ATHLETIC HEAT STRESS RESEARCH
Regional heat safety thresholds for athletics in the contiguous United States
Exertional heat illnesses affect thousands of athletes each year across the United States (U.S.). Heat safety guidelines such as those developed by the American College of Sports Medicine (ACSM) are widely used to direct activities based on environmental conditions but rely on a uniform set of heat safety categories. Due to geographic variations in heat exposure and acclimatization, however, lower heat safety thresholds may be needed in areas with cooler climates. Our study addresses this shortcoming by developing regional guidelines for athletic activity that use relative thresholds of a commonly used heat metric -- the wet bulb globe temperature (WBGT). We employed a unique WBGT climatology for the contiguous U.S. to determine locally extreme WBGTs, defined as the 90th percentile warm season daily maximum value, for 217 stations. Three heat safety regions were identified based on local extremes: Category 3 (WBGTs ≥ 32.3 °C), Category 2 (30.1–32.2 °C), and Category 1 (≤30 °C). Geographically, Category 3 encompasses much of the southeastern quadrant of the U.S. along with portions of the Southwest, and the Central Valley of California; Category 2 areas extend in an arc from the interior Northwest through Nevada and portions of the Midwest, Ohio Valley, and Northeast; and Category 1 locations include the Pacific Coast, New England, and the northern tier of the country. Associated regional activity guidelines based on those developed by the ACSM and the Georgia High School Association (GHSA) were developed for each heat safety region.
Effect of WBGT Index Measurement Location on Heat Stress Category Classification
Differences in WBGT index along 23 km of the Boston Marathon race route can be small enough to warrant single measurements. However, significant misclassification of flag categories occurred using WBGT estimates for meteorological stations; thus, local measurements are preferred. If the relation between station WBGT forecasts and the race sites can be established, the forecast WBGT values could be corrected to give advanced warning of approximate flag conditions. Similar work is proposed for other venues to improve heat stress monitoring.
The Heat Strain of Various Athletic Surfaces: A Comparison Between Observed and Modeled Wet-Bulb Globe Temperatures
The National Athletic Trainers’ Association recom- mends using onsite wet-bulb globe temperature (WBGT) measurement to determine whether to modify or cancel physical activity. However, not all practitioners do so and instead they may rely on the National Weather Service (NWS) to monitor weather conditions.
Roundtable on Preseason Heat Safety in Secondary School Athletics: Environmental Monitoring During Activities in the Heat
To develop best-practice recommendations us- ing thermal indices to determine work-to-rest ratios and facilitate further implementation of environmental monitoring for heat safety in secondary school athletics in the United States.
The Effects of Continuous Hot Weather Training on Risk of Exertional Heat Illness
Our results provide evidence for a cumulative effect of previous day’s heat exposure on EHI risk in these Marine Corps recruits. A simple index for use in predicting EHI risk is proposed that includes the dry-bulb temperature and the relative humidity.
Evaluating Heat Risk: Comparing On‐Site WBGT Measurements Versus Smartphone Application Estimates
Our study compared WBGT values determined by an OS device and those obtained from a PA from over 1,000 paired observations, collected from locations with different surface types and in different climate regions from across the U.S. We found that PA measurements yielded WBGTs that on average were about 1°C lower than those reported by the OS sensors, although discrepancies of 2–3°C were found at hotter WBGTs. Also, the PA tended to underestimate the need for activity modification compared OS devices, particularly in hotter conditions, indicating potential safety concerns for athletes and other active populations relying solely on PA WBGT estimates. Considering this, further validation of the PA is needed before it is adopted in place of OS measurements.