Smells, sweat and the lack of central air, it must be summertime in the city. I've lived in pretty much every region of America now and no summer has compared to the last two that I've had in the city. Despite the scorching hot summers of this concrete jungle that I now call home, one of my favorite things have always been to get out and go for a walk. Walking is a great form of exercise that literally involves zero equipment, doesn't require a gym membership and in my experience actually proves to be quite therapeutic. You'd be amazed at what getting out for a long walk a few times a week can do for your physique and your soul. During one of my most recent walks from my apartment in Murray Hill to Brooklyn, I got a question on my IG about why I decided to walk the hour and a half it took me to get to my destination, over just getting a quick high intensity workout in instead? Well my dear IG friend, below I've given you a short breakdown on the science behind LISS "Low Intensity Steady State" vs. HIIT "High Intensity Interval Training" workouts, which is best for you and most importantly when it's best to choose one or the other. 

LISS "Low Intensity Steady State" 

This is a cardio workout in which you spend 30-60 minutes working at around 50-65% of your maximum heart rate. Think, a jog on the treadmill or outside, a hour walk time on the erg, etc. Chances are if you're still able to carry on a conversation during this activity, you're partaking in a LISS workout. During a LISS your body is burning fat as a fuel source vs. carbohydrates. Why? Well to get science-y for a second, during LISS, as your body breathes in oxygen it combines with fat and produces energy. However, it can only do so at a slow rate and since during LISS your oxygen intake is done so at a slower pace, this process is possible. Note though, I didn't say that you're burning more fat overall, it's just that in LISS your body is burning more calories from fat. Since this is a lower intensity workout however, you're still burning less calories overall than a higher intensity workout.

HIIT "High Intensity Interval Training" 

HIIT seems to be something that more and more people are not only aware of but also openly baked into our workouts. High Intensity Interval Training typically consists of alternating between short circuits (:10-:60 seconds) of intense work and recovery periods. During this intense working period you're getting that heart rate to around 90%-95% of your max. An example of this could be a 6 Minutes of EMOM (every minute on the minute) where we program :45 seconds of work then :15 seconds of recovery. Or like a workout that I just went through in one of our B|Fit classes at BRICK New York where just the other day we went through 10 rounds of a 10 cal row and 10 Plate G2OH's ideally finishing within :60-:75 seconds so that you could rest prior to taking on the next round. During your these HIIT periods, your breathing has now intensified and is therefore too intense for the oxygen to combine with your fat cells. Therefore your body now resorts to carbohydrates as a fuel source. To get science-y again, during a HIIT our Central Nervous Systems are kicked into high gear and activates a process called EPOC  "excess post-exercise oxygen consumption," which quite simply put is the process of our body working to return to homeostasis, aka full recovery. That process within itself takes energy which means you're burning calories even after you've actually completed your workout. 


Now that you know what they are, lets compare and contrast. Going back to my walk to Brooklyn, I mentioned that it took me an hour and a half to walk a little over 4.5 miles. After my walk I looked down at my Apple Watch and it told me that I'd burned a little over 400 calories. Though I couldn't see what the percent breakdown of cals from fat and cals from carbs, I can pretty much guarantee that they were higher.  The con here though is that it took me AN HOUR AND A HALF to do so! I don't know about yall, but I don't have an hour and a half to put into a workout 5-6 days a week, do you? Additionally, I spent all that time utilizing the same muscles and joints over and over again. Over a period of time, don't you think that could cause a bit of wear and tear?

Let's now think about HIIT and I'll use the class that I coach at BRICK as an example. People that come into my class are typically working anywhere from 30-40 minutes and by the end of it have probably burned a ton of of calories and quite frankly, had their asses handed to them a bit. Imagine taking that class 7 days in a row and living to tell the story about it. Chances are you won't and that's because working at an extremely high level of intensity day after day isn't sustainable.  Personally I know that I’m guilty of thinkink that I’m superwoman however, by trying to take multiple HIIT classes a week. But the truth is we need real recovery to sustain a healthy body.   


That's kind of a trick question because truthfully, you should be doing both, but here's the caveat, you should be using them in conjunction to one another and not as replacements! What do I mean by that? Well, I've always been taught through numerous fitness experts and from seeing changes in my own body that LISS is a recovery workout and HIIT is a strength workout. Since HIIT it a form of strength work you should actually use it as a replacement to traditional lifting or in conjunction with and therefore you wouldn't even think of them as being viable replacements for each other. Maybe you like to  break your week out into 3 days of strictly lifting, 1 day of B|X or similar formatted workout then 2 days of some type of LISS workout. Or maybe you're like me and fell in love with our B|Fit class because it's a nice duo of lifting and HIIT? 

There y'all have it! At the end of the day how you choose to structure your workouts all relative and dependent on your goals, diet and overall lifestyle. Just stay moving and you'll see the results.