You’re working your shoulders, as the name suggests, but the stability required for this move also requires a good amount of core and glute activation, Lai adds. “Of course, other than the shoulders, your arms are holding you up, so expect some toning in those arms,” she says. And as you get better at working this move, you can also speed it up, which will elevate your heart rate and add some cardio. And to make them harder, as Lai mentions, you can try speeding it up. You can also hold the taps for a few seconds to add intensity. Another option for adding more of a challenge is to lift your opposite leg with every shoulder tap, which will work the backs of your legs and glutes. On top of that, Lai notes, core stability is super important. “You always want to make sure you’re using the bracing technique, where you hold your core like you’re wearing a corset,” she explains. “This ensures that your body is as still as possible when doing your shoulder taps.” With the core engaged, you’re also protecting your low back from bearing too much pressure. And lastly, Lai says, you want to keep the hips and back as level as possible, avoiding rocking from side to side. “One thing I always say in class is that when you do shoulder taps, you should be able to balance a plate on your back,” she adds.