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A pro-athlete recently complained to me that she seemed hungrier while training at a submaximal effort outdoors. She asked, “Do you burn more calories in the colder temperatures?”

Temperatures 0-degrees CELSIUS or lower can increase your caloric need if it is cold enough to elicit the shivering response. Caloric needs are increased due to the increase work of thermogenesis, the body’s temperature regulation. Shivering can increase metabolic heat production 2-5 times above resting. (1) While it is possible to exercise in the cold without the shiver response due to adequate clothing, warm up, fitness level and cold acclimatization, the type of fuel you burn is affected by the temperature. Training at submaximal levels and at temps below 0-degrees Celsius (32-degrees Fahrenheit) relies more on carbohydrate burning than on fat for fuel, at optimal ambient temperatures carbohydrates and fat are burned nearly equally. (2)

Fluid needs are increased due to increased ventilation and low humidity leads to greater respiratory water loss. There is also a reduced thirst response due to the decrease perception of work secondary to low sweat rate. A sport drink will improve fluid retention, fluid balance, and decreased urine output as compared to plain water. It will also provide carbohydrate calories.(1)

The winter months are a time for many of us to maintain or improve our fitness base or aerobic endurance. While training at an aerobic level or submaximal effort (VO2max ~65%) at temperatures below 0-degrees Celsius requires additional considerations as far as proper clothing (wear a hat), equipment, and safety it also has nutritional concerns: make healthy carbohydrate choices and be sure to take adequate fluids.

Kristin McCowan, MS
Kristin.mccowan@simmons.edu

1. Meyer, NL and Parker-Simmons, In Preparation for Torino 2006: Dietary Needs of Winter Sport Athletes, SCAN’S Pulse, Winter 2006, Vol. 25, No. 1

2. Layden, J, Patterson, M and Nimmo, M, Effects of reduced ambient temperature onfat utilization during submaximal exercise, Med & Sci in Sports and Exercise, 34 no 5 May 2002