Fatigue has been identified as a significant contributor to workplace accident rates. However, risk minimisation is a process largely based on self-reporting methodologies, which are not suitable for fatigue identification in high risk industries. Wearable technology which is capable of collecting physiological data such as step and heart rates as an individual performs workplace tasks has been proposed as a possible solution. Such devices are minimally intrusive to the individual and so can be used throughout the working day. Much is promised by the providers of such technology, but it is unclear how suitable it is for in-situ measurements in real-world work scenarios. To investigate this, we performed a series of studies designed to capture physiological and psychological data under differing (physical and mental) loading types with the intention of finding out how suitable such equipment is. Using reaction time (simple and choice) as a measure of performance we found similar correlations exist between loading duration and our measured indicators as those found in large-scale laboratory studies using state of the art equipment. Our results suggest that commercially available activity monitors are capable of collecting meaningful data in workplaces and are, therefore, worth investigating further for this purpose.