymes, essentially altering your DNA for the better!

Tabata

Tabata training is a kind of HIIT, but one that takes less than five minutes. The idea is to work as hard as you can for 20 seconds, rest and recover for 10 seconds and repeat that sequence for a total of eight rounds, or four minutes. Sounds crazy, yet one six-week study found that participants increased their anaerobic capacity by 28 percent, and their VO2 max and aerobic power by 15 percent! Because you’re forcing your body to work at full capacity without full recovery, it responds by increasing its oxygen uptake, increasing both aerobic and anaerobic capacity, and improving VO2 max as a result. Tabatas also incinerate more calories than a regular 60-minute aerobic workout, both during the workout and in the 12 to 24 hours following because of their intensity. Tabata is a great training protocol for sports enthusiasts as well as regular gym-goers looking for a new way to burn body fat and improve their energy systems. When possible, do them before strength training to be able to dedicate 100 percent of your energy to them, and leave a day or two between Tabata workouts to allow for full recovery.

Duration: 8 minutes 

+ 

Energy Systems Worked: anaerobic
+

Intensity level: super-intense (100 percent)

VIIT: Variable-Intensity Interval Training

It might seem like nitpicking, but there is a difference between VIIT and true HIIT training. Remember that with HIIT, your work to rest intervals are 1:2 to 1:3; with VIIT, both your work-to-rest ratio and intervals can vary in time and intensity to keep your body guessing. “VIIT gives you the best of both worlds because you are able to do more intervals in a set amount of time, get more EPOC effect as a result and reduce your risk of injury,” Comana says. This means both your aerobic and anaerobic systems are taxed, you work both your fast- and slow-twitch muscle fibers and you’re less prone to become injured, according to Comana. As a bonus, the EPOC (exercise post-oxygen consumption) boost means you’ll burn an additional 20 to 35 percent more calories during the session and the 24 hours following.

Like HIIT, you still need to know where you fall in terms of max performance, so give yourself a 30-second test to determine what that max might be. Then plan your workout to alternate maximal intensity intervals with submaximal ones so your body has a chance to fully recover.

Try VIIT if you’re trying to shed body fat quickly or to keep things fresh. It is not recommended for women who are dieting for a show, however, as it is pretty intense.

Duration: 20-30 minutes
+
Energy Systems Worked: aerobic & anaerobic
+
Intensity level: 60 to 100 percent 

Four Fast Answers to Common Cardio Questions

1. Should I do cardio on an empty stomach?

The jury is out on this one. Some people believe that it taps into fat stores better, while others insist that you’ll “bonk” due to depletion and end up burning muscle instead of fat. If you want to literally run on empty, stick to steady-state work that won’t leave you completely fried post-session. If you’re doing a more intense form of cardio, however, have a meal that contains carbohydrates at least an hour beforehand so you can power through it without failing.

2. Should I do cardio before or after weight training?

If muscle hypertrophy — i.e., growth — is your main focus, lift first to avoid burning up all your glycogen stores. If your goal is a metabolic boost, do your cardio first.

3. Does yoga count as cardio?

Not really. Yoga does have a lot of respiratory benefits because of the deep breathing and relaxation involved, but it does not burn an appreciable number of calories like a cardio workout would.

4. On my active rest days, can I do cardio?

Yes, but it should be very low-intensity, such as taking a walk or a very easy hike, or playing with your kids at the beach. Active rest days are for recovery and repair, and any activity you do should not be strenuous enough to detract from that purpose.

Written by Lara McGlashan & Michelle Basta Speers for Oxygen Magazine and legally licensed through the Matcha publisher network. Please direct all licensing questions to legal@getmatcha.com.