Prevention of Cold Injuries during Exercise

Abstract

SUMMARY It is the position of the American College of Sports Medicine that exercise can be performed safely in most cold-weather environments without incurring cold-weather injuries. The key to prevention is use of a comprehensive risk management strategy that: a) identifies/assesses the cold hazard; b) identifies/assesses contributing factors for cold-weather injuries; c) develops controls to mitigate cold stress/strain; d) implements controls into formal plans; and e) utilizes administrative oversight to ensure controls are enforced or modified. The American College of Sports Medicine recommends that: 1) coaches/athletes/medical personnel know the signs/symptoms and risk factors for hypothermia, frostbite, and nonfreezing cold injuries, identify individuals susceptible to cold injuries, and have the latest up-to-date information about current and future weather conditions before conducting training sessions or competitions; 2) cold-weather clothing be chosen based on each individual's requirements and that standardized clothing ensembles not be mandated for entire groups; 3) the wind-chill temperature index be used to estimate the relative risk of frostbite and that heightened surveillance of exercisers be used at wind-chill temperatures below −27°C (−18°F); and 4) individuals with asthma and cardiovascular disease can exercise in cold environments, but should be monitored closely. INTRODUCTION People exercise and work in many cold-weather environments (low temperature, high winds, low solar radiation, rain/water exposure). For the most part, cold-weather is not a barrier to performing physical activity. Successful and safe exploration to the North and South Poles, and swimming for hours across the English Channel are clearly indicative that human beings can perform in extreme cold. Many factors, including the environment, clothing, anthropometric factors, health status, age, and exercise intensity, interact to determine if exercising in the cold elicits additional physiological strain and injury risk beyond that associated with the same exercise done under temperate conditions. In many cases, exercise in the cold does not increase strain or injury risk, and David Bass, the noted environmental physiologist, once stated that "man in the cold is not necessarily a cold man." (6). However, there are scenarios (immersion, rain, low ambient temperature with wind) where whole-body or local thermal balance cannot be maintained during exercise-cold stress, contributing to cold-weather injuries and diminished exercise capability and performance. Furthermore, exercise-cold stress can increase the risk of morbidity and mortality in certain susceptible populations (45,84,98). This position statement provides guidance to enable people exercising in the cold to avoid cold-weather injuries. Objectives of the Position Stand are to: 1) define the most common cold-weather injuries expected during exercise-cold stress, 2) present factors that increase the risk of sustaining a cold-weather injury, and 3) provide appropriate guidance to prevent or lower susceptibility to cold-weather injuries. Cold-weather outcomes or cold-related injuries include hypothermia, frostbite, cold urticaria, and nonfreezing cold injuries, and also outcomes secondary to being in the cold including cold-induced asthma and acute cardiovascular events such as myocardial infarction. Cold stress refers to environmental and/or personal conditions that tend to remove body heat and decrease body temperature. Cold strain refers to physiological and/or psychological consequences of cold stress. This position statement is applicable to all athletic activities in the cold including those that are short-term (jogging, running, skiing, biathlon, speed skating, outdoor hockey), medium term (adventure racing, triathlon, marathons, long-distance swimming), and long-term (mountaineering and expeditions). EVIDENCE CLASSIFICATION This Position Stand presents an evidence-based review based on a criteria scale proposed by the American Academy of Family Physicians. This scale is called the Strength of Recommendation Taxonomy (SORT). Table 1 presents the SORT. Recommendations are given a grade of A, B, or C based on patient- or disease-oriented outcomes. The SORT can be accessed from the American Family Physician Web site, www.aafp.org. The reader should be cognizant that classifying evidence using this taxonomy heavily emphasizes outcome-based treatments. However, outcome-based research on medical effects of exposure to cold is limited by the ethical constraints that preclude the design of studies that use frostbite or severe hypothermia as an outcome in human volunteer subjects.TABLE 1: Strength of recommendation taxonomy.PHYSIOLOGICAL RESPONSES TO COLD Acute cold exposure. Humans exhibit peripheral vasoconstriction upon cold exposure. The resulting decrease in peripheral blood flow reduces convective heat transfer between the body's core and shell (skin, subcutaneous fa