Table 1.
Wet-bulb globe temperature (WBGT) levels for modification or cancelation of workouts or competition for healthy adults [15]
| WBGT | Continuous activity and competition | Training and non-continuous activity | ||
|---|---|---|---|---|
| °F | °C | Non-acclimatized, unfit, high-risk individualsa | Acclimatized, fit, low-risk individualsa,b | |
| ≤ 50.0 | ≤ 10.0 | Generally safe; EHS can occur associated with individual factors | Normal activity | Normal activity |
| 50.1–65.0 | 10.1–18.3 | Generally safe; EHS can occur | Normal activity | Normal activity |
| 65.1–72.0 | 18.4–22.2 | Risk of EHS and heat illness begins to rise; high-risk individuals should be monitored or not compete | Increase the rest: work ratio. Monitor fluid intake. | Normal activity |
| 72.1–78.0 | 22.3–25.6 | Risk for all competitors is increased | Increase the rest: work ratio; decrease total duration of activity. | Normal activity monitor fluid intake. |
| 78.1–82.0 | 25.7–27.8 | Risk for unfit, non-acclimatized individuals is high | Increase the rest to work ratio; decrease intensity and total duration of activity. | Normal activity monitor fluid intake. |
| 82.1–86.0 | 27.9–30.0 | Cancel level for EHS risk | Increase the rest to work ratio to 1:1, decrease intensity and total duration of activity. Limit intense exercise. Watch at-risk individuals carefully. | Plan intense or prolonged exercise with discretionc, watch at-risk individuals carefully |
| 86.1–90.0 | 30.1–32.2 | Cancel or stop practice and competition. | Limit intense exercisec and total daily exposure to heat and humidity; watch for early signs and symptoms | |
| ≥90.1 | ≥32.3 | Cancel exercise. | Cancel exercise uncompensable heat stressd exists for all athletesc | |
EHS exertional heat stroke, WBGT wet-bulb globe temperature
aWhile wearing shorts, T-shirt, sock, and sneakers
bAcclimatized to training in the heat at least 3 week
cDifferences of local climate and individual heat acclimatization status may allow activity at higher levels than outlined in the table, but athletes and coaches should consult with sports medicine staff and should be cautions when exceeding these limits
dInternal heat production exceeds heat loss and core body temperature rises continuously, without a plateau