There are many mysterious and wonderful things about exercising in cold weather. Many cold-loving athletes relish the fact that nothing can stop them from training outside. They seem to say, “I can beat Mother Nature.” They welcome the challenge of finding the perfectly balanced layering system of clothes (not too hot, not too cold, just right!), and they smile at the wind on their face and the “crunch” of snow under their running shoes. Of course, others think walking from car to gym is enough outdoor activity during chilly winter weather!
Wherever you and your clients fall on this spectrum, science favors stepping outside, since cold-weather workouts can deliver unique benefits. However, researchers have also identified a number of concerns and cautions to keep in mind. Here is a summary of the evidence, along with specific ways to ensure safety among special populations, such as people with pre-existing health conditions, children and older adults. Fortunately, with certain precautions, outdoor exercise in the cold can be safe for almost everyone (Fudge 2016; Mayo Clinic 2016).
Benefits of Training in Cold Weather
The benefits of cold-weather training are similar to those of any kind of exercise—with some unique exceptions. Switching to different modalities in winter will automatically increase metabolic load as the body adapts to different movement patterns. Cross-country skiing is a good example. Whether we are skate skiing or doing classic style, we will have a higher metabolic load than if we were running (for example), simply because we’re moving differently.
EXAMPLE ACTIVITY: CROSS-COUNTRY SKIING
Smith & Holmberg (2010) observe that cross-country skiing is one of the most demanding sports because the technique involves both upper and lower body as well as core stabilization, acceleration and deceleration. Lawless (2014) adds that endurance, altitude and variations in intensity (sprints) and distance further increase the demands.
VO2 MAX FOR MALE ATHLETES
(in milliliters per kilogram of body weight per minute)
cross-country Olympic skiers 96
world-class cyclists 75–90
cross-country distance skiers 81–87
cross-country sprint skiers 75–81
elite marathon runners 70–85
elite swimmers 66–80
Sources: Tønnessen et al. 2015; Joyner, Ruiz & Lucia 2011; Jorgić et al. 2011; Peiffer et al. 2008.
Female athletes are usually 10 ml/kg/min below their male counterparts. For example, women cross-country distance skiers have a VO2max of 68–77, and sprint skiers have a VO2max of 64–73. Paula Radcliffe, who set the women’s marathon world record in 1992, had a VO2max of 65–75 ml/kg/min (McClusky 2015).
OTHER EXCELLENT OPTIONS FOR COLD-WEATHER EXERCISE
There are many wintertime activities to help us get our metabolic load on. A popular new sport is fat-tire mountain biking (“fat biking”). The bikes used are similar to regular mountain bikes except that the thicker tires stay on top of the snow. Most people ride in the city, on designated trails or (where allowed) on cross-country ski trails.
Snow shoeing has been around for decades, but the sport is being reinvented with lighter snow shoes and dedicated trails.
Alpine skiing and sliding sports (such as snowboarding, half pipe and slopestyle) do not have the higher metabolic load that other winter sports do; however, they can get participants into serious concentric and eccentric muscle contractions.
According to the Compendium of Physical Activities, the following popular winter sports have these metabolic equivalents of task (ASU 2011):
cross-country skiing, 5.0–7.9 mph, vigorous effort 12.5
snow shoeing, vigorous effort 10.0
cross-country skiing, moderate speed and effort 9.0
ice skating, 9 mph or faster 9.0
downhill skiing, vigorous effort 8.0
ice skating, general 7.0
downhill skiing or snowboarding, moderate effort 5.3
snow shoveling, by hand, moderate effort 5.3
Reminder: One MET equals the average resting metabolic rate for adults.
SOME FACTS ABOUT METABOLISM IN COLD WEATHER
There is a misconception about energy metabolism during cold-weather training. Many people think that when it’s cold we have a higher metabolic load because the body must work harder to exercise and to keep warm. That is not necessarily the case unless, perhaps, a participant is not wearing adequate layers for the temperatures and wind chill.
Molkov & Zaretsky (2016) note that 80% of energy generated in the muscles during exercise is wasted (i.e., dissipated). As the body heats up, the thermoregulatory system may halt or suppress metabolic heat production; therefore, exercising in a cold environment merely trades one type of thermogenesis for another as the body seeks homeostasis.
Other researchers have examined whether fat metabolism increases at colder temperatures. Gagnon et al. (2013) conducted a small study to compare energy substrate use during walking and running in temperatures of 32 degrees Fahrenheit versus 71.6 F (0 degrees Celsius/22 C). Participants were 10 lightly clothed males who walked or ran for 60 minutes at 50% and 70% of VO2max. In the cold, there was a higher reliance on fat as the predominant substrate, as had been seen previously in cycling studies.
Further, exercise VO2 is generally higher in the cold, but the difference between warm and cold environments decreases as workload increases (Doubt 1991).
Special Precautions for Special Populations
We’ve reviewed how cold-weather athletes fare while training in cold weather and how it affects their physiology, but what about clients with special considerations? These clients must take special precautions if they are to train safely in colder temperatures. Of course, many of these people will be the same clients who need accommodations in a gym setting or more temperate climates.
Below are some basic concerns for a few of the more common special populations. Some of these concerns may surprise you. For a client in any of these groups, it is wise to be in close contact with the participant’s healthcare team to ensure the safest and most successful outcomes.
PEOPLE WITH DIABETES
Kenny, Sigal & McGinn (2016) conducted a review of the literature investigating diabetes and exposure to extreme temperatures with reference to core temperature regulation, cardiovascular adjustments and glycemic control. The research revealed that those with diabetes can be more vulnerable to injuries and illnesses related to cold temperatures. Injury risk can be reduced by maintaining glycemic control, maintaining or increasing cardiovascular fitness, and preventing diabetes-related complications.
Diabetes can reduce circulation to the hands, feet and other extremities (nose, ears, face), which can increase the risk of frostbite. Those who have diabetic neuropathy (nerve damage due to diabetes) are particularly susceptible because their ability to feel temperature changes is blunted. The ability to keep core temperature stable may also be compromised in people with diabetes. Thus, dressing appropriately is key.
Diabetes medicines and supplies are sensitive to the cold, as well. Most blood glucose meters work best above 50 F, and insulin and some other diabetes medicines should not be allowed to freeze (CHOP 2016; Neithercott 2012; JDC 2018). Tucking items inside clothing or storing them in an insulated pack may help them stay warm enough.
Clients who check blood sugar should tell the fitness professional how often they will need to do this during cold-weather exercise (CHOP 2016). Keeping hands warm will make it easier to get a drop of blood from a finger for use in a meter (Neithercott 2012).
PEOPLE WITH HEART DISEASE
Low temperatures, biological factors (including age) and air pollution may contribute to the higher risk of cardiovascular diseases that has been observed in research (the exact mechanism is not known). Clients should certainly be aware of the risk, but experts still recommend engaging in regular physical activity, along with dressing warmly and following a healthy diet (Fares 2013).
Much of the research literature on heart disease and cold temperatures has focused on heart attacks during exposure to cold or while shoveling snow, not during exercise programs. For people with CVD, the increased risk of cold-weather workouts may stem from a combination of high altitude, freezing temperature and inadequate conditioning (e.g., weekend warriors on the slopes). Research has shown that the risk of heart attack for winter tourists was highest during the first 2 days of their trip (THI n.d.). The recommendation is to give the body a few days to acclimate to environmental changes before engaging in high-exertion activities.
Breathing in cold air sometimes causes angina pectoris (chest pain or discomfort) in people with coronary artery disease. Covering the mouth with a scarf or mask during time outdoors may help to prevent this. Many people with CVD may be able to exercise safely outdoors in the winter after consulting with their doctor. Even so, fitness professionals must be aware of the warning signs of heart attack (and stroke) and should err on the side of caution (AHA 2015; THI n.d.).
PEOPLE WITH ASTHMA
According to the American Academy of Allergy, Asthma and Immunology (2018), cold, dry air can trigger exercise-induced bronchoconstriction (EIB), with symptoms presenting in the first 5–20 minutes, even among people who do not normally have asthma. Wheezing, shortness of breath, tightness in the chest and coughing can be signs of EIB. Cold weather can make symptoms worse for people with asthma (Healthline 2018). In addition, air pollution and exercising in cold, dry air may cause airway hyperresponsiveness or even injury if steps are not taken to mitigate the effects.
Rundell and Sue-Chu (2013) found a higher frequency of asthma among athletes who competed and trained outside in cold air. Kennedy and Faulhaber (2018) recommend reducing exercise intensity and covering the nose and mouth with a scarf to humidify the air. Schachter, Lach & Lee (1981) found that a cold-weather mask helped protect exercisers with asthma. Taking time to warm up and cool down can also lessen the symptoms of EIB, but rescue medications and other measures can be taken, with a doctor’s guidance, if necessary (AAAAI 2018).
Because kids have a higher ratio of surface area to body mass, their rate of body heat loss is faster than that of adults (AAP 2018). When children exercise in the cold, the surface-area-to-body-mass ratio is compensated for by improved peripheral vasoconstriction and metabolic heat production. Peripheral vasoconstriction can be a risk factor for chilblains, frostnip or frostbite. Cold air may also cause EIB (Bar-Or 1994). Because of these factors, youth athletes must wear properly layered clothing, including a scarf, mask or other covering of the mouth and nose.
The National Institute of Aging (a division of the National Institutes of Health) warns that older adults face a twofold concern regarding temperature: First, they can lose body heat faster than younger people. Second, owing to physiological changes, they may be less able to sense such temperature changes.
For a variety of reasons, chronic medical conditions can exacerbate these concerns. Some conditions, like thyroid problems and diabetes, cause challenges with thermoregulation and diminished blood flow, both of which can make it difficult to stay warm. Conditions that affect dexterity or cognitive function (e.g., arthritis, Parkinson’s disease, and memory loss or dementia) can make it more difficult to add layers of clothing or use good judgment regarding when to stay indoors. Further, ingesting alcoholic beverages or certain medications, including cold medicines, can affect thermoregulation.
With so many factors in play, the NIA suggests that older adults talk with their healthcare provider to ask if they are at greater risk for hypothermia and what guidelines they should follow (NIA 2018). Fitness professionals working with this population would benefit from addressing these questions during a preparticipation health screening or, with existing clients, prior to adding cold-weather workouts to current programming.
Despite these concerns regarding outdoor workouts, the NIA reports that physical activity is extremely beneficial to older adults in terms of functionality, independence and self-control, disease prevention and management, balance and fall prevention, increased energy, better sleep, improved mood, and reduced symptoms of depression and stress (Go4Life n.d.).
A Fun Way to Vary Fitness Programming
Generally speaking, exercising in cold weather is safe and fun. Even if a person has a pre-existing health condition, specific precautions can be followed to make the exercise session safer and more beneficial. With proper preparation and a positive attitude, cold-weather exercise can be one of best experiences for you and your clients. It’s worth the extra effort, but the only way to know that for yourself is to layer up and open the door.
AAAAI (American Academy of Allergy, Asthma and Immunology). 2018. Asthma and winter sports. Accessed Nov. 2, 2018: aaaai.org/conditions-and-treatments/library/asthma-library/asthma-winter-sports.
AAD (American Academy of Dermatology). 2018. Frostbite: Prevention and treatment. Accessed Nov. 2, 2018: aad.org/public/skin-hair-nails/injured-skin/frostbite.
AAP (American Academy of Pediatrics). 2018. Extreme temperatures: Heat and cold. Accessed Nov. 2, 2018: aap.org/en-us/advocacy-and-policy/aap-health-initiatives/Children-and-Disasters/Pages/Extreme-Temperatures-Heat-and-Cold.aspx.
AHA (American Heart Association). 2015. Cold weather and cardiovascular disease. Accessed Nov. 2, 2018: heart.org/en/health-topics/consumer-healthcare/cold-weather-and-cardiovascular-disease.
ASU (Arizona State University). 2011. 19–Winter Activities. Compendium of Physical Activities. Accessed Sep. 26, 2018: sites.google.com/site/compendiumofphysicalactivities/Activity-Categories/winter-activtities.
Bar-Or, O. 1994. Children’s responses to exercise in cold climates: Health implications. Sports Science Exchange #51, 7 (4).
CHOP (Children’s Hospital of Philadelphia). 2016. Hot tips for managing diabetes in cold weather. Accessed Nov. 1, 2018: chop.edu/news/hot-tips-managing-diabetes-cold-weather.
Doubt, T.J. 1991. Physiology of exercise in the cold. Sports Medicine, 11 (6), 367–81.
Fares, A. 2013. Winter hypertension: Potential mechanisms. International Journal of Health Sciences, 7 (2), 210–19.
Fudge, J. 2016. Preventing and managing hypothermia and frostbite injury. Sports Health, 8 (2), 133–39.
Gagnon, D.D., et al. 2013. Cold exposure enhances fat utilization but not non-esterified fatty acids, glycerol or catecholamines availability during submaximal walking and running. Frontiers in Physiology, 4 (99).
Go4Life. n.d. How exercise can help you. Accessed Nov. 1, 2018: go4life.nia.nih.gov/how-exercise-can-help-you/?hilite=%27depression%27.
Healthline. 2018. How to treat asthma triggered by cold weather. Accessed Nov. 2, 2018: healthline.com/health/asthma/cold-induced-asthma#connection-between-cold-weather-and-asthma.
JDC (Joslin Diabetes Center). 2018. Warming up to winter exercise. Accessed Nov. 1, 2018: joslin.org/info/Warming_Up_to_Winter_Exercise.html.
Jorgi´c, B., et al. 2011. Importance of maximal oxygen consumption during swimming. Physical Education and Sport, 9 (2), 183–91.
Joyner, M.J., Ruiz, J.R., & Lucia, A. 2011. The two-hour marathon: Who and when? Journal of Applied Physiology, 110 (1), 275–77.
Kennedy, M.D., & Faulhaber, M. 2018. Respiratory function and symptoms post cold air exercise in female high and low ventilation sport athletes. Allergy, Asthma & Immunology Research, 10 (1), 43–51.
Kenny, G.P., Sigal, R.J., & McGinn, R. 2016. Body temperature regulation in diabetes. Temperature: Medical Physiology and Beyond, 3 (1), 119–145.
Lawless, C.E. 2014. Sports cardiology of cross country skiing: Sochi postcard. Accessed Nov. 1, 2018: acc.org/latest-in-cardiology/articles/2014/07/18/12/57/sports-cardiology-of-cross-country-skiing-sochi-postcard.
Mayo Clinic. 2016. Winter fitness: Safety tips for exercising outdoors. Accessed Nov. 2, 2018: mayoclinic.org/healthy-lifestyle/fitness/in-depth/fitness/art-20045626.
Mayo Clinic. 2018. Frostbite. Accessed Nov. 2, 2018: mayoclinic.org/diseases-conditions/frostbite/symptoms-causes/syc-20372656.
McClusky, M. 2015. Faster, Higher, Stronger: The New Science of Creating Superathletes, and How You Can Train Like Them. New York: Plume.
Molkov, Y.I., & Zaretsky, D.V. 2016. Why is it easier to run in the cold? Temperature: Medical Physiology and Beyond, 3 (4), 509–11.
Neithercott, T. 2012. Snowboarder Sean Busby shreds tough slopes. Diabetes Forecast Online. Accessed Nov. 1, 2018: diabetesforecast.org/2012/feb/snowboarder-sean-busby-shreds-tough-slopes.html.
NIA (National Institute on Aging). 2018. Hypothermia and older adults. Accessed Nov. 1, 2018; nia.nih.gov/news/hypothermia-and-older-adults.
NWS (National Weather Service). n.d. Active alerts. Accessed Nov. 2, 2018: weather.gov/alerts.
Oksa, J. 2002. Neuromuscular performance limitations in cold. International Journal of Circumpolar Health, 61 (2), 154–62.
Peiffer, J.J., et al. 2008. Physiological characteristics of masters-level cyclists. The Journal of Strength and Conditioning Research, 22 (5), 1434–40.
Rundell, K.W., & Sue-Chu M. 2013. Air quality and exercise-induced bronchoconstriction in elite athletes. Immunology and Allergy Clinics of North America, 33 (3), 409–21.
Schachter, E.N., Lach E., & Lee, M. 1981. The protective effect of a cold weather mask on exercised-induced asthma. Annals of Allergy, 46 (1), 12–16.
Smith, G.A., & Holmberg, H-C. 2010. Nordic skiing biomechanics and physiology. Conference Paper: The 28th International Symposium of Biomechanics in Sports, Marquette, MI. Accessed Nov. 1, 2018: researchgate.net/publication/259647166_Nordic_skiing_biomechanics_and_physiology.
THI (Texas Heart Institute). n.d. Cold-weather exercise. Accessed Nov. 2, 2018: texasheart.org/heart-health/heart-information-center/topics/cold-weather-exercise/.
Tønnessen, E., et al. 2015. Maximal aerobic capacity in the winter-Olympics endurance disciplines: Olympic-medal benchmarks for the time period 1990–2013. International Journal of Physiology Performance, 10 (7), 835–39.