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Exercising in the Cold of Winter by Allen Lim

Posted on January 17, 2013 by Skratch Labs

So far, every time I’ve gotten on a plane this year, I’ve flown to somewhere colder than where I was previously. I started the year in Los Angeles, leaving LAX at a nice balmy 70˚F, before heading back home to Colorado where temperatures were a cold but manageable 40˚F. Unfortunately, things started really getting tough when I headed out to spend the week in Verona, Wisconsin for the Cyclocross National Championships, where we brought the Skratch Lab’s kitchen trailer to cook for racers and spectators. I knew it was going to be cold heading out, but working in 20 to 30˚F temperatures all day was a harsh reminder of all of the challenges and risks associated with exercise and exposure in sub-freezing temperatures.

While I’ve spent a large part of my career thinking about how to improve performance in hot weather conditions, the reality is that humans are extremely well suited to cope with the heat. When it gets hot, we easily and effectively redirect blood flow to help dissipate heat to the skin, we sweat to help cool that skin, we make quick hormonal adaptations that increase our ability to hold and store water, and we become more efficient at this whole process the more we are exposed to the heat. 

In stark contrast, humans have very few and fairly unsubstantial responses to the cold. Blood vessels can clamp down to help keep warm blood at the core, we might shiver to increase our metabolic rate, and for some individuals, after consistent exposure to the cold an increase in the core temp during exercise or an input of heat into the core can cause blood flow to increase to the hands and feet helping to keep the extremities warm despite the cold – something known as the “Hunter’s Reflex.”  These responses, however, do little to actually keep us from losing precious body heat. Unlike some animals, our fur is limited and we can’t just burn fat to create heat, so our only real option for preventing hypothermia or other cold weather related injuries like frostbite or exercise-induced bronchoconstriction depends on our behavior and technology.

When we exercise in the cold, we might be creating extra heat, but the combination of sweat, movement, and an increased ventilation rate can create some real problems. Ironically, one of those problems is the loss of even more heat and the risk of getting too cold once we stop exercising because of excess moisture from sweat. In fact, Eric Larssen, who we supported on his recent attempt to ride to the South Pole, faced temperatures in Antarctica that were so cold that he had to find an exercise intensity that was just hard enough to keep his bicycle moving, but easy enough that he would minimize any sweat production or risk freezing when he stopped.

That extra heat production from exercise and the ease at which we can lose that heat in the cold also puts extra strain on our fuel stores. In particular, when exercising in the cold, we preferentially rely on carbohydrate in the form of stored glycogen. A lot of that is due to an increase in our fight or flight response – activation of our sympathetic nervous system that works in the background without conscious attention to keep us charging under stress. Cold as a basic stress causes our sympathetic nervous system to light up which can cause us to waste precious energy, especially carbohydrate, making it a lot easier to bonk or hit the wall in the cold. Despite having ample fat stores available to us, once we run out of carbohydrate, we risk becoming hypoglycemic (low blood sugar). Since our nervous system and brain rely solely on glucose (i.e., sugar or carbohydrate) we can get really loopy when that happens. While becoming hypoglycemic at any temperature is bad enough, becoming hypoglycemic and hypothermic can be even worse since in and of itself, hypothermia can also lead to a host of issues like confusion, apathy, irritability, and cardiac arrhythmias. Thus, making sure we have plenty of food available, especially simple sugar, can be a lifesaver when it’s cold or when we get cold.

            This increase in sympathetic tone can also result in something known as cold diuresis. Essentially, when we’re cold or exposed to the cold we pee – a lot. As our sympathetic tone increases, it causes our blood vessels to stiffen which increases our blood pressure. At the same time, the cold causes blood vessels in our skin and periphery to constrict which drives more blood to our central blood volume further increasing blood pressure. This ultimately causes our kidneys to respond by pushing out dilute urine into our bladder and inadvertently dehydrating us even if we previously drank enough.

Another issue is that cold air is extremely dry air, which can damage our delicate lungs which function best when the air we breathe is brought up to 100% humidity and to body temperature (37.0˚C / 98.6˚F).  This is easily done at warm temperatures, but at a given relative humidity, the colder the temperature the less water the air holds. As an example, at 100% relative humidity, there is 44% less water in the air from 0˚C compared to 10˚C (5 grams of water per liter of air versus 9 grams of water per liter of air). So when people say “it’s too cold to snow” it probably is too cold to snow since the air can’t hold the moisture. The net result is that as the temperature drops, we lose more water and heat through our lungs to humidify and heat the air we breathe. Specifically, depending upon the humidity, at 0˚C (32˚F), we can lose anywhere from 20-30% more water through our lungs compared to 20˚C (68˚F), and from 40-50% more water compared to when the temperature is at 30˚C (86˚F).

At rest, when our ventilation rate is only about 5 liters of air per minute, the amount of water we lose through our lungs is fairly insignificant - about 10.5 ml of water per hour at 0˚C and 6.5 ml of water per hour at 30˚C. But this small amount can become a really big deal when we are exercising and ventilation rates can be as high as 100 to 150 liters of air per minute. At a ventilation rate of 100 liters per minute, we can lose as much as 211 ml of water in an hour at 0˚C through our lungs versus 132 ml of water in an hour at 30˚C. This difference isn’t trivial since in many cases, our lungs can’t actually keep up with this differentially and the air we breathe isn’t fully brought up to temperature and humidity in the lower airways. This can lead to inflammation, damage to our airway structure, and a higher prevalence of exercise-induced bronchoconstriction and asthma in the cold winter season – something that can be worsened by dehydration or inadequate fluid replacement in the cold.

 The question, however, is if all of this actually adds up to real dehydration in cold weather. While there are obvious risks of not getting adequate fuel and hydration in the cold and while there is a good rationale for how one might be at risk for becoming dehydrated in cold environments, there’s not too much research on hydration status in cold temperatures. This may be due to the fact that it’s not actually a problem and not something that we either worry about or study. But, that lack of attention may also be a problem in and of itself. In fact, in a recent study examining hydration status and sodium balance in a group of junior women’s soccer players in a cool environment, the players did not drink enough or consume enough sodium despite very low sweat rates (Gibson, et al. 2012). In another study, that examined water turnover and core temperature on Mt. Rainier, researchers found that hydration demands during the ascent in a group of seven novice climbers was elevated and that the climbers lost a significant amount of fluid despite not showing an elevation in core temperature (Hailes, et al. 2012). In both situations, dehydration occurred despite a lack of a heat stress and perhaps because of a lack of drive to drink due to the cold. Because, even a small amount of dehydration can hurt performance (Yoshida, et al. 2002), it stands to reason that staying focused on hydration, even in the winter, can help improve one’s performance.

With all of this in mind, it’s obviously important to first and foremost do everything you can to stay warm when temperatures are cold. For the most part, much of this comes down to our behavior – to being prepared and having the right gear if you’re planning to head out and exercise in the cold. Investing in the right clothing is obviously the first place to start – a high quality and tight wicking base next to the skin, an insulting wool over that, high loft materials for extra warmth as another layer of defense, and a final barrier to stop the wind on top. Add to that gloves, a good neck gaiter, something to cover your face and create a barrier to help maintain moisture lost through breathing, good head protection and booties to keep your feet warm.  Also, instead of putting air activated toe and hand warmers around your feet and hands, try putting them next to your chest and see if that “Hunter’s Reflex” works for you.

Beyond the right clothing, it’s just as important to focus on your food and hydration in the winter as it is anytime of the year with some subtle differences. First and foremost, realize that your need for carbohydrate at any given intensity is probably going to be higher when it’s cold. So don’t forget to eat and to bring those simple sugars outdoors with you. Next, just because you may not sense that you are losing a lot of fluid or you may not feel that you need to drink, making sure you stay on top of your hydration, especially with something warm. It’s a lot easier to keep your core temperature up from the inside out than it is from the outside in, so having an insulated bottle and keeping some warm hydration product can be a small but significant thing. This is one of the main reasons we decided to develop our Apple and Cinnamon exercise hydration drink mix. We wanted something that would taste good hot and that would remind us to bring something hot out with us that had some calories and electrolytes in it for exercising in the cold.

Finally, use common sense. Sometimes it’s best to just stay indoors and go to the gym, get on a treadmill, or ride the trainer. Be smart out there and use your head. In cold weather, it’s really our best tool.

For more on the topic, check out the references below:

Gibson, J. C., Stuart-Hill, L. A., Pethick, W., & Gaul, C. A. (2012). Hydration status and fluid and sodium balance in elite Canadian junior women’s soccer players in a cool environment. Appl Physiol Nutr Metab, 37(5), 931-937.

Hailes, W. S., Cuddy, J. S., Slivka, D. S., Hansen, K., & Ruby, B. C. (2012). Water turnover and core temperature on Mount Rainier. Wilderness Environ Med, 23(3), 255-259.

Kippelen, P., Fitch, K. D., Anderson, S. D., Bougault, V., Boulet, L. P., Rundell, K. W. et al. (2012). Respiratory health of elite athletes - preventing airway injury: a critical review. Br J Sports Med, 46(7), 471-476.

Marek, E., Volke, J., Muckenhoff, K., Platen, P., & Marek, W. (2013). Exercise in cold air and hydrogen peroxide release in exhaled breath condensate. Adv Exp Med Biol, 756, 169-177.

McMahon, J. A., & Howe, A. (2012). Cold weather issues in sideline and event management. Curr Sports Med Rep, 11(3), 135-141.

Sue-Chu, M. (2012). Winter sports athletes: long-term effects of cold air exposure. Br J Sports Med, 46(6), 397-401.

Yoshida, T., Takanishi, T., Nakai, S., Yorimoto, A., & Morimoto, T. (2002). The critical level of water deficit causing a decrease in human exercise performance: a practical field study. Eur J Appl Physiol, 87(6), 529-534.

(2011). Update: cold weather injuries, U.S. Armed Forces, July 2006-June 2011. MSMR, 18(10), 14-18.

This Week at Skratch Labs

Posted on October 25, 2012 by Skratch Labs

Well, it finally happened.  We got our first snow of the year here in Boulder and, try as I might, there’s apparently no amount of denial that can convince me that summer is not truly over. I suppose it had to happen eventually.  And while I know the colder days and longer nights will make it a bit tougher to keep putting in the miles, I’m determined to not let it stop me entirely.  Who knows, with winter coming, maybe we’ll even slow down a bit here at the offices and get a chance to catch our breath.  But if the past nine months are any indication, I probably shouldn’t count on that.

A couple folks I know for sure won’t be getting a break any time soon are our founder, Allen, and Ian, our CEO.  Allen’s been jetting around the country doing super cool stuff as per usual as you'll see below, so no rest for him, and Ian happens to be in his final semester of engineering school while also running our company, so I’m guessing there won’t be much respite in the near future for him either.  Talk about having a full plate...

Allen took a quick trip to Chicago to meet Michaela Kiersch, one of our new ambassadors earlier in the week.  He spent the day getting to know her, watching in awe as she displayed her unique version of urban “rock” climbing by conquering all sorts of structures on the south side of Chicago, and, if this was the same Allen I’ve known for twenty years, waxing philosophic about life, love and everything in between.   We’ll share more about Michaela and let her tell you her story in the months to come.  We’re all very proud to have her as one of our first ambassadors and we’re excited for you to meet her.

After that stopover in Chicago, Allen met Biju in Atlanta to help hydrate and feed the Dempsey Racing Team and their crew at the Le Petit Le Mans auto race.  They clearly passed over into the Bizarro world because Patrick was asking to take pictures with them.  Is it me or does that seem a little backwards?  

After that, Allen was off to North Carolina to consult with the gang at Joe Gibbs Racing.  And if you think auto racing is just about driving really fast in a circle, well, Al can tell you there is heck of a lot more to it than that.  The British Cycling Team has McClaren for research and development?  Fine.  We’ve got NASCAR.  Sounds nuts, right?  We’ll see.

Back at home it was business as usual for the most part.  Orders came in, orders went out.  We do our very best to get everything out the same day it comes in so you don’t have to wait any longer than necessary for your Skratch.  (Quick tip- if you can have your order shipped to a commercial address, you’ll save as much as 25% on shipping via FEDEX Ground.)   Our events manager Jon brought his new puppy, Penny, in.  She is, what’s the word I’m looking for… adorable.  We had our daily Knockout games on the basketball court out back which are typically won by order packing expert Julian and, sadly and as usual, Jason kept clobbering me at Ping Pong.  Just another day at the Skratch Labs office. 

Remember up top how I said I’m determined to not let the cold and the dark stop me from getting my miles in?  So far, so good.  I’ve been taking the long way to and from work a few days a week on my cyclocross bike. Here’s the thing about the CX bike:  Funnest. Thing. Ever.  A straight shot on the bike path would be about three miles each way, but I usually rack up between fifteen and twenty as I explore as many different routes as I can find.  Dirt trails, levees, alleys- all are fair game on the CX bike. My rule is that I never take the same way twice.  And now that I'm riding home in the dark, even the same old routes seem completely different.

And look, if Tim Johnson is going to leave his Sweet Ride (Cannondale SuperX Hi-Mod Disc!!!) at the Skratch Shop for two weeks while he’s in Europe, then I'll just have to assume it’s because he knows it’s my size.  But that’s a story for another day.  Ok, I gotta get ready to ride to work in the snow tomorrow. Please don’t tell Tim. 

Aaron

Skratch Labs

How sweet is this ride?

Pretty Sweet.

The Travel Kitchen - How you can eat well while traveling

Posted on July 02, 2012 by Skratch Labs

 Last time I checked in with the Skratch Labs blog, I had suffered a minor meltdown in Las Vegas on my way to Redlands, and vowed to never again be subjected to the disaster known as the “average American meal” as I traveled from race to race.  After I got back home, Allen decided I needed a few more key pieces in addition to the rice cooker, so we went to procure supplies for the Skratch Labs Mini Kitchen.

The Mini Kitchen is the result of a paradigm shift in the way athletes care for their nutrition needs.  It has always amazed me that people will spend thousands upon thousands of dollars on equipment, only to shovel garbage down their throats right before a race or skimp on the quality of the food they eat.  Skratch Labs and The Feedzone Cookbook are both founded on the premise that conventional wisdom isn’t very wise, and that simple solutions are often better than their pseudoscientific counterparts.  In the same way that there is no advanced technology behind an ice-sock on a hot day, or that the ingredients in a rice cake are far fewer than almost any energy bar, the marginal gains to be had by bringing a rice cooker (and few other bits) to a race are easy to take and low tech.  It’s a cheap and simple insurance policy that means you will have familiar food at competitions.

The Mini Kitchen is also contagious; after the upgrade to the equipment, I started cooking for my team at races.  It became a way for me to relax; I could both control what we were eating, and it took my mind off the race by giving me a task to complete.  What I didn’t really expect was for my personal paradigm shift to start affecting the other riders on the team; I thought I was the picky, weird guy on the team who would always shut down restaurant options, but I started to notice the others catching on.  When I showed up to Tour of the Battenkill, I found that one teammate had brought his own rice cooker in case I hadn’t brought mine.  As we coordinated to drive to Tour of the Gila, the only question he asked me was whether he needed to bring his cooker or if mine was enough.  The early riser on the team learned how I make oatmeal in the cooker so that he could start a massive batch for the team each day.  I’m currently guest riding for a team at Tour de Beauce, and I expected raised eyebrows when I said I brought a rice cooker, but after I gave a few guys honey and almond butter rice cakes, they all thought it was great.

So what are the essentials?  My crucial tools are pretty limited, but most of my races have host housing, so that makes things considerably easier.  In addition to a 6 cup rice cooker (3 cups is ok for one or two people, but a team needs the grown-up version), I always have a rice spatula, a small, lightweight brownie pan for forming rice cakes, a roll of foil or Martha Wrap, a knife, a bag of rice, a bag of oats, some nut butter, honey, and dried fruit.  Those things will get you through, but if you need more heat and variety, an electric wok/frying pan or a small George Foreman grill will make just about anything you need to compete.  It all can stack inside itself in your suitcase, and doesn’t really add that much to your traveling weight, but it makes a huge difference in your confidence and comfort. 

The Mini Kitchen has already paid itself off in the first two days of Beauce.  No lunch after the race? No problem.  Only gels to eat?  Not now, I have rice cakes.  Again, I expected to be the strange foreign guy on the team, but everyone seems to agree with the value I put on these tools.  Now if only teams will get with the program! - Julian Kyer

Rice Cakes - Blackberry mint with a chocolate center!

Posted on June 12, 2012 by Skratch Labs

Here is how Allen made these rice cakes this morning...let us know how they work for you!

5 Cups sushi rice, rinsed and cleaned

7.5 cups water

2.5 small boxes of Blackberries (you know the little square boxes from the supermarket)

1 box of fresh mint (yeah, almost the same little box from the supermarket but not square this time, more rectangular)

1 lemon

1/4-1/2 cup sugar (but we're not really sure how much b/c we just poured it on until it tasted good)

1 cup chocolate chips

Directions: cook the rice, julienne the mint, squeeze the lemon on top of the mint in a large bowl and then add the sugar, mix the sugar, rice, mint and blackberries, take half of this mixture and press into the bottom of a cookie pan, put the choc chips on top of this layer, add the rest of the mixture on top of the now melting choc chips, cut and serve just like the video below!

Prototype Rice Cakes

Posted on May 23, 2012 by Skratch Labs

Rice cakes.  They're the new black.  At least in the world of nutrition conscious athletes they are.  And while our cookbook The FEED Zone has recipes for a variety of delicious rice cakes to suit every pallete, Skratch Labs founder Allen Lim is always looking for the next thing.  Because just because you find a better way, doesn't meant there isn't something even better than that.  Enter Apple/Cinammon Rice Cakes.

Allen whipped up a batch of these at the shop a few weeks ago and they disappeared in a hurry. They're great for vegetarians or anyone who just wants a little variety in their rice cake arsenal.  The flavor is somewhere between apple pie and apple-cinammon oatmeal and we're pretty sure this new super-secret rice cake recipe isn't going to be a secret much longer.  And we're just fine with that.  Let us know what you think after you've tried them.  

Super Secret Apple/Cinnamon Rice Cakes

Servings 10-20
Time ~30 minutes

2 cups uncooked Calrose or other medium-grain “sticky” rice
3-3.5 cups water
2 apples
1 tablespoon cinnamon
brown sugar
sea salt

1. Combine rice and water in a rice cooker.
2. While rice is cooking, peel, core, and dice the apples.
3. Toss them in a bowl with the cinnamon. Add brown sugar. Add salt to taste.
4. Combine the apple mixture with the rice.
5. Press mixture into an 8 or 9 inch square pan to about 1 1/2 inch thickness.

Cut and wrap the individual cakes. Makes about 10 rice cakes. Enjoy!