Easter is here – have you tested your equipment and brought enough food for your trip to the mountains?
Testing oxygen consumption during moderate and intense digging in the snow.
Resting energy consumption increases in the cold climate. When working outdoors in the cold, factors such as temperature, wind chill, food and water intake, clothes and gear for protection need to be considered. Preparing in advance in case of stormy weather is essential for outdoor activities like breaking camp, or digging snow shelters. It is critical to bring the necessary equipment if you plan to, or by accident need to spend one or more nights outdoors.
Not only is equipment such as tent, storm shelter bag, sleeping bag and padding, shuffle, snow saw and cooking equipment necessary, you also need to check the quality and workability of your gear beforehand. Raise and dismantle your tent at home, check the status of your sleeping bag and “test-burn” your primus! These are some of the equipment tests for preparing for your mountain trip.
Making an emergency shelter, such as a snow cave, by digging and sawing snow and moving blocks of snow is both time consuming, and requires great energy consumption. During the “Enjoy the Cold” physiology class at Ny Ålesund, Svalbard, maximal oxygen consumption and oxygen consumption during snow sawing and digging was measured in participants. In one participant with a maximal oxygen consumption of 49.5 ml∙kg-1∙min-1 (3.65 L∙min-1) the oxygen consumption during snow sawing and digging were at a steady state value of 32 ml∙kg-1∙min-1 (2.35 L∙min-1) while maximal values during intense digging was a high as 42 ml∙kg-1∙min-1 corresponding to 65% and 85% of maximal oxygen consumption (see the picture above).
This corresponds to an energy consumption of 11.8 Kcal∙min-1 and 15.9 Kcal∙min-1 making the 30 minute and 1 hour energy consumption as high as 354/708 kcal and 477/954 kcal at moderate and intense digging intensity respectively. Depending on snow conditions, the size of the snow cave and number of people digging, a snow cave could be completed in 2-4 hours. Based on the data recorded from our test person this indicates that you will have to eat up to 2832 kcal digging at moderate intensity for 4 hours while intense digging during the same time span would require up to 3816kcal.
Testing skin temperature with thermo-loggers
These are not absolute values and may vary vastly due to above-mentioned factors, but the data clearly demonstrates that digging a snow cave is energy demanding. When planning your meals during your trip you must remember that various nutrients provide different amount of energy per gram (carbohydrates: 1g=4kcal, protein 1g=4kcal and fat: 1g=9kcal). This is important to keep in mind due to the weight of the food, duration and intensity level of the work. In addition, and extremely important, do not forget to drink plenty of water (preferably warm) in cold environments.
Monitoring skin temperature with infrared camera
The course “Enjoy the Cold” reminds participants of the importance of proper clothing. While digging a snow cave, you should strive to dig while standing, instead of lying in the snow, and try to avoid overheating or freezing by wearing proper clothing. If you are too warm you will increase sweat production, your clothes will become wet and you will start freezing when the activity level goes down. To test if the participants dressed correctly we monitored their skin temperature a 5 different places using Veriteq thermo-loggers (picture 2) in addition to FLIR infrared cameras (picture 3). Additionally, a much easier estimate is weighing your clothes on a scale before and after a session.
If you would like to learn more about cold physiology and how to behave and dress in an outdoor/working environment you can join the next course in Ny–Ålesund, 7-13 March 2013. Meanwhile we wish you safe travels during your holiday in the mountains!
Written by Trine Karlsen and Svein Erik Gaustad, both Post doctors at CERG.
Cardiac Exercise Research Group 