Why it made the list: Decline-bench crunches amp up the challenge by increasing the range of motion over standard crunches, and you can dial up (or down) the degree of difficulty by adjusting the angle of the bench. Adding a medicine ball or weight plate against your chest adds a further level of customizable resistance. This also allows you to manipulate where you want to fail: low, medium, or high reps.
Here’s a how a standard HIIT routine goes: one minute of strenuous exercise followed by 30 seconds of rest, repeated four to six times. You can do it for anything: sprinting followed by walking; biking full-steam followed by a casual pace; butterfly strokes followed by a doggy paddle. Or, if you really want to turn up the heat on HIIT, try out The Single Best HIIT Workout For Turning Back the Clock.
Start lying faceup on the mat. Lift head, shoulder blades, and feet off floor as you extend arms straight out. Neck should be relaxed, not strained. This is your hollow hold. Next, engage abs to lift chest towards legs as you bend knees so that body forms a V shape and shins are parallel to floor. Slowly lower back down to a hollow hold position and repeat.
To do it: Lie on your back with your hands interlaced behind head, knees bent ,and feet hip-width apart on the floor. Inhale and lift your chest towards your knees, bringing your shoulders and head off the floor, maintaining a neutral pelvis (keeping it parallel to the floor). Exhale and rotate to the right side, and then exhale again rotating even further, lifting a little higher. Next, inhale and lift as you return to the center and repeat to the other side. Do 8-10 reps per side.
But you can still go wrong. Because your feet are hooked, it's all too easy to pull through your thighs. Nor do you want to go all the way down to rest on the bench between reps; stay well off it. If you're not feeling a wicked burn, drop all the weight, put your hands on your belly, and really focus on the contraction at a slower pace. You can also introduce a cross-body movement, angling your elbow to the opposite-side thigh, to better engage the obliques.
When guys talk about six-packs, they are really talking about one muscle, called the rectus abdominis. “The rectus abdominis runs from our lower ribs down to the top of our pubic bone, and fibrous bands of tissue break up the muscle along the way to give us the six-pack look we all desire,” explains kinesiologist David Cary, C.P.T., a T4 Coach at Equinox in Chicago. So, if you want to sprout six-pack abs, this is the muscle you need to work.
“For me, getting a six-pack was about paying attention to what I was eating and lifting heavy weights at CrossFit. I do have a semi-strict diet, and I loosely count macros (focusing on daily carbs, protein, and fat intake rather than blindly counting calories) to stay balanced and on track. It sounds like a lot of work, but it really isn’t. Eventually, it just became a part of my lifestyle, and it’s something I enjoy doing. I even started a custom meal-plan business based on macros because I had such great results!” —Tina Haupert, @carrotsncake