They wiggle. They jiggle. They may even make you want to cover up with a cardigan on an 85-degree day. We’re talking about your arms, people.

And while diet and genetics play a big role in the shape of your arms, exercise is the key to keeping them looking toned and tight. But which move is the best at banishing that irksome under-arm flab?

The American Council on Exercise decided to find out, seeking the holy grail of arm exercises by commissioning researchers at the University of Wisconsin-La Crosse to compare the effectiveness of eight different arm exercises: triceps kickbacks, overhead triceps extensions, bar push-downs, rope push-downs, closed-grip bench press, lying barbell triceps extensions, triceps dips and triangle push-ups. In the study, researchers applied electromyographic electrodes on the back of each subject’s upper arm to record real-time muscle activity.The hands-down winner and biggest bang for your buck: Triangle push-ups.“The triangle pushup really targets all of the major elements of the triceps muscle—the long and lateral heads of the muscle,” explained Cedric X. Bryant, Ph.D., Chief Science Officer at ACE. “It elicited the most muscle activity.”Bonus: Since push-ups put you in a plank position, you are also engaging and strengthening your core as you work on toning your arms.Sold? We thought so. Here’s how to do a proper triangle push-up, according to Bryant:

triangle push up

First, adopt a plank position with your head in line with your spine and contract your core abdominal muscles, glutes and quadriceps. For hand placement, have your thumbs touching and forefingers touching so they form a triangle—“this is how the exercise gets its name,” notes Bryant. Place your hands directly under the middle of your breastbone, in line with your shoulders. Maintain plank position by keeping your abdominals, glutes and quads engaged as you lower and raise your body. Do not allow your back to sag or hips to hike upward as you perform the up-and-down movement of the push-up.

If starting in plank position is too challenging, modify the move by placing your knees on the floor or doing triangle push-ups against the wall, while keeping your head in line with your spine. Bryant recommends doing 1 to 3 sets of 8 to 15 repetitions.And then get ready to say farewell to flabby arms.