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Published online: 10 September 2015
^ Springer International Publishing Switzerland 2015
We have read with great interest the comprehensive review of our colleagues [1] on the 'hot' topic of training and competing in the heat. We agree with the authors that environmental indices should be defined with guidelines rather than universal (fixed) cut-off values across different sporting disciplines. However, we are surprised that they did not highlight one of the main current limitations: the recommendations for various sporting governing bodies (i.e., event organizers and international federations) are still based on the wet-bulb globe temperature (WBGT) index. We believe that this point is paramount for improving heat-related exercising safety guidelines.
The WBGT, originally developed by the US Navy [2], is used world-wide as a screening tool for the assessment of environmental heat stress during industrial, military, occupational, and sport applications, and has been recommended by the International Organization for Standardization (ISO) certification (ISO 7243, ISO/DIS 7933 [3]), American Conference of Governmental Industrial Hygienists (ACGIH, [4]), American College of Sports Medicine (ACSM, [5, 6]), International Olympic Committee [7], and numerous leading sports federations (e.g., Fédération Internationale de Football Association [FIFA], International Association of Athletics Federations [IAAF], International Tennis Federation [ITF] [8, 9]). This empirical index is computed from the reading of the dry-bulb temperature and two derived measures: the natural wet-bulb temperature and the black-globe temperature. Notwithstanding the primary recommendations by ISO and ACGIH-that is, to use WBGT as a preliminary tool, while the predicted heat strain (PHS) approach (ISO 15265 [10]) must be used to investigate more severe heat conditions-many users still utilize only the WBGT index regardless of the severity of the thermal environment. Because ''its origin, and its limitations are apparently being forgotten'' [11], the WBGT is seen as a user-friendly and reliable measure of heat stress. Nearly 60 years after its first formulation, d'Ambrosio Alfano et al. [12] recently critically reviewed the WBGT and clearly demonstrated that it is becoming obsolete. Briefly, the main issue is that the WBGT does not appropriately reflect the severity of the weather/ climate. This is mainly due to the following:
1. The use of nonstandard instrumentations or unreliable calibration procedures.
2. The debate on the assessment of the natural wet-bulb temperature, which is not a thermodynamic parameter...