Immersion of the forearms is a cooling strategy utilised predominantly within firefighting and military settings. In conjunction with Dr Anthony Walker of ACT Fire and Rescue Service, we reviewed the cooling rates of forearm immersion, publishing our results in 2015. At that point, the forearm immersion cooling rates were deemed unsuitable for occupational settings with core temperature only decreasing 0.1-0.5ºC per 10 minutes of cooling. These rates were similar and in some cases slower than without cooling. In 2016, a study by Yeargin and colleagues reported a cooling rate of 1ºC per 10 minutes by immersion of forearms in 5ºC water. Such a cooling rate was substantially higher than the other studies as this was the first study to trial water of less than 10ºC. So, is forearm immersion a viable workplace heat stress control?
In short the answer is no, unless 5ºC water is utilised for a minimum of ~10 minutes. In that time, workers may report numbness and discomfort of the forearms and experience diminished manual dexterity upon return to work scene. The logistics of this method are a barrier to implementation, an issue that has been amplified due to infection control/COVID-19 protocols. COVID-19 aside, provision of 5ºC water in ample quantities for cooling multiple workers is a challenge. The use of ice cold towels to cool the forearms is a potential alternative to immersion that requires substantially less water, and fewer resources. A recently published study by Adams and colleagues reported cooling rates conferred by wrapping the forearms in cold towels (1-3ºC) rotated every three minutes. As represented by the figure below, the mean cooling rate of ~0.22ºC per 10 minutes was slower than without cooling, excluding towels as a surrogate of 5ºC water immersion.
In summary, forearm immersion poses several logistical issues and is not worth pursuing as a workplace heat stress hazard control unless cold water and the means for achieve immersion are readily available proximal to the worksite, and cold hands/arms are not detrimental to work performance.
Adams WM, Morris EC, Walton SL, Karras EM (2021). Comparing the Cooling Rates of Rotating Forearm Ice Towels and Passive Rest Following Exercise-Induced Hyperthermia. Athletic Training & Sports Health Care. 1:e1-6.
Brearley M, Walker A (2015). Water immersion for post incident cooling of firefighters; a review of practical fire ground cooling modalities. Extreme Physiology and Medicine. 4:15
Yeargin S, McKenzie AL, Eberman LE, Kingsley JD, Dziedzicki DJ, Yoder P (2016). Physiological and Perceived Effects of Forearm or Head Cooling During Simulated Firefighting Activity and Rehabilitation. Journal of Athletic Training. 51(11):927-935.