While all waist exercises are beneficial in some form or another for strength or muscle building purposes not all waist exercises will slim your waist and carve out sexy hourglass figure curves.
Here's a quick how to slim your waist exercise tutorial that shows you the waist cinching moves that work best and why plus a quick rundown of core exercises to do in moderation or avoid all together if your goal is to sculpt a curvy sexy waist.
The reverse plank looks similar to the tabletop, an exercise that is featured on this site and in many YBFF workout routines quite often. But the reason this move is even better than the tabletop is that it requires the entire core (shoulders/back/abs/hips) along with the pelvic floor to work even harder. Did you know that the pelvic floor is tied to your deep abdominals and can help cinch in your waist.
See every time you elevate the spine from a vulnerable position your pelvic floor and internal corset muscles should cinch up and in to protect your spine. So any exercise that trains this integrated movement makes the entire internal corset stronger and shrinks your waist from the inside out while also flattening your abs.
Get started with the ball plank version here. You can also do it with feet on exercise straps, bench, or floor. The main thing to focus on with this move for it to work is shoulder blades together and down, hips elevated, pelvic floor squeezing up and legs arms chest neck head relaxed but firm. If you get all that down the transversus abdominis (corset muscle) contraction will happen easily and naturally at the beginning of each rep.
One of the fastest ways to a slimmer waist is to train your butt and every single version of the deadlift does this but the single leg deadlift engages the entire core and posterior chain which makes it the most effective of all the deadlifts for slimming the waist. In fact when you do this exercise correctly you will actually feel your waist cinching tighter to support your spine in that bent over position which takes you through a range of motion called "the critical point". It is at this bent over point that your transversus abdominis and other internal corset muscles must fire effectively to protect your low back from damage.
Many of my clients with a weak core and thick waist HATE this exercise because it is incredibly challenging for them but getting better at this move with all types of weights (dumbbells, balls, bars) is the secret to a healthier back as well as a smaller waist and flatter abs.
You can also practice the yoga version of this exercise which is called warrior 3. The easiest way is to start from warrior 2 then flow forward into warrior 3 without overextending the supporting knee and making sure to keep the core and entire back engaged. You can also approach this pose from crescent pose which is a deep lunge with arms overhead but this requires a lot more balance.
Sounds crazy that a dance move like the splits could get you a curvier sexier more hourglass shaped waist but it's absolutely true. Now you're probably wondering how a move that stretches the hamstrings could do this but this is where you're missing the point of splits which is hip flexor strength and length. Without hip flexor strength and flexibility you can't do the splits no matter how flexible your hamstrings are which why some yogis end up with torn knee ligaments, over-stretched hamstrings and terrible back problems.
I've featured several exercises to strengthen your hip flexors in the past including the shinbox getup, the sit thru or pilates can can. Check out my sexiest female body circuit to try those out. But I haven't focused much on how to improve flexibility of your hip flexors so that muscle begins to relax and allows your deep abs to function more effectively which cinches the waist even tighter. The yoga stretches pictured here are the best ones to do after lower body workouts to stretch the entire hip area effectively so that you can work your way into the splits.
But even if you're never able to do the splits because of other limitations practicing these yoga stretches will get you the waist cinching effect you're after and can improve your mobility with many other waist and booty exercises featured on this site.
I wrote an entire article on the worst and best waist exercises but in case you need a reminder or don't feel like clicking over to read it here's the exercises to avoid if you want to strengthen your core while carving out hourglass curves: