At the top of the movement, the knees are bent, the hamstrings are shortened, and the glutes are contracting very hard. Anteroposterior flexion exercises are second only to anteroposterior straight-leg exercises in mean hamstring activity. Examples of anteroposterior flexion exercises are glute-ham raises, stability ball leg curls, gliding leg curls, and sliding leg curls.
However, during these exercises the glutes aren't placed under the same amount of stress at the bottom range of motion as squats or lunges, so they do not produce nearly as much glute soreness. Examples of bent-leg anteroposterior exercises are glute bridges, hip thrusts, pendulum quadruped hip extensions, bent leg back extensions, and bent leg reverse hypers.