Blog

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 November 02, 2012 by Skratch Labs

Last week it was Winter here in Boulder and I made the mistake of trying to ride through it.  I got in some great miles but perhaps a little too many in retrospect, because this week it’s suddenly Fall again and my legs are so cooked I haven’t been able to enjoy it much.  It’s a bummer, man.  It’s been a great week for the Skratch gang though, as the outdoor basketball games resumed in full force and we’re back to being able to eat lunch outside for at least a little bit longer.  So we’ve got that going for us.

On a similar note, something very cool happened here today.  What might that be, you ask?  Is it a new flavor of drink mix? Nope.  A chicken fried rice flavored recovery drink?  Don’t be silly.  We added a real Dealer Locator to our site.  Ok, so maybe it’s not as cool as the other side of the pillow, but we’re excited about it.  Now, instead of the poorly updated, and even more poorly formatted, all-text version we’ve had since we launched, our site now has a fully interactive dealer locator that will show you all the Skratch Retailers around the country.   

Ok, so it's probably not the most exciting video in the world, but watching that map populate with all of our shops made us smile here at the office.  Check it out on our site and find the two dealers closest to you- keep in mind, they may be behind you

No surprise for Allen this week, another trip.  This time I was lucky enough to go along for the ride.  We took a quick day trip to Wisconsin to check in with our friends at the Saris Cycling Group.  Allen has been working with them for years on their Power Taps and we’re looking to partner on some new ideas in 2013. They were hosting their annual gala event to raise money for bicycle access and Jeff and Jesse made us feel right at home.  Thanks guys and we look forward to teaming up on some projects next year.  And those cheese things we had at lunch were crazy good.

As I said at the top, the weather in Boulder has been great this week.  It won’t last, of course.  Winter, beaten for the moment, will no doubt be back with a vengeance soon enough.  With that in mind, I’m off for one Last Hurrah. The fitness is fading fast and the days are getting short, but this will be the third year I do this trip and I’m expecting it to be just as epic as it has been in the past. Saturday, I fly to California for a ride from San Francisco to Santa Barbara.  Four days and about four hundred miles down one of the most beautiful stretches of road in the world, HWY 1, with nothing but a small bag on my back and a couple of old friends from college.  Should be fun.  Check in with Skratch on Facebook and Twitter starting Sunday morning for updates from the road.  And if you're in San Luis Obispo and can put up a couple of tired cyclists next Tuesday night who would be happy to cook you something delicious out of the FEED Zone Cookbook, let me know.  Seriously, I make some pretty mean Buffalo tacos, among other things.

Thanks for reading.

Aaron

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.

Rice Cakes

Posted on October 15, 2012 by Skratch Labs

Rice cakes.  They're the new black.  At least in the world of nutrition conscious athletes they are.  Our cookbook, The FEED Zone, has recipes for a variety of delicious rice cakes to suit every pallete.  We've put together this simple post to help answer some of the most common questions and even give you a new recipe to try for yourself.

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 for long.  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!

How long will the Rice Cakes stay good?

Five tips for better fueling during endurance sports

Posted on August 19, 2012 by Skratch Labs

1. Eat & Drink Early & Consistently—One of the biggest mistakes riders make is forgetting to eat and drink early and consistently throughout the day. While this is plain common sense, it‘s often disregarded on ride day—a mistake that can spell disaster no matter how well trained or prepared you are.

As a general rule, you need to replace at least half the calories you burn each hour, and you need to begin replacing those calories in the first hour if you’re going to be out for more than three hours. On a flat road without drafting, the average cyclist will burn about 200-300 Calories at 10-15 mph, 300-600 Calories at 15 to 20 mph, and 600 to 1,000 Calories at 20 to 25 mph.

Regarding hydration, on a hot day your fluid needs may be as high as 1 to 2 liters an hour. The best way to get an appreciation of how much fluid you might need is to weigh yourself before and after a workout. The weight you lose is primarily water weight, where a 1-pound loss is equal to about 16 ounces of fluid. As a general rule, try not to lose more than 3 percent of your body weight over the course of a long ride.

2. Try Eating Real Food—While there are plenty of pre-packaged sports bars and gels touting their ability to improve one’s performance, it’s important to realize that real food can work just as well if not better than expensive, engineered nutrition. A regular sandwich, a boiled potato with salt, a banana and a ball of sushi rice mixed with chocolate or some scrambled eggs can all give you the calories you need without upsetting your stomach the way a lot of sugary gels or sports bars can. In fact, while coaching teams at the Tour de France, the riders I worked with used real food as their primary solid fuel source, because it just worked better. Most of the recipes for these foods can be found in “The Feed Zone Cookbook” that I wrote with Chef Biju Thomas to promote healthful, real-food eating.

3. Don’t Just Drink Water—When we sweat we lose both water and valuable electrolytes. If you drink only water and are sweating heavily, you’ll dilute the electrolytes in your body, in particular sodium, which plays a critical role in almost every bodily function. Diluting the sodium content in your body is called hyponatremia and can lead to a host of problems ranging from a drop in performance to seizures and even death. The amount of sodium that we lose in sweat is highly, variable ranging anywhere from 200 to 400 mg per half liter (16.9 ounces). Because of this large range, it’s always better to err on the side of more salt than less salt. Unfortunately, most sports drinks contain too much sugar and not enough sodium, which caused many of the riders I worked with to become sick during long days on the bike. For that reason, we developed an all-natural sports drink using less sugar, more sodium and flavored with freeze-dried fruit. Outside of using a sports drink with more sodium, also consider eating salty or savory foods on your ride rather than just sweet foods.

4. Learn What you Need in Training—Ride day is not the day that you want to be experimenting with yourself. So try different hydration and feeding strategies during training well before the big day. As an example, simply weighing yourself on a long training ride before your big event can give you valuable information to optimize your hydration for that event. Likewise, taking the time to prepare your own foods or trying different products beforehand and then writing out a specific game plan for your drinking and feeding needs can go a long way to making sure you don’t make any mistakes on ride day.

5. Come in Well-Fed and Well-Rested—While proper training is obviously important, making sure you are well rested coming into an event is sometimes even more critical. You can’t cram training, so as you approach the big day, make sure you are getting plenty of sleep and aren’t killing yourself in training the week leading into your event. Just sleeping an extra hour each night the week before your event can significantly improve your performance. Finally, adding extra carbohydrate to your diet, and making sure you get plenty of calories the week before your event, will assure that your legs are fueled and ready to go.