HOW TO DO IT: Start in a high plank. Push your hips back without arching your lower back until your knees flex to about 90 degrees. Pause for a beat, then explosively extend through your knees, ankles and hips while also pulling with your upper back as you lower into the bottom of a push-up. Keep your elbows tucked into your sides to protect your shoulders. Skip the push-up and just maintain a hold if you need it to be easier.
Bend your knees and push your butt back toward your heels, and then explode from that position back to a high plank and immediately bend your elbows and bring your chest toward the ground to do a push-up. As you bend your elbows and lower toward the ground, your elbows should be at about a 45-degree angle to your body (though you can make adjustments based on what feels best for your shoulders).
HOW TO DO IT: Assume a seated position with your palms loaded, hands underneath your shoulders and knees bent at 90-degrees with your feet underneath your hips. Raise your hips so your butt hovers above the ground, and then move your right hand and left foot forward. Continue this opposite-hand, opposite-food pattern as you crawl for 30 to 60 seconds. You can add difficulty by traveling backwards or side-to-side.
HOW TO DO IT: Assume a bent-knee push-up position with your hands underneath your shoulders and your knees bent at 90-degrees, feet underneath hips. Step your left hand and your right foot forward and continue to crawl forward so that your opposite hand and foot are moving together. Repeat for 30 to 60 seconds. Start with smaller, slower steps and gradually increase the speed and distance traveled per step over time.
If you're ready to move on from classic Bulgarian split squats, Swan's amped-up variation gets your upper body in on the action for a true total-body exercise. "This combination move works your legs, butt, chest, back, arms, and core," she says. "And it not only hits all the major muscle groups—it also lets you work on balance." Give it a shot and you'll see why.