Cold weather, altitude and winter sports nutrition

Training and competing in the cold is more than just bundling up in some extra layers. There are some extra challenges to keep in mind, including nutritional practices, both to stay healthy and to get the most out of your workouts or performance.

This holds true for athletes competing in winter sports and for whom the cold, even snow and ice are part and parcel of their sport; or for summer sports athletes who have cold wintery conditions to train through because of their home location.

Battling through the cold for some part of your training program is inevitable, it adds another layer of variety to how you prepare and perform. Here are some key tips to keep in mind when training or racing in the cold or at altitude.

Cold weather means additional fuelling requirements
The metabolic cost of working out in the cold is greater than that at more moderate temperatures. Our bodies need to work harder to maintain our core temperature and to humidify the air we breathe. Plus, it is often just harder work moving around in extra layers of clothing, not to mention navigating icy, wintery conditions. As conditions worsen, wind chill comes into play – being wet (either through rain or sweat from overdressing for the intensity of exercise) exacerbates heat losses further.

Lean athletes are particularly susceptible to heat loss with their greater surface area to mass ratio. The resultant increase in energy expenditure can be as much as 10-15% in the cold[1]. For many, this is actually reflected in an increase in hunger and appetite[2] and it can be easy to overcompensate – after all cold weather and comfort food seem to go hand-in-hand and most of us tend to gain weight during the winter months!

However, some other athletes hard in training, appetite can just as easily be suppressed (intense exercise suppresses appetite at least in the short term) and they need to work hard at consuming adequate calories for the demands of their training routines and fitness goals.

The cold affects substrate usage
Shivering is a physiological response to the cold and is your body’s way of attempting to stay warm and maintain core body temperature. Shivering can increase body heat production four fold and is fuelled primarily by carbohydrates stored as muscle glycogen as well as blood sugars (proteins and fats appear to be less efficient at fuelling this primary response)[3].

Metabolism of carbohydrates is upped as much as six times of that during rest while shivering, meaning that athletes who are exposed to the cold are burning through carbohydrate stores more quickly[4]. Shivering also has the effect of decreasing muscular coordination, thus impacting negatively on performance.

You’re more likely to shiver if the cold comes as a shock, either a sudden change in temperature, if you have travelled to the cold or have been caught short without appropriate clothing. But for those more acclimated to the conditions, and who have undergone repeated bouts of exercise in the cold (such as you would expect with someone who lives and trains through a cold winter), fat metabolism is actually boosted and reliance on carbohydrates for heat production decreases. This increase in mobilisation of fatty acids means that fats can become a primary energy source for body heat production in the cold. Indeed some limited research indicates that a combination of exercising in the cold can enhance weight loss efforts if diet is also controlled[5].

Hydration is an often overlooked yet key component for athletic performance in the cold
Cold weather has the tendency to reduce our drive to drink, yet fluid requirements are actually higher in the cold compared to more temperate conditions[6]. Cold, dry air leads to greater respiratory water loss and at the same time increases urinary output. The fact we are not actively or obviously sweating as we do in hot, humid conditions means we also lose that visual and tactile reminder to keep up our fluids. Cold drinks can also be unappealing when the mercury drops, further decreasing the desire to drink. Altitude (which often coincides with cold winter weather and sports) also compounds water losses through respiration, meaning athletes can quickly become dehydrated[7].

Vitamin D deficiency is a common by-product of winter
Winter for some means less time out in the sunshine. This can have a huge effect on levels of vitamin D, a fat soluble vitamin that acts as a hormone in the body. Vitamin D is essential for absorption of calcium and maintaining bone health but it is also needed for a functional immune system and deficiencies are linked with an array of health issues. Sunshine is the best source of vitamin D but dietary sources include egg yolks, fatty fish and fortified dairy foods. It’s worth athletes having a yearly or seasonal blood test to check on levels and consider supplementation if necessary.

Snow (and very cold weather conditions) often means elevation
Altitude has many physiological effects and athletes need to be aware of nutritional strategies to help reduce the impact that elevation can have on both health and performance. With increasing elevation, the atmospheric pressure of oxygen drops, making it more difficult for oxygen to be delivered to body cells, including working muscles. This hypoxic state is the cause of altitude sickness, symptoms of which include headaches, nausea, decreased appetite, lack of energy and feeling generally ‘flat’. Any athlete who has travelled to altitude has no doubt experienced this to some degree and the effects can start around 6000ft above sea level. Everyone is affected differently by altitude, but thankfully after a few days adaptations occur and most people begin to feel (and perform) better. Altitude can lead to weight loss (due to decreased appetite coupled with increased energy needs) something that hard training and/or very lean athletes should be cautious of[8].

Carbohydrates are also important as an efficient energy source at altitude. Adequate fuel for training and recovery is going to assist an athlete not only in maximizing training adaptations, but give support to the immune system and help the athlete stay healthy. Focus on including nutrient dense carbohydrate rich foods such as fruits and vegetables, nuts, seeds and wholegrains and quality dairy foods.

Iron needs are increased when living or training at altitude
With decreased oxygenation of the blood, hematological adaptations occur to try and compensate and ensure adequate oxygen delivery. For this to occur though, an athlete must have adequate iron stores. Iron deficiency is a very common problem amongst winter sports athletes as well as those living at altitude[9].

For summer sport athletes, the winter is often a period of reduced training or ‘off-season’
This can be a challenging time to stay focused and the temptations of comforting, rich dishes, combined with a lack of immediacy on the training front, can lead to unintentional or less than ideal weight gain. In these instances turn to nourishing and satisfying foods that provide warming comfort and yet aren’t heavy – soups, stews, warm drinks, roasted vegetables are all great options. Continuing some activity, even if it’s a little less structured than during competition season, or turning to a completely different winter sport activity is a good way to maintain fitness, keep motivated, even address some weaknesses or imbalances and have active fun.

References:

Jett Jr, D. M., Adams, K. J., & Stamford, B. A. (2006). Cold exposure and exercise metabolism. Sports Medicine, 36(8), 643-656.
Rintamäki, Hannu. “Human responses to cold.” Alaska medicine 49.2 (2007): 29-31.
Shephard, R. J. (1993). Metabolic adaptations to exercise in the cold. Sports Medicine, 16(4), 266-289.
Askew FW. Nutrition for a cold environment. Physician and Sportsmedicine 17: 77–89, 1989
Doubt TJ. Physiology of exercise in the cold. Sports Medicine 11: 367–381, 1991
Pitsiladis, Y. P., & Maughan, R. J. (1999). The effects of exercise and diet manipulation on the capacity to perform prolonged exercise in the heat and in the cold in trained humans. The Journal of physiology, 517(3), 919-930.
Westerterp, K. R. (2001). Energy and water balance at high altitude. Physiology, 16(3), 134-137.
Mazzeo, Robert S. “Physiological responses to exercise at altitude.” Sports Medicine 38.1 (2008): 1-8.
Jackson, Catherine G. Ratzin, and Brian J. Sharkey. “Altitude, training and human performance.” Sports Medicine 6.5 (1988): 279-284.