There is more than one right way to perform a HIIT routine, so why do the same push-recover-repeat mix every time? (See: Is It Bad to Do the Same Workout Every Day?)
"If you're constantly switching up the equipment you use, the exercises you do, the resistance, and the timing and patterns of your workout, your body never gets used to any one form of training," says Rob Deutsch, the founder and co-owner of F45, a functional training gym with over 1150 locations worldwide. Such variety, he says, is exactly what helps keep your metabolism stoked. (See how one F45 co-owner de-stokes and makes time for self-care.)
Your body needs to work harder to adjust to different exercises, greater loads, or a new rep scheme, which results in a higher calorie burn, Deutsch continues. Varying the timing of intervals also plays a crucial role: Switching back and forth between cardio bursts that spike the heart rate and strength-training sets that let your heart rate level out challenges your system—and routinely recalibrating them gets you even fitter.
"At F45 you'll never move around the room the same way," Deutsch says of the studio's circuit-style training. One class, dubbed "Firestorm," has a whopping 54 stations, while "Hollywood" has 27 stations. "Benches, barbells, and dumbbells are staples, but we also bring in ropes, boxes, sandbags, sleds, bands, slam balls, Bosu balls, and more," he says.
In fact, to sell you on the power of adding some fresh stations to your usual circuit, we asked Chris Barnes, F45's athletic director, to create a total-body HIIT workout exclusively for Shape using—besides your body weight—an old-school Bosu ball. If you haven't used one of these in inflated rubber mini domes before (you can get the original Bosu Balance Trainer for around $100 on amazon.com), it can be used in extremely versatile ways and has about the same effect as exercising while standing in a canoe would. (Also try testing your skills with this balance test.)
"When you're on an unstable surface, your central nervous system is sent into overdrive, firing off signals to stabilizing muscles that you don't use in everyday life," Deutsch says of its shock-your-body benefits. You're working at a greater rate, which means you're burning more calories and building muscle. You'll also fire up your core as it works to keep you balanced. (No Bosu on hand? Try this tabata workout that'll improve your balance.)
Follow the circuit through, and, post-workout, you should feel it in a few spots that you typically wouldn't with your current drill. Remember, you've always got the option to mix it up—we'll get you started with some suggestions below. Let those spark you to reboot your next workout.
How it works: Start with a four-minute dynamic warm-up, including jumping jacks, high knees, and lunges. Then do this circuit three times through.
Total Time: up to 15 minutes
1. Bosu Run-Off
Place Bosu on floor (dome side up) and stand about a foot behind it. Quickly step on top of Bosu dome with right foot first, then left.
Immediately return to start, stepping down with right foot, then left. Continue as fast as you can for 30 seconds.
AMRAP for 30 seconds
Scale down: Slow down speed from a run to a brisk walk.
2. Bosu Ab Chopper
With Bosu on floor (dome side up), lie faceup with lower back on center of Bosu dome, right leg bent, foot flat on floor, left leg extended straight hovering off floor. Extend right arm overhead and left arm down by side.
Crunch up, lifting torso and left leg off floor and reaching right hand to outside of left knee. Return to start. Switch sides; repeat. That's 1 rep.
Scale up: Extend both legs to hover off floor in start position, then perform reps.
3. Frog Squat
Stand with feet slightly wider than hip-width apart, then lower into a squat to start (hip crease slightly lower than knees), holding inside of each ankle (arms between knees) with hands.
Raise hips up until knees are just slightly bent. Return to starting squat position.
Scale up: Decrease range of motion and do tiny pulses, keeping weight in heels.
4. Plyo Lunge and Twist
Start in a lunge position with left leg forward and both knees bent to 90-degree angles. Twist upper body toward left.
Jump up and switch legs midair, landing with right leg forward and twisting torso toward right.
AMRAP for 30 seconds
Scale down: Skip the jump and step into each lunge position.
5. Bosu Burpee
Place Bosu on floor with dome side down and start in plank position with hands gripping edges of Bosu base and feet on floor.
Jump feet up toward Bosu to outside of hands, landing in a squat position.
Stand straight up, lifting Bosu in front of chest, then press it overhead. Reverse motion back to start.
Scale up: Skip the jump and step into each lunge position.
6. Bosu Crossover
Place Bosu on floor (dome side up) and stand with left foot atop center of Bosu and right foot on floor to right of Bosu. Lower into a squat to start.
Press into floor and Bosu with feet to jump up.
Switch feet in midair so that right foot lands atop center of Bosu and left foot lands on floor to left of Bosu. Continue alternating.
AMRAP for 30 seconds
Scale down: Omit jump and stay low in squat position as you switch leg position, quickly tapping feet to floor as you alternate.
7. Handstand Walk in and Out
Start on floor in plank on palms with feet wide apart.
Do a push-up.
Keeping legs straight, walk hands back toward feet, allowing heels to rest on floor as you reach a jackknife position. Walk hands back to start.
AMRAP for 30 seconds
Scale up: Add 10 mountain climbers (5 on each side) after push-up.
8. Lateral Shoot-Through
Start on floor in plank on palms. Bend legs so knees are directly under hips, hovering a few inches off floor (crouch position).
Twist torso toward right, kicking left leg under body toward right while raising right arm behind head, elbow bent. Reverse movement back to crouch position. Switch sides; repeat.
AMRAP for 1 minute
Scale down: Return knees to floor when switching sides.
Scale up: Briefly tap glute to floor after kicking leg through.