Researchers Nigel Taylor and Joanne Caldwell conducted research in the harsh heat of northern Australia in a study backed by Meat and Livestock Australia.
The pair said protective equestrian helmets had recently been introduced to parts of the cattle industry, with some pastoral companies requiring musterers to wear them during all riding duties.
However, apart from being uncomfortable, there was anecdotal evidence suggesting their use, particularly models with poor ventilation, may increase the chance of stockmen developing heat illness or experiencing reduced workplace performance.
Taylor and Caldwell, from the university's Human Performance Laboratories, divided the study into three phases.
The first involved an assessment of the working environment of northern Australian cattle stations.
The researchers said it was "abundantly clear" that the working environment on northern Australian cattle stations during mustering seasons is, on average, so hot that individuals are likely to eventually overheat, either through heat production (work) or heat exposure.
"A detailed appreciation of the physiological strain associated with mustering cattle under such conditions, whilst wearing an equestrian helmet, has now been achieved," the authors wrote.
"From the observations of heart rate, and the projected metabolic heat production, it is evident that horseback mustering, under the representative conditions investigated, is a relatively low-intensity activity, interspersed with short periods of high-intensity work."
Core temperature measures of those in the study rarely climbed above values associated with light to moderate physical activity. Thus, stockmen were able to work at rates that meant the progressive rise in core body temperature was kept below levels that might lead to heat illness.
"From sensors located within the helmet and clothing, it was observed that the helmet, though unpleasant to wear, did not appear to behave in a manner that would disadvantage the physiological well-being of stockmen." However, the authors emphasised that the maintenance of an adequate hydration state is critical to the prevention of heat illness and maintaining work performance.
The second phase involved heat penetration trials on four equestrian helmets and a felt akubra hat.
The researchers found a model called the Aussie 21 to have superior physical characteristics, while, from a heat penetration perspective, the Derby and Aussie 21 models appeared to provide very similar thermal protection.
Based on overall performance, the Aussie 21 helmet was chosen for use in the final phase of testing in the laboratory to compare the physiological and cognitive affects of headwear on exercising and heat-stressed individuals.
The Aussie 21 went head to head with the Akubra in a comparison involving eight men in a laboratory that simulated the hot, dry environment of northern Australia. They faced 38deg C heat and 30% relative humidity, and three 500-watt radiant heat lamps were placed 1m overhead to simulate solar loading.
The men were tested in both the Akubra and the equestrian helmet, with half using the helmet first.
In each case they exercised to replicate an average heart rate of a little over 100 beats per minutes, found to be the average when out mustering, but were also exposed short, high-intensity exercise periods. During exercise, core temperatures were slowly driven up over time, satisfying the researchers that they had faithfully replicated work conditions.
The subjects were assessed on core body temperature, skin temperature, heart rate, loss of weight, perceived exertion, heat sensation, discomfort, skin wetness and discomfort, vigilance, reasoning, memory and perceptual reaction time.
It was found that the Aussie 21 equestrian helmet did not adversely affect any of the physiological, psychophysical or cognitive functions evaluated, when compared to wearing the Akubra.
The researchers said that, of the helmets tested, the Aussie 21 equestrian helmet was the most appropriate for use in hot and dry conditions.
"Although not a focus of this study, some design modifications to current helmet brim design could improve protection from solar radiation and sun-burn on the face and neck."