Fig. 2.

Graphic representations of the post hoc analyses of the MF-SEMG fatigue normalized to onsets. This figure shows the simple box plots of the MF-SEMG fatigue slopes normalized to their onsets (%/s) that were recorded from cLBP patients during a 30 s sustained back extension test performed in a seated position. The box plots are provided for the different electrode recording sites according to the four different groups investigated. These groups were the male cLBP participants younger and older than 50 years of age (“< 50.M”,“> 50.M”), and the female cLBP participants younger and older than 50 years of age (“< 50.F” or “> 50.F”). Please note that results of the unpaired t tests suggest that the MF-SEMG slopes significantly differed from zero at all electrode sites investigated and for all the age- and sex-specific subgroups (p < 0.0025). Please see also Table 2