Reducing lumbar spine loading in Russian bar porters: a case study

The Russian bar is an acrobatic circus discipline characterised by dynamic loading on a single shoulder, posing a risk for back injuries. The aim of this case study was to quantify and compare lumbar spine loads in porters using a novel symmetrical design and the traditional asymmetrical bar. Two male porters and one female flyer performed a series of candle jumps, saltos, and consecutive jumps using both bar designs. Motion capture, electromyography, and musculoskeletal modelling in OpenSim were used to quantify L4-L5 intervertebral forces and moments. Statistical comparisons were conducted using a multifactorial analysis of variance (ANOVA). The results showed that the symmetrical bar significantly reduced lumbar spine bending moments (2.1 times lower) and shear forces (2.2 times lower) compared to the traditional bar, with no significant differences in shoulder forces. Shoulder forces did not differ significantly between bar types, suggesting that the flyer's performance, particularly jump height, was not substantially affected by the change in bar design. This novel symmetric bar design may enhance the safety and carrier of Russian bar porters. Future research should investigate the long-term effects of this design and its impact on performance adaptation.