Firefighter clothing is known to restrict movement and increase the risk of musculoskeletal injury. The aim of this study was to investigate differences between clothing variations and firefighter mobility. Data were collected from eight firefighters using a randomized counterbalanced, repeated measures, design. Three different clothing variants (V1-V3) in addition to current station wear (S) were trialed. Combinations of S and V1 (SV1) and V2 (SV2) were also trialed. Outcome measures included: standing reach height; the Functional Movement Screen [FMS]; vertical jump; a visual analogue scale [VAS] for the FMS, vertical jump, step ups and crawl; and a mannequin sketch to mark areas of discomfort. V3 was preferred over S in all tasks and performed better both objectively (FMS and vertical jump) and subjectively (VAS scores). While V1 was typically associated with poorer performance, the impacts of V1 and V2 when compared to each other and S varied depending on the tasks performed. This variation was greater when V1 or V2 were worn with S (SV1 and SV2). Areas of discomfort across all variations was the knees, followed by the thighs. Clothing that has the least impact on, or improves, mobility (especially around the lower limbs) may help reduce firefighter injury and limit subjective discomfort.Safety 2019, 5, 78 2 of 18 while stepping over it. Conversely, in wildland firefighters, a 15 kg pack was found to significantly increase their time to negotiate escape routes during a wilderness fire forced evacuation [14].In addition to the load weights, the nature of the equipment and clothing worn by firefighters is thought to impact both their performance and injury risk. The bulkiness and rigidity of the PPE clothing worn by firefighters, for example, is known to reduce their mobility and has been considered to increase the risk of injury through increasing the potential for a slip, trip or fall [2,3,15]. SCBA and boot sizes (heights), in particular, have been associated with reducing mobility, increasing physical stress, and increasing the risk of slips, trips, and falls (3). As such, it is not surprising that the wearing of SCBA and boots are major contributors to fireground musculoskeletal injuries [3].Given that slips, trips, and falls are a common mechanism for firefighter injuries to occur, and that the PPE worn by firefighters can increase their risk of a slip, trip, or fall, research investigating the impacts of different firefighter PPE clothing variations on their mobility may be of value and provide a means of optimising clothing design and development in order to mitigate these injuries. Furthermore, as not all injuries occur while performing fire suppression tasks, the impacts of different firefighter clothing in general (e.g., daily station wear) on mobility may be of value. However, there is no known research comparing different clothing variations and firefighter mobility specifically. As such, the aim of this research was to compare the impacts on firefighter mobility of three different clothing variati...