How much variation does task rotation in the computerised office really provide?

![CDATA[Musculoskeletal disorders (MSDs) are associated with information and communication technology (ICT) use among office workers. Current ergonomics research supports variation of muscle activity to mitigate the risk of MSDs. Task rotation is often used to increase variation, but to be effective, consecutive tasks should differ in exposures. Quantification of exposure variability among workers in computerised offices has not been widely researched. This study aimed to determine if there was a difference in variability of upper body muscle activity among office workers when performing tasks using Old ICT(paper-based), New ICT(electronics-based), Combined ICT(paper and electronics-based) and Non ICT tasks. Twenty-four office workers were observed in their natural environments for 10-12 h, while muscle activity of bilateral upper trapezius and the dominant wrist extensors was measured with electromyography (EMG). Tasks and ICT used were documented by an observer and matched to synchronous EMG data. There was no difference in mean amplitudes and variability of trapezius muscle during Old and New ICT tasks. Variation in the right wrist extensors during Old ICT tasks was significantly more than during New ICT. Non ICT tasks had high muscle amplitudes and high variability. Combined ICT tasks had high muscle amplitudes but low variability. Rotating workers only between Old and New ICT tasks at work may not provide sufficient diversity of trapezius muscle activity to reduce the risk of MSDs, but may provide sufficient diversity of the dominant wrist extensors. Alternating paper and electronics-based tasks with Non ICT tasks may increase the effectiveness of task rotation interventions.]]