Quantitative Evaluation of Spinal Kinematics during High-Load Squat and Deadlift Exercises in the Sagittal Plane

Abstract

This study aimed to compare the spinal kinematics of the squat and deadlift at high load weights using a model in which the trunk is divided into multiple rigid body segments. Thirteen subjects performed the squat and deadlift under load conditions of 90% of their one repetition maximum. Reflective markers were attached to distinct landmarks on the participants’ bodies; six markers were placed at the tips of specific spinous processes, thus creating a two-dimensional trunk model with six rigid body segments on the sagittal plane. In addition, a three-dimensional optical motion capture system with 12 cameras was used. Regarding angular displacement by spine region, both exercises showed greater angular displacement at L3 and S1. In the angular displacement curves by spine region, the deadlift showed significantly greater flexion angle displacement at T12 and L3 than the squat from 0-98%, 0-99% of the time. In conclusion, the deadlift lifts with the lumbar vertebrae flexed compared to the squat, so that the mechanical stress may be concentrated on the lumbar vertebrae.