The existing full-body-lumbar-spine (FBLS) model was adapted and validated for lifting motions to produce the lifting full-body (LFB) model to estimate spinal loads during lifting. The model was validated through comparisons with experimental electromyography muscle activity, reported intradiscal pressures, and reported vertebral body implant measurements. The validation results demonstrated the suitability of this model to evaluate changes in lumbar loading during lifting.