During the coldest months of the year, we set our new years resolutions, and we put them in practice because 'summer bodies are made in winter' or more serious, our summer basic fitness must be maintained or build in winter. We all know how to dress warm, but what do you have to take into account in terms of foods & drinks when being active in outdoor winter conditions?
What happens when you're physically active when it's cold?
When being physically active in cold conditions, at least 3 important things must be taken into account.
1. You loose more fluids.
Just like during physical activity when it's hot, you loose more fluids than in normal temperatures. The reason for this is that you have more losses via your urine. Are you physically active in dry freezing air, then you are even loosing more fluids through breathing.
2. Your body need to do more effort to control your body temperature.
Your body wants to get rid of the heat caused by being active, but at the same time it has to keep you warm.
3. You will be using 10 - 15% more energy.
During physical activities in cold temperatures compared to physical activities in average temperatures you use more energy. An endurance run of 45 minutes, will not bring you in trouble, but intense physical activities, or an event or competition, can increase energy requirements of your body significant! Certainly during events or competitions which take place on several following days, you will need to cover for the additional energy losses by eating more. Your carbohydrate stores (glycogen store) will be empty faster. Providing your body with carbohydrates when being active for >1,5 hour is therefore essential to maintain the quality of your training and reduce your risk for respiratory infection, which is increased when being physically active in cold weather conditions.
What to eat & drink when being physically active in cold?
Although your body requires more energy and your carbohydrates stores are empty a bit faster, you do not need to eat abnormal amounts of rice, pasta or pancakes the day before your training, event or competition.
The most important thing you have to pay attention to is to start completing your carbohydrate and fluid stores in time. Especially the last part can be tough sometime, because in cold conditions, your will not be noticing you are dehydrating. You'll realize less that you are losing fluids by sweating and in general you will not feel like drinking cold drinks so much.
A tip here is to use thermo-bins, in which you can keep hot drinks warm for several hours or at least lukewarm. This will stimulate you to continue drinking. It can be water or thee, but even heated isotonic sports drink is a perfect choice, because you immediately provide your body with carbohydrates and electrolytes. When being physically active in cold conditions, it is essential to start eating and drinking as of the start an not to wait for 1 hour when the efforts lasts 3 hours for example, because it will be very difficult or even impossible to cover for your losses. During efforts until 2 hours, 30 g carbohydrates is a perfect amount. For efforts between 2 - 3 hours, it should be 60g of carbohydrates per hour. When the effort is longer, you should even go up to 90g of carbohydrates per hour (combination of fructose & glucose). This means that eating and drinking together will be essential.
What should you definitely NOT do?
Of course it is important not to start dehydrated. But water will not be sufficient. Also when it is cold you loose electrolytes, like sodium, potassium, magnesium, etc with your sweat. It is therefore essential not to limit your hydration plan to water only. Water does contain very little electrolytes (minerals) compared to isotonic sport drinks. During endurance activities you loose electrolytes such as potassium, sodium & magnesium which you need to maintain your fluid balance and good muscle contraction.
Then, what should you do?
It is important that your last meal before your physical activity contains sufficient carbohydrates. Next to this, it is important to allow your body to acclimate in order to be prepared for cold conditions when you start an event or competition. Your body will need time to adapt and find it's balance in the cold conditions. Training in cold conditions will allow you to measure your fluids loss under cold conditions, which allows you to adapt your hydration plan & drinking strategy. Measuring fluid loss, can simply be done by using a scale. Weigh yourself before and after a training and measure the amount of fluids you drank during training. Your total fluid loss should preferably not be above 2% of your total body weight. Ensure you train with drinks and foods you will be using during competition and don't be surprised by what the organisation offers. If you have the possibility to take your own products, just make sure they do not freeze. If you're outside for a very long time, keep food like bars close to your body to ensure they do not freeze and you can eat them. After each workout or training in cold conditions it remains important to take a recovery meal or shake rich in carbohydrates including 20 - 25 g of proteins, to allow your body to recover well!
Bron: Vereniging Sportdietetiek Nederland (VSN)