Hail HIIT, the Cardio King

One of the lectures I was most excited about attending at Fit Fest was the HIIT vs. Continuous Cardio lecture. I’m a HUGE fan of HIIT and even more now- I don’t have time to stroll along on the elliptical while tweeting and reading Us Weekly (and don’t really miss it). Workouts for me are now shorter than ever, just as effective, and HIIT is the reason for that. I can get in a killer cardio session in 30 minutes or less, which is fantastic option when gym time is limited.

So I know HIIT is great, but how much greater?

What makes HIIT better than continuous cardio? Or is it even better than continuous cardio???

I have to say that first of all, the presenter for this lecture rocked.my.world. It was two hours long and when it was over, I wanted him to keep talking. His name is Dr. Len Kravitz and you can read more about him and his work here. He has devoted recent time thoroughly studying and experimenting with the differences between HIIT and continuous cardio, and here’s what he had to say (this is all paraphrased using the notes I took, but you can read the lecture notes online here and more about the publication here):

-The origins of HIIT training actually date back to 1912. The best Olympic runners, usually Scandinavian athletes, utilized HIIT workouts in their own training. The grandfathers of HIIT training are Saltin and Astrand- their first publication is from 1959 and all of the HIIT and interval techniques from then on were borrowed from their original research (including Tabata training, which I love so much). Saltin and Astrand introduced HIIT as a percent of VO2max and did 30 minute interval sets with 15 seconds on, 15 seconds off (“on” was at 100% VO2max).

-Interval training has continued to gain popularity since then, and in the 80’s Grete Waitz (who won the marathon 9 times) used different velocities for interval training: Fartleks (short bursts of energy), short intervals, long intervals, tempo and distance.

-One important thing to consider is the afterburn effect (EPOC = Post Exercise Oxygen Consumption) from any type of training. 2 hours after working out is when the highest afterburn occurs, but the largest chunk of that is 45 minutes after your workout. The higher the intensity, the higher the EPOC. During EPOC, the oxygen we consume is restoring physiological variables to pre-exercise levels.

-So as you can probably guess, HIIT increases EPOC. There’s also a 15% increase in capillaries, which may not seem like a lot, but when you have 49,000 miles of them, it’s significant!

-One other important thing to consider is mitochondrial density patterns with exercise, as they’re the fat-burning fireplaces of the body. With exercise, they’re 35% bigger and there are 15-50% more. It’s important to have balance with exercise though, because too much of a good thing can cause immune system breakdown.

Here are the BEST research-based HIIT programs:

*Graphics created with permission from Dr. Kravitz- they are his teachings, I just made the graphics as an easy way to find the info*








HIIT and continuous cardio are both fantastic ways to train, but through Zuhl and Dr. Kravitz’s research, it was determined that HIIT is indeed the cardio king. You can read more about their research here, and the above HIIT training methods.

Do you enjoy HIIT training? Who did yesterday’s HIIT challenge? 

Hope you all have a wonderful day and I’ll see ya later on the Family page with my 9-month PDB post.






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  1. Erica { EricaDHouse.com } on October 10, 2012 at 11:16 am

    FABULOUS post! Thank you so much for writing all this up. I’ve been meaning to incorporate more HIIT into my workout routine and this is just what I needed!

  2. avery on October 10, 2012 at 11:34 am

    I love interval training! I’ve found that my running times improve dramatically whenever I intergrate high intensity intervals. Then from a fatburning standpoint, it’s even better. I usually do it a couple times a week. I do notice some extra soreness from doing HIIT, so I try not to go too overboard so I can come to my next HIIT workout fresh and energized.

  3. Pam August on October 10, 2012 at 11:37 am

    What exactly does “rest” mean? I never know if i should be walking or jogging slowly!

    • Fitnessista on October 10, 2012 at 11:37 am

      it can be either active or passive rest

  4. Cat @ Breakfast to Bed on October 10, 2012 at 11:38 am

    I prefer hiit because it makes me feel like I may be either dying or doing less. My body can’t figure that part out, but it does seem to produce results.

  5. Anna on October 10, 2012 at 11:40 am

    Hi! Great post! When you say there is a 15% increase in capillaries what do you mean exactly? Do more grow over time as you do HIIT? Thanks!

    • Fitnessista on October 11, 2012 at 12:58 am

      exercise temporarily increases the density, so more blood can effectively be transported to organs

  6. Erin on October 10, 2012 at 11:41 am

    Awesome info, thanks for this Gina! As much as I love a good long run, some days I only have time for a quick and dirty treadmill session. Plus, I feel h-core when I crank up the speed!

  7. Michelle @ Eat Move Balance on October 10, 2012 at 11:49 am

    You’re inspiring me to be more conscious of bringing this back when I’m on the elliptical machine. I’ve slacked off, and just cruise on the machine reading a magazine to pass the time. I know I’ll get more bang for my buck if I bring in the HIIT. Thanks!

  8. Krystina on October 10, 2012 at 11:49 am

    I prefer HIIT because I’m lazy and hate spending too much time at the gym. 😛 20-30 minutes of HIIT a couple times a week is all I can handle in terms of cardio.

  9. megan on October 10, 2012 at 11:51 am

    gina – this is an excellent post! i have an MS in exercise physiology and generally cringe when reading blogs dispensing exercise advice with little to no research behind it. i love that you used legitimate sources and research while presenting it in an easy to understand (but very informative!) way. you had a great oppurtunity to attend that session with Dr. Kravitz!

    • Fitnessista on October 11, 2012 at 12:56 am

      thank you!! i’m so happy to hear you enjoyed it, and dr kravitz is a genius.
      i’m the same way- i get a little ragey to see workouts on sites that weren’t created by fitness professionals

  10. Kerry @ Totes My Oats on October 10, 2012 at 11:56 am

    I love HIIT… it definitely helps with distance running. I feel stronger on long runs when I throw HIIT into my workouts!

  11. Stephanie on October 10, 2012 at 11:59 am

    Wow, that was very informative! I most often gain my knowledge from fitness magazines or sites, but I really appreciate learning about the scientific research the supports our day-to-day training methods. I’m going to pin this for future research – this is great!

    • Fitnessista on October 11, 2012 at 12:55 am

      i’m so glad you found it helpful!

  12. lisa on October 10, 2012 at 12:00 pm

    I did 15 minutes last night on treadmill alternating 30 sec at 6.0 and 30 at 8.0. It was killer! I am going to incorporate 2 HIIT workouts/week, short and sweet!

  13. Ali @ Peaches and Football on October 10, 2012 at 12:02 pm

    I like HIIT for variety but boy those workouts wipe me out. Sometimes I just enjoy exercising at a more reduced level for longer. I can’t go all out every day. 🙂 They had us do some HIIT workouts and they were fun!

  14. JennP on October 10, 2012 at 12:02 pm

    His name is Len Kravitz?? That’s awesome. I’m not sure what he looks like, but I’m betting he doesn’t get confused too often with his rock ‘n roll namesake.

    • Fitnessista on October 11, 2012 at 12:54 am

      hahaha no they look a little different

  15. Angie on October 10, 2012 at 12:04 pm

    When I did HIIT that was the only time I actually lost weight. I find it to be the most effective form of working out.

    • Fitnessista on October 11, 2012 at 12:54 am

      science backs it up too! hiit is awesome 🙂

  16. Hanna on October 10, 2012 at 12:15 pm

    How many times should you do HIIT a week?

    • Fitnessista on October 11, 2012 at 12:54 am

      max 3 on non-consecutive days

  17. Jackie L on October 10, 2012 at 12:16 pm

    AWESOME post! I love HIIT training and have been going to a boutique fitness studio in NYC, Refine Method, that teaches classes in this way, since April. HIIT training at Refine has made me so much stronger which i love!

  18. Sarah dawson on October 10, 2012 at 12:50 pm

    i’d like some ideas as to how to implement hiit if i’m not a runner (need lower impact) and can’t get to the gym for machines…is the point to just do anything working hard and then less hard alternating? Would burpees or something work? Sun salutations?

    • Fitnessista on October 11, 2012 at 12:54 am

      whatever can get your heart rate up!

  19. Holly on October 10, 2012 at 12:50 pm

    Awesome post! I’ve been wanting to do more HIIT because I know how awesome it is, but I never know how long to do it for (how many rounds) and fear not getting a good work out so I just don’t do it because I didn’t know how. This clears up a lot!

    With that said, how many days a week should you do this? Is that to say that a 45 minute run at cruising speed isn’t as effective as a 20 minute HIIT? Sometimes I just enjoy cruising along so I’m curious how this compares.

    Also, I go to spin class twice a week and we do some intervals, however it’s not strictly regimented (in other words, it’s not 30 on/15 off for a set number of times, we just do that through out the class) so do I count that as a day of HIIT and shouldn’t do a treadmill HIIT routine the next day for example?

    Lots of questions! But thank you for all the wonderful information!

    • Irene on October 10, 2012 at 1:24 pm

      I always wonder how to “count” spin class too. It seems too long to be true HIIT (at my gym all the classes are 1 hr), but it is definitely intervals, so….I don’t know really but I tend to count it as HIIT because I need a day off from hardcore exercise the next day (I do slow and steady or rest).

  20. Dani on October 10, 2012 at 12:58 pm

    Thanks for the info! What does an increase in capillaries and mitochondrial density mean?

    • Fitnessista on October 11, 2012 at 12:53 am

      it means your body can more easily transport blood to organs, and your body can more effectively burn fat through the cells

  21. Michelle on October 10, 2012 at 1:07 pm

    Great & informative post!! I love HIIT, it’s nice to get a really awesome workout in 30 minutes!

  22. Sarabell on October 10, 2012 at 1:09 pm

    How safe would you say HIIT is for a pregnant woman who is used to low-impact cardio?

    • Fitnessista on October 11, 2012 at 12:52 am

      i wasn’t comfortable doing it while i was pregnant. i wouldn’t recommend it if it’s something new to you- wait til after the baby is here

  23. Amanda @ .running with spoons. on October 10, 2012 at 1:10 pm

    Thanks for all the great info on HIIT! I used to think that the more time I spent in the gym, the better off I’d be, but ever since discovering the beauty of HIIT and interval training, I don’t think I’ll ever go back to that kind of mentality. Not only is it a whole lot easier to fit a quick workout into a busy day, but I’ve noticed it’s definitely a lot more effective as well. So yeah, big fan right here 😀

  24. Laura on October 10, 2012 at 1:24 pm

    Hi! Great post today. I am going to use one of these workouts at the gym tonight. Thanks for posting! Though you might like to join my new weekly link up 🙂 It’s called Hella Good Hon Workout Wednesdays.

  25. Irene on October 10, 2012 at 1:25 pm

    I love HIIT. I’ve been really sad I’ve actually gotten slower and less fit with all the slow and steady running I’ve been doing training for my half marathon. Luckily it is almost here and I go back to intervals and strength training with a vengeance next week!

  26. Rachel on October 10, 2012 at 1:58 pm

    LOVE this! I’ve been doing HIIT runs lately in attempts to shorten my mileage. It was a weird transition at first but I’ve already noticed changes in my body and speed 🙂

  27. Bethany on October 10, 2012 at 1:58 pm

    What method of HIIT is most effective?

    • Fitnessista on October 11, 2012 at 12:51 am

      all of them- you want to vary your training style as much as possible

  28. beingvivacious.blogspot.com on October 10, 2012 at 2:25 pm

    Thank you so much for this. This is really interesting, and I will definitely be trying some of this at the gym.

  29. Jenn on October 10, 2012 at 2:28 pm

    Thanks! totally printed your graphics for easy access on HIIT days!

  30. Cher @ Weddicted on October 10, 2012 at 3:16 pm

    What a great and informative post – thanks! I prefer HIIT, rather than continuous cardio, because I like to have my workouts finished in a short amount of time, and sweating like a maniac proves (to myself) that I actually did something worthwhile!

  31. Meredith on October 10, 2012 at 4:51 pm

    THANK YOU, Gina for putting together this round-up! HIIT is everywhere you look these days, but I haven’t yet come across a comprehensive overview like this that has both sample workouts AND the science and information to explain and give context. You’re the best. Especially love the easy-to-read graphics for the different workout options.

    I have some questions re frequency of high-intensity exercise, but I’ll email you directly. 🙂

    • Fitnessista on October 11, 2012 at 12:49 am

      i’m excited to read it- happy to hear you enjoyed the post

  32. Diana on October 10, 2012 at 5:38 pm

    All your posts on how HIIT really does work has motivated me to try your routines. I’ll let you know how it goes

    • Fitnessista on October 11, 2012 at 12:44 am

      please do!

  33. Meghan @ After the Ivy League on October 10, 2012 at 5:46 pm

    I was really into HIIT a few months ago, but I think I was actually doing it too often! I want to work on incorporating some HIIT treadmill work into my cardio workouts again, but I definitely need to decrease it to 1-2 times/week. I love the info in this post, definitely marking it for future reference! Thanks!

  34. Emily Stember on October 10, 2012 at 6:42 pm

    Thank you so much for this post! And for including the workouts! I’m going to strive to do at least two before the week’s end. I’ll tweet you about how it went! 😉 You always have the best workouts on your blog and I love that you include background information! Thank you!

  35. Erin @ Girl Gone Veggie on October 10, 2012 at 7:51 pm

    I need to incorporate more HIIT in my workout, it just hurts so much after I do it I always get a little wary.

  36. Hillary on October 10, 2012 at 8:07 pm

    I love HIIT for keeping boredom at bay—it’s an easy way to challenge myself and keep it interesting!

  37. Jayme on October 10, 2012 at 8:12 pm

    Thank you for the great graphics. I save them on my phone and pull them up when I need an idea while at the gym. I love HIIT workouts– I feel so great afterwards.

  38. mountain girl heidi on October 10, 2012 at 8:44 pm

    I’m excited to start incorporating some of these workouts into my life post-50K. I feel like I’ve turned into a slow slow slow running machine (more blob than machine), and I need something to get my heart pumping again and the weight down. And to rejuvenate my workouts! Thanks for this!

  39. Bek @ Crave on October 11, 2012 at 2:49 am

    Thanks for this! I’m actually saving this to my computer for future reference. I’d love to incorporate more HIIT into my workout but the problem is I enjoy my continuous cardio group fitness classes too much. I guess, when things change and I have less time I can definitely use it to get a quick workout in!

  40. Cassie on October 11, 2012 at 3:11 am

    Love this post! I teach classes often like you, so my workouts revolve around Group X schedules and it’s easy for my body to get used to it and plateau, but as soon as I throw HIIT into my non-teaching days, results are back. I enjoyed some fitnessista-inspired HIIT last night in my hotel while I’m travelling – it’s great to get in and out of the gym in a short amount of time but still have an awesome workout.

    Is there a wrong way to do HIIT? I have a few different intervals set on my Gymboss app, but I mostly use Tabata or 1:30 work, :30 rest. I like it because I never get my breathing too slow before I go again, and when using a machine, it also takes time to increase/decrease speed/resistance, so 30 seconds work feels too short. It looks like Dr. Kravitz’s methods are all equal or more time resting though. Should I decrease my work time?

    Thanks for the great info!

  41. Stellina @ My Yogurt Addiction on October 11, 2012 at 8:44 am

    I love HIIT training! I usually do treadmil workouts with by making up my own HIIT routine to beat the boredom. I am definitely bookmarking this page! Thanks for the ideas, and cute graphics! Love your blog Gina 🙂

  42. The Healthy Hostess on October 11, 2012 at 1:36 pm

    Hi Gina!
    I had the privelage of hearing Dr. Kravitz speak last year as well and was so impressed with his “mad scientist” approach to exercise. He was an amazing presenter and his ideas were so interesting to learn about – how he tested and what didn’t work. Love the recap!
    What program do you use to make the charts? I have a few charts I need to make for clients and would love your input!
    Thanks so much!

  43. erin on October 11, 2012 at 2:02 pm

    please tell me the title of this post is a nod to “crawl the warrior king” aka how to lose a guy in ten days, ha!

  44. Erica @ Love the Leap on October 11, 2012 at 3:27 pm

    Turbofire actually introduced me to HIIT training about 3 years ago and I’ve loved it ever since!!! It’s a great way to incorporate some cardio into my strength days and has made a world of difference! Great post 🙂

  45. Kara on October 11, 2012 at 7:37 pm

    Hi Gina,
    I recently quit the gym because I pretty much dreaded going, even though I love staying fit. I was just sick of getting on an elliptical or doing the same weightlifting routine every time. I’ve been doing yoga (vinyasa and hot) and running. Do you have any suggestions for different types of HIIT workouts without the gym?

  46. Sheldon on March 13, 2013 at 5:31 pm

    what exactly is HIIT workouts, I apoligize I missed it somewhere?

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