Though the hip flexors are the primary movers in the GHD sit-up, the abs play a strong role in stabilizing the torso to prevent hyperextension of the spine. This is, in our opinion, a more functional role for the abs than trunk flexion. Carefully introduced and practiced, the GHD sit-up is a potent tool for reeducating the athlete to use the hip flexors more efficaciously and safely.

Dave Eubanks (CF-L4) discusses the importance of the overhead squat with a group of participants at a CrossFit Level 1 Certificate Course at CrossFit SAC on Nov. 9, 2019.