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Bikram Yoga Sweat: Stumping the Rocket Scientists.

It started innocently: one day the Bikram Yoga room felt a little cool and I had come to get my sweat on! C’mon. What was going on here? This is Bikram Yoga. You know, the “torture chamber.” Here I was, being tortured by a cool breeze and goose bumps.

What to do? Add clothing. Problem solved.

If you haven’t practiced any sort of hot yoga, here’s the quickie summary: by adding heat and humidity, the body becomes more flexible, and the workload increases. The heart rate goes up and the sweat trickles down. In a nutshell, the higher the heat and humidity, the harder the class is. All 26 poses in the 90-minute Bikram Yoga sequence are beginner poses with very little movement. Without excruciating heat and humidity, it’s a cakewalk (or in Bikram parlance, a blueberry cheesecake walk). 

bikram sequenceGET HOTTER

I now come prepared to any hot yoga class. I have layers to add if the room isn’t up to snuff.  But, over the years teachers have bristled at this behavior. “Get your head out of the heater Erin.” Not so easy. I am there to work hard. The heat, humidity, AND poses deliver. ALL three. This yogi can’t balance on a 2-legged stool.

THE SCIENTIFIC CHALLENGE PRESENTED

Recently a teacher sent me a link to a WebMD article suggesting that layers, once wet, will make me feel cooler NOT hotter. The article specifically says “wet clothing greatly increases heat loss through conduction and evaporation.” What?? How could this possibly be? Shouldn’t my sweat warm up in that heat box? Adding layers, trapping heat, covering the skin…all of these strategies should keep me warm, right? Even when I sweat?

The Bikram/Hot Yoga environment is unique and articles like the one just mentioned don’t apply. The WebMD article is talking about temperatures under 68F (not Bikram). We all know wet clothing makes us cooler when the surrounding temperature is lower than our body temperature (think wet swim suit). But this is not the case in a hot yoga room. So we begin to dig.

Our athletic-minded traveler research team could not find ONE article, study, or research piece that dealt with OUR SPECIFIC situation: 105+ degree heat and relative humidity of 40-50% AND the desire to be hot…even hotter. We even went beyond the “research.” We contacted no fewer than 10 experts – in thermophysics, human performance, exercise science, neuromuscular function, and even a few authors of exercise physiology textbooks. Two dropped the ball, a few missed the point of contention (with ONE exception), and those that did reply gave us migraines with a bunch of scientific gibberish that said nada. Had we stumped the rocket scientists?

Let’s first get you up to speed about the body’s cooling mechanisms (thermoregulation). Understanding these basics is important.

BODY COOLING

  1. Radiation: transferring heat from one mass to the other without physical contact. Ever stood next to someone who just got done with a tough workout? They’re radiating heat! No need to touch…it’s coming off them like an oven with the door open.
  2. Conduction: losing heat through physical contact with another object or body. If you’ve ever sat on a freezing cold metal chair, then had the area under your butt become warmer, you’ve transferred the heat from your body to the cold metal chair.
  3. Evaporation: losing heat through the conversion of water to gas—SWEATING.
  4. Convection: losing heat through the movement of air or water molecules across the skin. This helps conduction and evaporation. Heat loss from convection depends on airflow across the skin. If you’re in a gym with industrial fans blowing, or in a Bikram studio with air movement, convection kicks in and you should cool down.

Now, let’s apply the above to working out. 80-85% of cooling during prolonged exercise comes from evaporationSWEAT! In humid environments like a hot yoga room, evaporation is slowed because the air already has a high level of moisture in it. There’s less “room” for the sweat to evaporate into the atmosphere. So if the body can’t sweat as efficiently, guess what? You feel hotter!

So when you’re in a Bikram class, with temperatures in excess of 105° F and relative humidity between 40-50%, it’s going to affect thermoregulation. With constant heat radiation from yogi to yogi, high humidity preventing sweat evaporation, and little to no airflow across the skin, it should be as easy as child’s pose to stay warm in class. But most Bikram Yogis don’t want warm. They want HOT.

 THE LAYERING QUESTION

  1. Does adding layers work? Yep. More layers should mean an increase in body temperature, especially in hot and humid Bikram studios.
  2. Do clothes curtail the evaporation process? Likely. All clothes get wet quickly due to the humidity. Could those wet clothes actually cool the body? Only if a strong gust of wind is blowing. It’s still likely the cooling is no more than bare skin and most likely less.
  3. Are we better off wearing as little clothing as possible? Not if you are trying to up the workload.
  4. How about adding as much clothing as possible? Go ahead! People will think you’re a bit “loco.” 

So listen up YOGIS:  Nah, nah, nah, na, nah, nah…We are RIGHT. Yes, a little childish…but hey we spent a LOAD of time on this! 

Our review of research (over 48 studies on MEDLINE) and email conversations with scientists suggests that layering WILL increase the workload because the body's evaporation is slowed. Along with studies that suggest this conclusion, a professor of neuromuscular function at Colorado State University corroborated our findings that layers of clothing reduce evaporative cooling (which accounts for 80-85% of the body's cooling during exercise). Hooray! He understood our question because he understands Bikram yoga!

The studies we found aren’t perfect. They don’t address heat, humidity, exercise, AND wanting to STAY WARM! Every study assumes you want to cool the body.

RESEARCH SUPPORT

  1. Sports Medicine (2003) says layers impose a barrier and in warm temps, increases body temp during exercise and slows evaporation. BINGO! BUT, what about wet clothing? Hmmmm…
  2. Another study (AIHAJ 2002) looked at clothing ventilation and thermal insulation. The results? More airflow through the clothing, the cooler the skin. Am I supposed to wear a garbage bag to class now vs. the “wicking” materials present in nearly ALL sport clothing?
  3. A study out of China looked at heat strain while wearing different ensembles for varying workloads. Simply put, you need to restrict sweat evaporation and exercise to increase heat strain and heat production.
  4. In a 1995 article from Ergonomics, protective clothing impeded heat exchange through sweat exchange for those working in hot environments. But…the specifics of “protective clothing” were not shared, so there’s no way to tell if it’s something we wear already!

Bottom line is this: those teachers who say layers can cool you down can zip it! Unless a constant breeze is blowing through the room, this just isn’t true. Those teachers that want you to get your “head out of the heater” should do the same. It’s all about personal preference, and if there’s a need to increase my heat, so be it. If I’m fine with the increase in workload, it’s my option to add layers. Bikram yoga is about the heat…it’s the honest truth. Those schools that coddle students with fans and open windows are missing the point, and we would guess they’re missing business too.

** This article was written by Daniel Gaz and Erin Kaese. Along with Dan's clinical research work at Mayo Clinic, he is also a contributing editor to Athletic-Minded Traveler. Erin Kaese is Managing Editor of Athletic-Minded Traveler and a Bikram Yoga "loca."

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Comments

Comments

Erin- I found your article to

Erin-
I found your article to be well written and informative. However, I find the idea that bikram asanas are easy beginner postures a little disheartening...
I mean, I know it's true, but I can't, after hundreds of attempts, do standing head to knee....
Maybe I need some more clothing.

David, There are over 80

David,
There are over 80 postures to choose from in regards to Hatha yoga, so some will undoubtedly complement the others; Bikram chose this sequence to represent his best understanding of how to bring blood flow to every portion of the body. Particularly, the standing series has many different variations for sequencing for specific needs. As a tip, if you can't finish the posture, then your setup or initial movements are being overlooked- (in this case, its not your head to knee, its your concrete leg your standing on that deserves the focus-probably across a few different postures). I found that in standing head to knee, that the feeling in the back of the knee of the posted leg is exactly the feeling I'm searching for in the clasped knee with the toe up. Actually the finishing touches of head to knee with the heel flat and rising can best practice with its complement, 3rd from last, sitting head to knee. In the sitting version, I noticed if I focused on the alignment of my spine it allows my diaphragm access to the deeper hip and pelvic muscles/ligaments that will support your standing series.

Like all good things, it will

Like all good things, it will come to those who wait. Or in the case of yoga, practice the asana of patience. You make an excellent point @ the standing head to knee posture: it takes balance, strength & flexibility. We'd call that the Yoga trifecta.

Cheers.

This was a very interesting

This was a very interesting article to read and I enjoyed it. I am a track runner and running in layers whether it being cold or hot is good for your body and muscles. This is something that track runners or any kind of runner is use to doing. I actually warm up in sweats and long sleeves right before races whether its hot or cold outside and take them off before the race. After my race is finished I put them right back on and do a cool down. This keeps my body and muscles warm and prevents me from injuring myself. It does take time to get use to especially if youre from down south where it is extremely hot and humid out in the summer, but I think its very beneficial to atheletes! In general this article was interesting and Im thinking about taking a yoga class at a gym but maybe not so much in layered clothing! :)

This article is very

This article is very interesting. I have never tried yoga, but after reading this article, I think I just might. I agree that adding layers will help increase sweating (many wrestlers do this to help drop weight). Being warm would definitely enhance the stretch, hence, causing for a better workout.

This article was very

This article was very interesting and I do agree with it 100%. Layering up does increase the workload and you can use this method in other forms besides Yoga. Boxers are notorious for this method as well as people who are trying to lose weight. I've tried this method before and It is very intense and I was not a fan of how hot I got during my workout. It is definitely something you will have to get used to.

In the article titled,

In the article titled, ‘Bikram Yoga Sweat: Stumping the Rocket Scientists’, I would agree with the conclusions made by Erin and Daniel. The idea of adding layers of clothing to make your hour of Birkram yoga challenging in the context of true Birkram yoga makes complete sense, even if you do not understand all of the thermodynamics jargon. Is this a concept worth investigating? The Scientific challenge presented suggests from the WebMD article stating that layers, once wet, will make me feel cooler not hotter, and specifically says, ‘wet clothing greatly increases heat loss through conduction and evaporation” (Kaese., 2013). These ideas leave more questions than answers and I have reservations whether the folks from WebMD have ever tried exercising and perspired. Does the WebMD article have anything to do with layering and the idea that it would create a more challenging experience? What is the context of the suggestion,’ wet clothing greatly increases heat loss through conduction and evaporation’, is this in the context of layering? This seems to be what is in question here, and the point of the article, right? Their implication that suggests once wet, you will feel cooler than hotter (assuming you are layered), I completely disagree with. It has been my experience whether it is 20 degrees or 100 degrees, once I am hot and perspiring, keeping my layers on will continue to make me feel hot and the exercise of choice becomes taxing, despite how wet I become. I say yes then to Erin’s question that adding layers will trap the heat and keep you warm even when you sweat and challenging too!
Based on my experience of living in the heart of the Sonoran desert in Tucson, Arizona, trying to do anything in the heat, similar to what you would experience in a Birkram yoga class is difficult, sweaty, and un-enjoyable. I do not understand why anyone would enjoy exercising of any kind, in those kinds of temperatures and humidity. This is not to say I don’t enjoy sweating, pick your poison be it Birkram Yoga or my personal favorite running on the Oregon Coast on the sandy beach. I guess you could say Birkram yoga is not my thing, I am more of an, ‘Adeline Junkie’, who wants to get my fix by running, or sweating my butt off in spin class. The few times I have tried regular Yoga, I have enjoyed the experience immensely and found it to be challenging, rejuvenating, and that is all I needed. If Birkram yoga is your thing, I say go for it!

Kira, Try Bikram. Just to

Kira,
Try Bikram. Just to check it off the exercise modality list. There are so many...Also LOL on your comment about whether the "folks at WebMD have ever tried exercising and perspired." :)
We love the Oregon coast too...and the mountains.

Very interesting article. I

Very interesting article. I have some experience in teaching Vinyasa and Ashtanga Yoga, but have never had the chance to try Bikram Style. In my classes I encourage students to wear some loose outer layers to stay warm durning the beginning and especially the end of class. In Ashtanga yoga you work hard and fast, with the continuous flow you can "work up quite a sweat". Layers help keep the body from cooling too fast during the relaxation at the end of class. I will have to try leaving layers on during class and see the effects of the added clothing for a full class.
I also wonder how the new "wicking and quick dry" clothing effect the process of evaporation. Being a skier, my "first layer" is a wicking quick dry material to remove water away from the body to keep me warm. Yet in scuba, the idea is to trap the water between the wet suit and body, insulating the water trapped to keep the body warm. I guess the next question could be does the type of fabric make a difference in cooling or insulating?

The type of clothing will

The type of clothing will affect the evaporation process. Keep in mind that when you are skiing, that the air temp is much cooler than body temp and it's why keeping dry is crucial to maintaining warmth. Any dampness will create a chill. The conditions in a Bikram room are completely different...air temp greater than body temp with added humidity.

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