Awesome Abs: What’s The Cheapest, Most Effective Piece of Equipment For Ab Workouts

I’ve seen people use sliding disks under their feet at the gym—but I have no idea what they’re doing or why they’re helpful. Explain.—Grace H.

Sliders, gliders, skimmers—whatever you call them, they’re deceptively innocent-looking. Usually round little pieces of plastic, you’ll see gym-goers integrating them into their bodyweight exercise routines by placing them under their hands and feet. Seems simple enough. But try them yourself, and you’ll see firsthand that movements that seemed like a breeze are suddenly impossible.

Here’s why: You’re used to a solid, stable surface under your feet. But step onto a set of skimmers (or even just use a hand or dish towel), and all of a sudden you look like Bambi on ice—your legs slide out from underneath you, you lose your balance, and it takes every muscle in your body not to fall flat on your face. Fun, right? Don’t worry, the first time is a little awkward, but you’ll get the hang of it pretty quickly, and it will benefit you in the long run.

By using the skimmers, you’re adding an extra element that tests your balance and core strength in even the easiest bodyweight exercises. Lunges. Planks. Push-ups. Squats. Add a skimmer or slider into any of these moves and you’ll feel your muscles quivering immediately—every exercise suddenly becomes more effective. Sliders are so versatile, and because it’s easy to integrate them into any floor workout, they’re one of my favorite pieces of equipment.

Another reason I love these babies? They’re cheap, light, and easy to pack. Sure, there are some branded versions that run about $30 a pop, but you can always use furniture movers if you’re looking for a lower-cost option that works just as well. (These are what I use at home!) If you’re in a serious pinch, use a dish or hand towel.

This summer I’m all about the abs—a stronger core helps prevent back pain and improves posture, even making it easier to lug your heavy suitcase around on summer vacation. But the last thing I want to do when I’m on vacay is waste 30 minutes doing crunches—thankfully, these towel abs are just as effective in less than half the time. Here are four plank exercises you can do with a hand towel to fire up your abs, fast! All you need is four minutes, and you’re golden. Need a refresher on how to do a perfect plank? Click here for a tutorial.

Knee tuck

Do: 30 reps

Tip: Create a 90-degree angle with your waist and your thighs. Resist the urge to bring your knees all the way up to your chest and chill in a sort of squat position—that won’t engage your abs.

Single leg mountain climber

Do: 15 reps on each leg

Tip: Keep your weight forward on your hands, and your tailbone in line with your shoulders the whole time. Too tough? Try double-leg mountain climbers instead, with a hand towel under each foot.

Plank kick out

Do: 20 reps

Tip: Try to kick legs directly to the side, not backward on the diagonal behind you. When your legs shoot out to the right, try to get your feet in line with your right shoulder. Repeat to the left for one rep.

Single leg circles

Do: 30 reps on each leg

Tip: Get as large of a range of motion as possible—no wimpy circles here!