The problem with classic ab exercises like sit-ups and crunches is that they put your the top portion of your spine (the cervical vertabrae) in flexion. In a world where you spend a good portion of your day with your head jutting forward as you stare into a smartphone, exercises that promote this poor posture are probably a bad idea.Worse, golfers who stand over the ball with their upper back rounded, shoulders and head forward, are really going to struggle to swing a golf club on plane. If you want to slice a ball, stand over it in this posture, says David Leadbetter, one of Golf Digest’s Legends of Golf Instruction.Knowing that you should be doing everything you can to get your head and shoulders pulled back, you might be wondering what you can replace crunches and sit-ups with to strengthen your abdomen muscles. We asked a few Golf Digest Certified Fitness Trainers to share their favorite ab exercises for golfers. Here’s what they gave us:

LIFTED BEAR POSITION ARM REACHES (Andrew Dulak)

“I love this exercise for golfers because lifting the knees off the ground one or two inches engages the core and requires stability to allow for the upper body to dissociate with rotation,” Dulak says.

SUPINE PELVIC ROCKING (Pam Owens)

“Raising and lowering the pelvis while resting on an elevated cushion like a yoga block, legs braced against the wall, trains your lower-core muscles to help you get into a better impact position when you play golf,” Owens says.

MORE: These “hidden” muscles could be the source of your back pain

STANDING CROSS CRAWLS (Karen Palacios-Jansen)

“I like rotational core exercises for golfers because, while they target your core, they also help you practice ‘separation,’ a crucial move in the golf swing that allows proper sequencing between your upper and lower body,” Palacios-Jansen says. “Like in a golf swing, standing cross crawls rotate your torso independently from your hips. It also requires coordination between both hemispheres of the brain, adding the extra benefit of improving overall motor control.”

MED-BALL WALKOUTS (Paul Gozbekian)

“I like this for abs/core tensioning, and it requires a lot more core stabilization as well as shoulder stability,” Gozbekian says. “There is constant movement with the hands walking the med-ball out, which makes the exercise more dynamic. There is a high demand for proper spinal alignment from head down to the sacrum. Also, it is scalable. Some clients can walk out just a little, while others can extend fully. Additionally, while you start from a kneeling position, you can progress to a full standing position.”

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