What’s the best cardio workout? Is it different for each individual? As engineers, we decided to dig into the data.

This article summarizes an experiment we conducted with a variety of cardio workouts. We tested popular YouTube workouts, standard gym equipment, and professionally designed routines.

It was interesting to learn that the best cardio workout was nearly twice as effective for weight loss than the worst. In my case, if I did the worst workout instead of the best for a year, I would leave 24 pounds of weight loss on the table.

The goal of this article is to summarize our results and help you find the most effective form of exercise. Let’s begin!

what is the best cardio workout ryan and alex duo life

what is the best cardio workout?

Alex and I have always been fans of working out together. There are many incredible benefits to working out with your partner.

When we started sweating it out together, it quickly became clear that our bodies responded very differently to different forms of exercise. It was eye-opening to see Alex’s heart rate peaking during a run when I needed to do a high-intensity workout to see the same result.

Since we’re engineers, we wanted to collect the data to make sure we were maximizing our results in the least amount of time. This article is a summary of our results and takeaways.

Keep in mind that the results are our own. Yours would be different. Therefore, we share all of the experimental details so that you can replicate it and determine which form of cardio is best for your body.

The Best Cardio Experiment details

In this section, we will outline (in great detail) the specifics of our experiment.

We discuss the goal of the experiment, our hypothesis, the workouts we did, and the variables that we controlled to get accurate results.

Cardio Experiment Goal

I have always been a fan of high-intensity cardio workouts. I started running at a young age, ran cross-country competitively, and played soccer year-round throughout high school.

Alex has also been a lifelong fan of cardio workouts, but she refers to herself as a “one-speed pony.” She has never liked the high-intensity workouts as much as I do and prefers long-distance running, swimming, and lifting weights.

Workout preferences aside, the purpose of this experiment was to identify the best, most effective cardio workout. Since we’ll be using heart rate analysis, our definition of “the best, most effective workout” is the workout that burns the most calories.

We will measure calories burned during the 20-minute workouts and for 60 minutes immediately after for the “afterburn effect.” We understand that there is more to a workout than just calories burned, but for experimental purposes, this was our best metric.

Our Hypothesis

Based on our experience, what do we think will be the best cardio workout? Probably the workout that has the fastest pace, fewest breaks, and engages the most muscle groups, because that will burn the most calories.

“I believe HIIT cardio workouts are going to be the best. Workouts like Insanity are full-body explosive cardio designed with only enough breaks to prevent you from fainting.” -Ryan

“Although I love running and enjoy spin classes, I don’t think either will be the best cardio workout. They don’t engage enough muscle groups. I expect some form of HIIT to win.” –Alex

We have experience doing a variety of HIIT workouts and even designed an at-home, total-body HIIT routine for couples.

About The Experiment

This was a highly detailed experiment to determine the best cardio workout. We did our best to control all variables from diet to sleep quantity to hydration to alcohol consumption.

We’re all unique individuals, and our results could be different than yours. In this post, you have everything you need to repeat the experiment and find out what is the best cardio workout for you.

If you plan to repeat the experiment, or if you’re just a geek like us, below are the variables we tried to control for. If you’re not, skip down to the results section.


1. Workouts (20 minutes of each):

Note – If there was a warm-up included in the routine, that was skipped. Instead, we followed a consistent warm-up for all workouts summarized in the “Controls” section below.

2. Participants:

  • Ryan: 30 years old, 175 lbs, 7% Body Fat Composition (collected using this caliper), and intermediate/advanced fitness ability according to our fitness test
  • Alex: 30 years old, 105 lbs, 18% Body Fat Composition, and intermediate/advanced fitness ability

3. Days: One workout a day in randomized order (see Appendix V).


No health or fitness experiment is perfect. However, we did our best to limit lifestyle and diet variables with the following controls.

  • No alcohol during or two days before the start
  • 8-9 hours of sleep tracked using the Pillow app (sleep data in Appendix III)
  • Followed a portion-control diet plan before and during (food details in Appendix IV)
  • Morning workouts between 8:30 and 9:30 AM
  • No food or supplements before the workout
  • Ryan and Alex drank 40 and 20 ounces of water respectively before the workout
  • Collect data with Polar H7 HR Monitor during the 20-minute workout (referred to as “the burn”) and immediately after the workout for 60 minutes while reading by the pool (referred to as “the afterburn”)
  • No other workouts during the experiment
  • No music during workouts

We followed the below warm-up routine for 2.5 minutes (not included in HR data):

  • Run in place (30 seconds)
  • Jumping jacks (30 seconds)
  • Side step twists (30 seconds)
  • Stretch (60 seconds)

The results are in and they are conclusive.

The Best Cardio Workout Results

Based on our analysis, our experimental results are accurate and the data is conclusive. We didn’t graph heart rate data, however, there was a strong correlation between average heart rate and calorie burn during the workouts.

While calorie burn doesn’t need to be the end-goal for finding the “best” program, it was a good metric and rule-of-thumb for weight loss and for being pushed beyond our comfort zone. Other considerations for a great workout would be how accessible it is, how much you enjoy it, and cardiovascular and strength benefits.

Total Calories Burned Results

As shown in the graph below, Ryan burns a lot of calories during a 20-minute cardio workout. His maximum heart rate during BODi 1 and BODi 2 were 189 and 182 respectively. All other workouts were in the 140s and 150s.

Clearly, these workouts, which combined explosive total body strength exercises with HIIT, were effective, especially during the afterburn recovery period. The bike was Ryan’s least effective cardio workout.

Best Cardio Workout Experiment Ryan's Results

Next, we have Alex’s cardio workout data. BODi 2 was the clear winner for both Ryan and Alex. While this workout was miserably difficult (thanks Shaun T), it was reassurring to see that our bodies continued to burn calories rapidly while resting by the pool.

The rest of our results are similar except that Alex’s treadmill calorie burn was far more impressive than Ryan’s. This is great data for her to have, because she love’s running more than HIIT.

Best Cardio Workout Experiment Alex's Results for Total Calorie Burn

Total Weight Loss Potential Results

First, we understand that burning 3,500 calories does not mean you’ll lose a pound. If only weight loss and the human body were that simple. But, mathematically speaking, the following graph shows the efficacy of each cardio workout in terms of weight loss potential.

For example, if Ryan did 20 minutes of BODi 2 five days a week for a year, he would lose 49 pounds. If instead he did the Bike workout he would lose 25 pounds.

For Alex, it’s a similar story. She can sweat it out with Shaun T and lose 16 pounds, run on a treadmill and lose 14 pounds, or follow YouTube 1 and only lose 9 pounds.

Best Cardio Workout Experiment and Potential Weight Loss

Effective Cardio Vs. Less Effective Cardio

Of course, there are tons of immeasurable benefits to cardio, so we don’t want to say any one form is bad. However, if your goal is weight loss, there are less effective forms of cardio.

For example, let’s say Ryan loves the bike and commits to a year of riding instead of HIIT. After all, enjoyability should factor into the decision. However, he would need to exercise for an additional 78 hours that year to burn off enough calories to lose 23 pounds.

Ryan has a decision to make: Suffer through HIIT workouts or spend and additional 3.25 days on the bike!

You should run your own experiment because this data is invaluable. Let us know what you learn in the comments. Also, let us know if there is a form of cardio that you wished we tested. We’ll take these into consideration for our next experiment. We’d love to collect some data on swimming!

Ryan’s Most Effective Cardio

BODi 2 (Insanity Max :30 Cardio Challenge) was…

  • 11% more effective than BODi 1 (Transform :20)
  • 44% more effective than the treadmill
  • 91% more effective than the bike
  • 68% more effective than YouTube 2 (POPSUGAR Fitness)
  • 77% more effective than YouTube 1 (Fitness Blender)
Alex’s Most Effective Cardio

BODi 2 (Insanity Max :30 Cardio Challenge) was…

  • 7% better than BODi 1 (Transform :20)
  • 13% better than the treadmill
  • 30% better than the bike
  • 60% better than YouTube 2 (POPSUGAR Fitness)
  • 73% better than YouTube 1 (Fitness Blender)

Again, we encourage you to find the best cardio workout for you. We’re glad we did.

The Best Cardio Workout Conclusions

In our experience, professionally designed programs are always the best. Based on our transformation photos and body measurements, the best programs we have found are on BODi. However, if you have a favorite workout platform or trainer, please share in the comments so we can sweat it out.

Here are our key conclusions from our cardio experiment.

1. Not All Cardio is Created Equal

Figure out which cardio is best for you. You can do this by tracking your workouts with a heart rate monitor or wearable.

For Ryan, no other form of cardio came close to HIIT, but for Alex, running on the treadmill (8.5-minute mile) was a close runner-up.

The exercise bike and YouTube workouts were poor cardio workouts for both of us (according to the heart rate analysis charts in Appendix II).

The less effective cardio workouts are slower-paced with too many breaks to maintain an elevated heart rate. You’ll know they are bad because they aren’t challenging enough.

The good news that when they are challenging, they continue to work for you even after the workout is over.

Update: Since doing this experiment, Ryan trained for and crushed his first two marathons (thanks to his coach, Alex). For him, running outside at a faster pace (7-minute mile) yielded much higher heart rate and calorie burn data. The 8.5-minute mile pace in this experiment wasn’t challenging enough.

Running changes your body in ways other forms of exercise don’t. We highly recommend running outside, and while you’re at it, why not a marathon?

2. Partner up

Let’s face it. Cardio isn’t that fun.

But it can be when you do it as a couple. You gain accountability, push yourselves harder, and boost your attraction to each other. Just to name a few of the benefits of working out as a couple.

Don’t believe us? Recruit your partner and give our couples workout routine a shot.

3. Count calories and measure metabolim

If you’re not eating the right amount of calories, no form of cardio will be effective for you. Most people we work with are not eating enough of them.

In this experiment, it was important for us to learn that Ryan burns 3X calories compared to Alex while requiring 2X calories from meals.

We know that everybody and every body is different, but this was a significant finding.

After this experiment, we started paying more attention to portioning our meals and occasionally tracking our calories to make sure we were fueling enough. This is important because you won’t see results from your cardio if you’re not eating the right amount of fuel.

We share our learnings in our article titled ‘How to Manage Diets as a Couple.‘ If you haven’t tracked your calories before, follow the guide in our 30-Day Weight Loss Challenge.

Lastly, if your metabolism is off, your cardio efforts will be fruitless. Fortunately, you can track your metabolism in real-time now. We did and the results of our 3-month metabolism experiment are impressive.

Closing Thoughts on The Best Cardio Workouts

So, what’s the best cardio workout?

Based on this data, total body HIIT. It should be fast-paced, incorporate bodyweight strength training, and keep you in zones 3, 4, and 5 for nearly the entire workout. It should be really hard, but you only have to do it for 20-30 minutes.

If you want effective cardio, there are a variety of great programs on BODi. Below is our review of the BODi membership and if you sign up, these are the best (most effective) Beachbody workout programs.

If you have any questions about our experiment, ask away in the comments below. Just make sure you review Appendix 1 through 6 below for experiment specifics.

For more helpful fitness resources, such as our 30-Day Ab Challenge, our guide on how to build a home gym, or the free 8-Week Resistance Band Workout Routine, head over to our Work Out At Home Page.

Appendix i

In this section, we share our workout summary, day by day. Additionally, we’ll share links to the exact workouts we followed so you can repeat the experiment.

Day 1 – Treadmill

So, what is the best cardio workout?

Today, we started the experiment on the treadmill and ran an 8.5-minute mile pace for 20 minutes. For me (Ryan), it was difficult since I rarely run. Therefore, I was breathing heavy and sweating considerably at the end of the workout.

Surprisingly, the workout did not produce a very high average heart rate, 146 bpm. My lifting and cardio workouts regularly have me in the 150-170 bpm range.

Alex is a great runner, so this was easy for her but also produced a high average heart rate. She even burned more calories in the afterburn than she did in the burn. It was interesting to see how our bodies reacted differently to these workouts.

Running on the treadmill was boring for both of us. We much prefer to run outside. For me, it didn’t help that I was stuck watching a comedy cooking show in Japanese.

Day 2 – YouTube Cardio 1, Fitness Blender

YouTube Cardio 1, Fitness Blender

Today’s workout was a letdown for both Alex and me. It was a HIIT workout, which is my favorite form of cardio, but the exercises were too short and separated by too many breaks. Therefore, our average heart rate was very low. For me, 130 bpm, and for Alex, 115 bpm. This is much lower than yesterday’s treadmill workout.

This might be a great workout for the beginner, but for us, they were far too easy. It’s definitely not going to be the best cardio workout.

Alex also found the video to be misleading as it promised 188-375 calories burned (shown right on the screen). She topped off at 67 calories burned instead.

Day 3 – BOD Cardio 2, Insanity Max :30, Cardio Challenge

BOD Cardio 2, Insanity Max :30, Cardio Challenge

Day 3 was insane, hence the name Insanity. The Insanity Max:30 Cardio Challenge delivered a high average heart rate and calorie burn for both Alex and me.

It was a major challenge, and during the afterburn, I could tell my body was fighting to recover. I was amazed that I burned 653 calories from a 20-minute workout (including the 60-minute afterburn). Very impressive results for Alex, too, burning a total of 216 calories!

The workout consisted of 45-second moves and three short breaks. I credit these great numbers to the intensity, variety of muscle groups recruited, and the explosive total-body moves.

Day 4 – YouTube Cardio 2, POPSUGAR Fitness

YouTube Cardio 2, POPSUGAR Fitness

Today’s cardio workout was another free YouTube workout letdown, as you can see from Alex’s post in our Duo Life Community. It was just…


For us, slow also means boring, and that is never a good thing when it comes to workouts. They are hard enough to be consistent with when they are exciting, challenging, and bringing results.

This is another beginner’s workout, in our opinion. Maybe selecting free workouts based on the number of YouTube views was not the best choice.

I burned 68% fewer calories, and Alex burned 60% fewer calories than yesterday’s BOD Cardio 2, Insanity Max:30, workout. Wow, that would add up to a ton of calories after a few months of working out!

Day 5 – BOD Cardio 1, Transform :20 Sample Workout

BOD Cardio 1, Transform :20 Sample Workout

Today’s cardio workout was a burner! This was the first time doing this workout for both Alex and me. And, it took some focus to do the moves properly. Both of us hit our highest heart rate maximum yet! For me, 189 bpm, and for Alex, 170 bpm.

This routine requires a step, and that definitely increases the difficulty level and challenges the muscles in each leg (glutes especially) individually. Core exercises are a major component too. Since we were seated on the step doing core moves quite frequently, I was surprised that we maintained such a high average heart rate.

This cardio workout challenged not only our heart and lungs but also our upper, lower, and core muscles. We both hit muscle failure in the 20 minutes so that is very impressive.

Day 6 – Exercise Bike

Today we followed the exercise bike program outlined in Appendix VI. As I reported to our Duo Life Community, this workout took me by surprise. I sweated like crazy, probably because my leg muscles were firing on the many steep hills built into the program.

Unfortunately, my heart rate dropped off quickly after the workout finished, and it ended up being the worst cardio workout for me. This surprised me as I thought it was far harder than the free YouTube workouts. However, this shows that muscle engagement during cardio workouts is critical. The exercise bike is not the best cardio workout.

Alex thought the exercise bike was pretty easy, which is interesting because, according to the heart rate analysis, it was a better cardio workout for her than the YouTube cardio workout. This just goes to show that everyone is unique! And it never hurts to have a heart rate monitor!

appendix iI

Below are the experimental data that contains calorie and heart rate data for Ryan and Alex.

Best Cardio Workout Data Ryan Calories and Heart Rate
Best Cardio Workout Data Alex Calories and Heart Rate

Appendix iiI

Click below to see all heart rate analysis graphs from our Polar H7 heart rate monitors using the Polar Beat app. Heart rate analysis for Ryan and Alex is shown for the burn and afterburn.

View All Heart Rate Analysis Graphs

what's the best cardio workout heart rate analysis youtube cardio 1 burn
what's the best cardio workout heart rate analysis youtube cardio 1 afterburn
what's the best cardio workout heart rate analysis youtube cardio 2 burn

what's the best cardio workout heart rate analysis youtube cardio 2 afterburn
what's the best cardio workout heart rate analysis exercise bike burn
what's the best cardio workout heart rate analysis exercise bike afterburn
what's the best cardio workout heart rate analysis treadmill burn
what's the best cardio workout heart rate analysis treadmill afterburn
what's the best cardio workout heart rate analysis bod cardio 1 burn
what's the best cardio workout heart rate analysis bod cardio 1 afterburn
what's the best cardio workout heart rate analysis bod cardio 2 burn
what's the best cardio workout heart rate analysis bod cardio 2 afterburn

Appendix IV

Pillow App Sleep Data:

appendix V

Portion Control Container Tracking:

  • Ryan: 7 green, 3 purple, 5 red, 4 yellow, 1 blue, 1 orange, and 6 tsp allowance
  • Alex: 3 green, 2 purple, 4 red, 2 yellow, 1 blue, 1 orange, and 3 tsp allowance

Typical foods:

We eat a mostly vegetarian diet (fully for Alex) of organic whole foods. We also stick to a 16/8 intermittent fasting plan.

For more details on healthy eating, see our Eat Clean Page.

Appendix vI

Randomization of workout order:

Appendix viI

Program settings for the exercise bike (LifeFitness brand):

  • Select the Classic Cardio program (a random mixture of gradual and steep hills)
  • Ryan: Difficulty level 13 of 25 for 20 minutes
  • Alex: Difficulty level 9 of 25 for 20 minutes
  • Maintained 70-100 rpms
  • Never fell below 70 rpms (about 15 mph) on steep hills, and usually never fell below 75 rpms

Pictured below.

Bodyweight Workout Plan Form V2 Ryan and Alex Duo Life

8-Week Bodyweight Workout Plan

Download and instantly access the 8-week bodyweight exercise program including the following.

  • Videos of the 70 best upper body, lower body, core, and total-body cardio exercises with professional instruction to ensure proper form.
  • An 8-week workout calendar and rep tracker sheet with built-in variety and periodization.
  • A program guide built for your current fitness level: beginner, intermediate, or advanced.
  • Access to all future revisions to the program.

Plus, we're always here for support.

Or, download and get started for free.
As Seen In Feature Bar Ryan and Alex Duo Life

Hey we're Ryan and Alex

The creators of Ryan and Alex Duo Life. We are a husband-wife duo and “lifestyle engineers.”

After eight years working in the corporate world as engineers, we left our high-powered jobs to tackle our true passion — helping couples engineer their best lives.

The synergy of our engineering minds and ten years of health coaching experience produced Ryan and Alex Duo Life. Our mission is to help you transform your bodies, minds, and relationship as a couple.

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