A 10-Minute Isometric Core Workout for a Slow but Serious Burn

When six-pack abs are the hallmark of fitness — the one thing that unequivocally makes people think, "Hey, that person is really fit!" — it's common to strive for a shredded stomach. But endless crunches and other ab exercises can get boring — and sometimes don't even work (looking at you, sit-ups).

Having six-pack abs would be nice, but a washboard tummy doesn't always equate to a strong core — and a strong core is what's important for overall health and fitness.

Your core protects your spine and also initiates almost every movement: From standing up to walking to lying down, your core muscles — your abs, of course, but also your lower back, upper back, glutes and many muscles that move the hips — do a large part of the work. Because your core is so all-encompassing, a weak core can affect nearly everything you do.

This 10-minute workout can improve both your core strength and increase the musculature of your abdomen, which can result in a more defined look. In other words: You get the most bang for your buck.

This routine is entirely isometric, meaning you contract your muscles without actually moving them. Think of it as resisting movement instead of creating movement.

You're probably already familiar with one of the best isometric exercises for core strength: the plank. You'll perform planks and more ab-burning holds in the quick workout below.

Do: Each move for 30 seconds. Rest for 30 seconds when indicated. Complete the whole circuit twice.

• Low plank
• High plank
• Bird dog (left leg)
• Bird dog (right leg)
• Rest
• Superman
• Boat pose
• Side plank (left)
• Side plank (right)
• Rest