Working in the heat as we know is a tough job – but evidence shows that trained subjects, working in heat of about 40 degrees with 10% relative humidity, and at about 60% of maximal capacity for 10 days increased their overall performance after several days, and had much increased function in general.
What is very interesting is that if this became humid heat then performance dropped rapidly – every subjects’ function drops with maximal performance much earlier (7 minutes). In all cases, performance dropped when the internal body temperature reached 40.1-40.2 degrees.
This does not work if the subjects are untrained – they show much earlier fatigue and inability to perform at lower temperatures – so those who are fitter, inversely are able to perform for longer.
To put this in perspective, experienced and fit shearers are going to be able to perform for longer in higher dry heat than unfit shearers, as long as they keep cool – (tips as discussed previously!) If you are working in moderate humidity - keep doing what you are doing. If you are working in higher humidity where you are likely to be losing less heat, work harder at keeping yourself cool to look after your body and keep your performance up.