Uncovering the pattern of physical behaviours among Swedish ambulance personnel: is the type of work shift important?

Previous studies indicate that ambulance personnel have an increased risk of ill health. Shift work and time spent on physical behaviours during work and leisure are factors that could be related to health, however the research is limited. Thus, the aim of this study was to describe patterns of physical behaviours during and after work among Swedish ambulance personnel and to analyse the associations between physical behaviours and different work shifts. In this observational study, the physical behaviours of 63 ambulance personnel were measured over seven days using two accelerometers. Accelerometer data was processed using the MATLAB program Acti4, to identify physical behaviours i.e. sleep, being sedentary, light physical activity (LPA), and moderate to vigorous physical activity (MVPA), during and after work. To determine the association between shift types (independent) and patterns of physical behaviours (dependent), a Multivariate Analysis of Variance was performed on data processed according to compositional data analysis. At work, the highest proportion of both MVPA and being sedentary occurred during day shifts, compared to night and 24-h shifts (MVPA: 7% vs 4% and 5%; sedentary time: 62% vs 44% and 54% respectively). Night and 24-h shifts included 31% and 18% sleep, respectively. During the after-work periods, the highest proportions of MVPA were observed after 24-h shifts (8%). Overall, there was no statistically significant difference in physical behaviours during work and after work for various shift types. However, in a sub-analysis restricted to night and 24-h shifts, a statistically significant association between shift type and composition of physical behaviours during work was observed (ηp2 = 0.42, p < 0.001), with a lower proportion of sleep time relative to awake time during 24-h shifts compared to night shift (ηp2 = 0.34, p < 0.001). In general, ambulance personnel were physically active both during and after work. At the same time, work hours entailed a substantial amount of sedentary time. Shift type was not associated with the pattern of physical behaviours among ambulance personnel. However, during 24-h shift a lower proportion of the time was spent sleeping compared to during night shift. Studies with larger sample sizes are needed to confirm these results.