They reported no difference in either upper or lower erector spinae muscle activity during the ascending phase of the lift. (strengthandconditioningresearch.com)
Assessing the effects of stability during split squats, Andersen et al. (2014) explored erector spinae muscle activity in the split squat with the foot placed on the floor or on a foam cushion, using 6RM. (strengthandconditioningresearch.com)
Erector spinae muscle activity tended to be highest in the side plank compared to the other exercises. (strengthandconditioningresearch.com)