Sit-ups Suck, Don’t Work Your Abs
By Jason
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All this time you thought those thousands of sit-ups were going to build you a six pack… only to have me tell you that you might have been wasting your time.
The truth is that sit-ups only work your abs indirectly. All that time that you spent doing those sit-ups was really a greater benefit to your hip flexors than for your abs. Were you not trying to build up tough hip flexors with your sit-ups? If not, I’m sorry to be the one to bring you the bad news. I’ll explain what all of this means.
How your abs work:
Muscles work through contraction. To put it simply, when a muscle contracts, it becomes shorter in length as the fibers pull together. So let’s think about what this means for your abdominals. What happens when your abdominals contract?
Again, when you abdominals contract, the muscles of your stomach area pull together and essentially become shorter, thereby moving the skeletal structure they are attached to. This contraction of the abdominals shortens your abdomen and pulls your rib cage and your shoulders toward your hips (see the picture up top).
Pulling your shoulders toward your hips is exactly the type of movement we see in the various types of stomach crunch exercises. A proper crunch will keep your lower back flat to the ground, and as your shoulders are pulled toward your hips, your spine will also inevitably bend and flex. This is what we call spinal flexion.
Crunches aren’t for sissies though. The range of motion for these is quite small, so they don’t look as impressive as a full sit-up, but a well-executed crunch will place intense stress on your abs and create a burn.
Focus on really pulling with the stomach muscles and squeezing them at the top of the movement for a moment. Like any other exercise, adding weight is important, but we’ll talk about ways to do that another day.
Why sit-ups don’t work (very well):
Here’s the bad news: all of that great spinal flexion and pulling with the abs doesn’t happen very much when you do sit-ups. Think about what’s happening when you do sit-ups. Your body is bending at the hips to pull your torso upward. This is called hip flexion, and it doesn’t use your abs nearly as much.
The beginning of the sit-up movement is the most effective part for your abs. The sit-up begins by pulling with the abs for about the first 30-45 degrees of the movement. That’s the good news.
The bad news is that the rest of the movement is done by your hip flexors. The hip flexors are a little group of muscles that help connect your femur (leg bone) to your back bone/ pelvis (check out the picture on the left).
Once your abs have completed the first 30-45 degrees of movement in your sit-up, they then begin to act only as stabilizer muscles. They hold your upper body in that flexed position isometrically while your hip flexors do the dirty work to pull your body upward at the hips. So your abs are indirectly involved in the movement, and this explains why they can get a little sore when you do sit-ups, especially if you have weak abs.
Don’t believe me? Try it for yourself right now. Stand in a doorway and hold on with one hand for stability. Place your other hand on your abs to see how much they flex. Now, raise your leg straight up in front of you. You will feel tightness in the top of your thigh, but not your abs. Leg raises and sit-ups are essentially the same movement in reverse.
Unfortunately, studies have shown that our ab muscles do less and less work as we become more tired during a set of sit-ups. This makes perfect sense. Think about it for a moment… when you do a set of sit-ups, is every sit-up performed just like the first sit-up you did?
Do you lower your shoulders down all the way until they are flat, and then begin the next sit-up with spinal flexion and pull your shoulders towards the hips? Or are you like the rest of us who just kinda forget about the whole spinal flexion part and make the movement into a simple hip flexor exercise? You don’t have to answer that one out loud.
You’ll also notice that the hip flexors attach to the pelvis and lower back… and fast sit-ups with rapid movements can cause an unsafe jerking and bending on your lower spine. Hip flexors that are too tight can also pull your pelvis until it’s tilted at the wrong angle. This can lead to a whole host of back problems and other pains that we’ll address another day.
Conclusion:
Sit-ups suck. Maybe that was too strong of a statement, because they do work your abs somewhat at the beginning of the movement and use them for stabilization throughout the remainder of the movement. But working your hip flexors has its draw backs, and if you are trying to tighten up your abdominals, your best shot is to focus more on the crunch movements that create the spinal flexion.
If your goal is to strengthen your abs, then focus first on the movements that will get the job done right.
Image credit: Fitstep.com
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Topics: Workout Principles |
February 25th, 2008 at 2:49 pm
Great article! It’s nice to see an article debunk the myth of situps! It never seizes to amaze me how many poor souls do thousands of situps in the gym thinking they can tone up their abs that way, but little do they now there is no such thing as spot reduction and set after set of situps isn’t going to cut it. Me personally I like weighted crunches.
February 25th, 2008 at 6:02 pm
Sean- That’s true, spot reduction doesn’t work. There’s no way that you can remove the fat from your stomach only by doing ab workouts. And weighted crunches are a great way to go… there are many way to do these as well.
March 1st, 2008 at 3:01 am
Great article, Jason. Your write ups are always detailed, yet 100% understandable!
Usually when I do situps/crunches, I would do like 3 sets and with each set I would do a different variation, like either crunches or legs in the air crunches etc etc. But which ab exercises do help burn that unwanted stomach fat?
March 2nd, 2008 at 11:57 pm
Richard- Great question. The answer is that none of the ab exercises are particularly helpful for burning your unwanted stomach fat. Sean made the comment above that there is no spot reduction of fat. Basically that means that you can’t lose the fat in just your stomach without losing fat all over your body. You can’t take it off of just one place.
Ab exercises do increase the lean muscle of the abdomen, and that muscle does consume more calories which means you end up with less of a gut… but that’s the same for any muscle you are working. Squats build more muscle overall and therefore burn more fat in the long run. Situps build muscle on your stomach (which you’ll need to get a six pack), but don’t necessarily do more than other lifts to take the fat off of it so that you can see the six pack.