If you're tired of doing the same ab circuit over and over, standing ab exercises can help you mix up your workouts. "They are a great way to add variety to your workout and stop your abdominal routine from becoming stale," says certified Pilates instructor Nicole de Souza.

Why Standing Ab Exercises are Effective

The novelty of these exercises not only make your workouts more enjoyable, but they can also stimulate your core muscles more effectively: "Once your muscles get used to a certain exercise, they stop changing, so standing ab exercises are a wonderful way to spice up your routine," she explains.

Engaging Your Core for a Good Burn

If you want your upright ab work to be truly effective, though, get used the term "core engagement." If you've tried standing ab exercises without feeling that they're actually working your abs, de Souza has some cues to make sure you're digging into your core for a good burn.

"You must first and foremost connect with your deep core abdominals by pulling your belly button gently towards the spine, breathe throughout, and make sure every movement is performed slowly and with control," she says.

Standing Ab Exercises to Try

BODi offers plenty of ways to get a killer ab workout at home, but try adding these standing ab exercises to your core-chiseling routine:

1. Standing Twist

Stand with your feet hip-width apart and a slight bend in your knees, holding one suitably weighted dumbbell in both hands. Extend your arms forward in line with the chest.

Engage your core by pulling your belly button toward your spine as you twist your torso to one side. Keep your hips facing forward throughout the movement.

Slowly return to center, keeping your abs engaged and the movement controlled. Repeat on the other side.

Trainer tip: Try doing 10 to 15 slow twists to each side to really work your obliques, suggests de Souza.

2. Standing Woodchop

Stand with your feet hip-width apart and a slight bend in your knees, holding one suitably weighted dumbbell in both hands.

Engage the core as you slowly lift the weight diagonally above your head with straight arms, twisting to the right and pivoting on your left foot.

Slowly bring the weight down (as if chopping wood) as you twist to the left. Come into a squat position, holding the dumbbell on the outside of your left leg.

Trainer tip: The focus should be initiating and controlling this movement with your abdominals rather than relying on momentum, de Souza explains. She suggests doing 10 reps on each side.

3. Power Knees

Stand with your feet hip-width apart.

Step the right leg straight back behind you as you bend into the left knee, your weight anchored into the left foot.

Hinge forward at the hips and extend both arms overhead. (There should be a straight line from your arms to back toes.)

Engage your core, squeezing the abdominals to lift your right knee toward your chest as your arms pull in at your sides.

Replace your leg on the floor and, as quickly as possible, repeat the move.

Trainer tip: You're getting some calorie-burning cardio in with this move, but don't rely on momentum. Instead, you want controlled movements with your ab muscles engaged. Do 20 reps on one leg, then switch sides.

4. Triangle Reverse

Stand with your feet wider than shoulder-width apart, left toes pointed forward and right toes turned out, pointing to the side.

Reach your right arm over your head as you lean your body toward your left leg.

Slide your left hand down your left leg. Keep your core engaged and shoulders down.

You can slightly bend your left knee and rest your left arm on your left thigh if it helps with stability.

Use your abs to bring you back to center, then reach your left arm over your head as you lean toward your right, sliding your right hand down your right leg as you get further into the stretch. That's one rep.

Trainer tip: The key to this exercise is to move fluidly, says de Souza. Make sure to feel your whole side working to pull you from side to side. Shoot for 10-15 reps on each side.

5. Single Leg [TAG9] Arm Circles

Stand tall with your feet hip-width apart.

Engage your abdominal muscles and maintain a neutral spine as you bend one knee and lift it up to hip height.

Keep both hips level as you extend both arms out to the side.

Use your arms to trace a small circle 2 or 3 times to the front and to the side to challenge balance and stability.

Return your foot to the floor and repeat on the other leg.

Trainer tip: The challenge in this exercise, de Souza explains, is to try to avoid swaying or tilting your upper body. Focus on maintaining balance and alignment. Alternate legs and try to do 5-10 repetitions on each side.

6. Wacky Jacks

Stand with your feet hip-width apart and knees slightly bent.

Bring your arms up to the side and bend your elbows at 90 degrees so that the tips of your fingers point to the ceiling.

Explosively lift your right knee up and out, like you're trying to touch it to your right elbow.

Return your right foot to the floor.

Repeat with your left leg.

Try to flow between legs smoothly and with control.

Trainer tip: Engage your abs as you pull each knee up and soon enough you'll be feeling your abs and obliques light up. Aim for 20-30 total reps.

7. Snowboarders

Stand with your feet shoulder-width apart and knees slightly bent.

Bend your knees and push your hips back into a half squat position.

Raise your arms out to the side and turn your head to look to your right.

Keeping your legs the same distance apart, hop and spin 180 degrees, so that your feet switch positions.

Repeat, hopping in the opposite direction, to return your feet to the starting position.

Keep your gaze in the same direction for the whole exercise.

Trainer tip: You'll work your legs getting the momentum you need to hop and spin, but your abs will get a workout as they keep your trunk locked into position. Repeat 10-15 hops in each direction.