Gist
Yes. Hack squats are one of the clearest machine-based options for progressively loading the quadriceps through a stable path.
Yes. Deep, progressively loaded hack squats can train the glutes, although machine design and foot placement strongly affect the hip demand.
They train the core to stabilise the trunk over a wide base, though the movement is still primarily a lower-body exercise.
The calves help stabilise the feet and ankles, but the wide stance does not turn the squat into a strong calf-building exercise.
The hamstrings contribute to hip control, yet sumo squats are still a secondary hamstring exercise rather than a substitute for hinges and curls.
Yes. The quads still extend the knees in a wide-stance squat, although an extremely wide stance can change the balance of work toward the hips.
Yes, through anti-rotation and balance. The offset stance makes the trunk resist sway, particularly when the load is held asymmetrically.
The front-leg calf works to stabilise the ankle and balance the body, although direct calf training is still needed for the most predictable growth.
They can train the hamstrings as hip extensors and stabilisers, particularly with trunk flexion, but direct hamstring work remains useful.