Fig. 1

Experimental setup showing participant’s posture on a chair without back support during sitting balance assessments. The force plate was positioned on the seat surface, under the buttocks, to capture trunk sway, while the participant’s feet were not supported on the ground and the participants had their arms crossed on their chest. The figure also shows the: a front view of the participant illustrating the approximate location of the FES electrodes on the rectus abdominis (RA) muscle and; b back view of the participant illustrating the approximate location of the of the FES electrodes on the lumbar erector spinae (L3) muscle. The RA and L3 muscles were stimulated bilaterally and were activated simultaneously to generate co-activations