The cumulative physiological effects of consecutive days of simulated occupational heat stress: study protocol for a randomised controlled trial with healthy adults undertaken in Australia.

backgroundFuelled by rising global temperatures, occupational heat stress has become a critical threat to the health and safety of workers. This threat may be particularly great for workers who are required to perform prolonged work in the heat over multiple consecutive days; however, the cumulative physiological impact of these work conditions remains unclear. As such, the primary objective of this study is to determine the effects of three consecutive simulated physically demanding workdays in a hot and humid environment on core temperature (primary outcome), with secondary objectives examining the impact on heart rate, hydration status, physical task performance, and cognitive function.

methodsThe study will involve an open-label exploratory randomised within-subject cross-over experimental trial, lasting 74 h. All trials will be conducted at Deakin University, Australia, in a climate-controlled environmental chamber. Participants will complete three consecutive days of simulated physically demanding work. Participants will be healthy, physically active male and female non-smokers aged 18-40 years, with a body mass index (BMI) < 35 kg·m DISCUSSION: Growing evidence indicates that working in the heat on consecutive days, a common situation for many workers, may lead to a cumulative increase in the physiological strain on the body. This will commensurately increase the risk of heat-related injuries while also increasing susceptibility to a range of health issues. Our findings will inform whether current heat management practices need to be adjusted to consider the impact of repeated heat exposures. Australian New Zealand Clinical Trials Registry,  https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=386410 ; First planned enrolment 15/04/2024.

trial registrationACTRN12623001069640. Registered on 06/10/2023.