Muscle forces and activation patterns in the spine during spine stabilization exercise using a whole body tilt device

Abstract

The objective of the study was to investigate the effect of 3-D stabilization exercise using a whole body tilt device. A musculoskeletal (MS) model of the whole body was developed, and used to calculate the forces in the spine, assisted by EMG measurement. The inverse dynamics was solved using the MS model of the whole body with the input data of the eight different directions of the tilt: anterior (A), posterior (P), anterior right (AR), posterior right (PR), anterior left (AL), posterior left (PL), right (R), and left (L), replicating the tilting directions of the whole body device. The anterior and posterior directions of tilt mainly induced superficial back and front muscle activations, respectively. However, deep muscles, such as the semispinalis and mulifidi, were activated in all directions of tilt. The joint resultant forces in the right and left direction of tilt were the least; but some higher activations and more diverse recruitments of muscles were demanded. In the present investigation, 3-D stabilization exercise can provide considerable muscle activation and exercise effect, with the minimum perturbation of structure. Therefore, the proposed direction of tilt can be used to strengthen the targeted muscles, depending on the patient’s muscle conditions.