Even when my personal training clients could work out in a gym, many of them had foot or knee injuries that made them unable to do jumping workouts. If you need low-impact alternatives for your knees or your neighbors, no-jump jumping jacks are a solid option.

Instead of hopping your feet out, step them out quickly (with each rep, alternate which foot you lead with, giving your coordination a workout, too). Be explosive with your arms coming over the top of your head, making sure to move gently and with bent elbows if your shoulders are acting up. As you do your quick step outs, land on the balls of your feet — a balance challenge that will work your core and calves like jumping would — and bend your knees generously to sink down into a light squat. That will help jack up your heart rate. Try "jumping" for 30 seconds, a minute, or however long your workout video wants you to.

Sure, they're not necessarily explosive, but because split squats engage every big muscle group from your core down, they'll get your heart rate and strength up without a sound.

Set up like you're going to do a lunge. Step out with your left foot and bend both legs so they're near 90 degrees. Keep your front knee tracking over your toe, and square your hips by pushing your right hip slightly forward and pulling your left hip slightly back. Rise to a stand and sink back down, bringing your back knee as close to the ground as feels comfortable. No need to move your feet throughout this movement, which is what makes it such a great silent exercise. Just switch sides when you've completed 10 or 15 reps and even it out.

Step back with your left foot into a reverse lunge. Keep your chest tall and make sure your right knee is tracking over your toes rather than straining behind or way in front of them. You might have to experiment with your foot spacing to get it right. Your left knee can come close to the ground or even touch it lightly — just make sure it doesn't slam down.

Keeping your core tight, come back to standing. But instead of just standing, transition your weight into your right leg so that when your left foot comes forward, you can kick it out in front of you. The kick doesn't need to be high (especially if you're not accustomed to using your hamstrings like this), so focus at first on keeping your balance rather than power. Repeat for 10 to 15 reps per side, keeping your torso upright throughout. You'll get a good cardio workout and strengthen your legs without a jump in earshot.

Whenever you do plyometric work, keep a small bend in your joints so you land softly to avoid injury. But even landing with good form is going to sound like a huge series of bangs when you're doing clapping pushups on your neighbor's ceiling.

To avoid being That Jerk, drop to your knees. Sink down into your pushup as slowly as you can, with a lot of tension in your core and control in your upper body. When your chest touches the ground, or hovers just above it, push your palms down hard so that your upper body explodes upward. Let your hands release from the floor as your torso rises. But, because you're on your knees, you can slow your descent, using your core to pause with your hands off the ground and come back down softly. You'll get the plyometric benefits from combining a very slow descent with an explosive ascent, but with none of the noise.

You'll use the same principle here as you did with the "clapping" pushups. Descend into your squat very, very slowly. When you think you're going slowly enough, go slower. You want to really focus on your form, like you're sitting back on a chair slightly behind you. Keep your chest up throughout.

Sink down to the bottom of your squat (this will look different for everyone, and that's OK). Then, explode back up to standing. Aim to move so quickly that your body feels like it's about to take off — rise onto your tip toes with the force of your ascent. That will add an extra cardio and calf strength element to this jump-free jump squat. Go for as many reps or as much time as your video wants you to, or build your own sets of 30 seconds each.

Your workout video might tell you to leap up, gazelle-style, and switch your legs in midair so that you sink into a lunge with the opposite foot placement from what you started with. That might be all well and good when you live on the first floor, but with neighbors, you'll want to transform your leap into a very quick two-step.

Descend very slowly, then spring back up to standing quickly. Land on the balls of your feet with both legs right underneath you and switch legs right away, going back into your second lunge. You won't be jumping, but you'll still be building leg strength and a quick heart rate — not to mention an improved sense of balance and coordination. Try going for a whole minute.

Burpees don't have to be explosive to be effective. When you sink down to hit the floor (your goal is to land in a plank position), you can step your feet back instead of leaping. You can also plant your hands firmly on the ground first, then do a soft hop back — especially if you've got a yoga mat and/or carpet in your apartment, a soft hop will be pretty quiet.

When you come back to standing, you can repeat the movement in reverse, either stepping up or doing a soft hop to cushion the thump. Instead of topping the move off with the traditional jump, you can reach your arms over your head and rise onto your tiptoes. Try to see how many reps you can get in a minute. That way, you can be both the master of all things full-body burpee workout and be an A+ upstairs neighbor.