Why Crunches Don't Work?

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Stop Doing Sit-Ups: Why Crunches Don't Work

Kate Dailey

Everyone knows that the road to flat, tight abs is paved with crunches. Lots and

lots and lots of excruciating crunches. Or is it?

As it turns out, the exercises synonymous with strong, attractive abs may not be

the best way to train your core—and may be doing damage to your back.

" We stopped teaching people to do crunches a long, long time ago, " says Dr.

Guyer, president of the Texas Back Institute. That's because the " full

flex " movement—the actual " crunch " part of crunches – puts an unhealthy strain

on your back at its weakest point. The section with the most nerves (and most

potential for nerve damage) is in the back of the spine, which is the very part

that bends and strains during a sit-up.

" There are only so many bends or a `fatigue life', " in your spinal disks, " says

Stuart M. McGill, a professor of spine biomechanics at the University of

Waterloo. Inside each disk is a mucus-like nucleus, he says, and " if you keep

flexing your spine and bending the disk over and over again, that nucleus slowly

breaches the layers and causes a disk bulge, or a disk herniation. " A herniated

disk won't show through your swimsuit, but it's no fun, and can cause persistent

back and leg pain, weakness, and tingling.

Think of the oft-repeated advice for movers: bend at the hips and lift with your

legs, not your back. And what is a sit-up but a back bend done in a lying

position? " When people are doing curl up over gym balls and sit-ups, and this

kind of thing, they are replicating a very potent injury mechanism on their

back, " says McGill. " Every time they bend it they are one repetition closer to

damaging the disk. "

And of course, when people do crunches, they rarely stop at one or two: in the

quest for flat abs, they'll churn out dozens at a time, bringing them ever

closer to " flex intolerance " —so much pain and stiffness that it's difficult to

tie one's shoes or bend down to pick a penny off the ground.

But who cares about back health as bathing suit season approaches? Turns out,

crunches might not be the best solution for a flat stomach, either. That's

because doing too many sit-ups at the expense of other, more comprehensive

movements can lead to the dreaded " aerobic abs. " That's the term celebrity

trainer Steve Maresca coined to describe the distended stomachs of those who

focus only on the rectus abdominus muscles targeted by sit-ups and crunches.

" They look great from the front, but when they turn to the side, their stomachs

are extended, " he says. To get the long, lean look, one needs to work transverse

abdominius, a large muscle that holds in those rectus abs, and is mainly

unchallenged by traditional ab work (aka, the sit-up and crunches).

Doing a sit-up doesn't train your ab muscles to do the job for which they were

designed – keeping your spine straight and secure and providing power for your

movements. In everyday life, " the abdominals are braces, " says McGill, author of

" Ultimate Back Fitness and Performance " (Stuart McGill, 2004). When doing any

athletic movement—even opening a door— " the spine is in a neutral posture, not

flexed, and the abdominal muscles are contracted to brace the spine. "

The best way—for both your back and your beach body—to work your midsection is

to do movements that challenge the muscles to perform the way they're designed

and expected to work in real life, and not to train muscles in isolation. " It's

important to have strong abs, but strong abdominals are not the only thing, "

says Dr. Guyer. " You have your back extenders, your flexors, which are belly

muscles, you have your oblique muscles. " Working all of these muscle groups—the

anatomical association known as " the core " —is essential to both back health and

general athleticism.

As a result, only training for good-looking abs won't add to your athleticism or

overall strength. On the other hand, moves not traditionally designed for

good-looking abs can in fact help strengthen and tone those muscles.

Consider the pushup. Not usually thought of as a great ab move, the pushup

forces you to work several muscles at once: it forces your core muscles to

stabilize your trunk as your arms and back work to move the body up and down.

" Do you see how a pushup is a full body challenge? " says McGill. " It challenges

abdominals, front of your legs, your arms and your back. That is how you use

those muscles in real life. "

Like the pushup, the best exercises for back health and a firmer stomach are

ones that work your abs while holding your spine straight, like planks or leg

drops (done when you lie flat on your back, with your hands at the base of your

spine for added support. Raise your legs up at a 90 degree angle, then slowly

lower until they're only inches from the ground. Repeat until your stomach burns

and you want to throw up). And because your core is the center of power for most

other exercises, a long workout full of dynamic movements targeting legs, arms

and back also translates to a good core workout.

Of course, it won't matter how muscular your torso is if your body fat is too

high. The best way to build strong, visible abs isn't through repeated sit-ups,

but by engaging in circuit training that has you working your entire core while

you're burning calories – and to keep yourself disciplined during meals. " If you

want to burn your fat mass, make sure you have a combination of weight training

and cardiovascular, but 90 percent of good abs is your nutrition, " says Maresca.

However, he does offer a quick tip for those of us with a weakness for caloric

food: standing up straight and pulling back your shoulders will instantly

tighten your transverse abdominal muscle, making you look a little leaner. It's

not quite as impressive as showcasing a well-developed core via 10 percent body

fat, but it does leave a lot more time and flexibility for hitting up happy

hour.

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Sit-ups & Crunches to protect

the Back? Dr. Siff Says

" Not Really "

Even many physical therapists believe this advice, because it is maintained that

abdominal strength necessarily enhances trunk stability. While the abdominals

(recti abdominis) do contribute statically to trunk and pelvis stabilization

during many activities, it is contraction of the major back muscles (erector

spinae) which plays the dominant role in controlling erectness of the trunk.

The abdominal muscles statically resist the tendency of the abdomen to bulge

excessively when the Valsalva (breath-holding) manoeuvre is used during heavy

lifting, powerful stabilizing or pushing, and this is how they play a major role

in contributing to trunk stability and so-called " core strength. " They assist in

maintaining the pressure in the abdominal cavity to serve as a type of pneumatic

cushion or corset for the spine during lifting or heavy resistance work.

However, the strongest abdominals in the universe will not keep your back

'straight' during a heavy lift.

In fact, the more strongly your abdominals are pulled in, the less stable your

trunk can be during lifting, so, if you are lifting any serious loads, you would

be well advised to allow your body to do what it does naturally when it has to

stabilize itself under any large or sudden loading - and that is to hold breath

briefly and allow the abs to tense or distend slightly without any deliberate

attempt to change anything during any dynamic movement. This is what the world's

strongest weightlifters have been doing safely and powerfully for many decades,

so why not take a page out of the books of the world's finest practical experts?

The most important fact of all is that the abdominal and oblique muscles play no

dynamically active role in protecting the back, especially if one's breath is

not held. It is the deeper lying transversus muscle (which is not exercised by

sit-ups or crunches!) which contracts first in response to breath-holding and

straining during lifting and spinal extension. All of the other abdominal

muscles serve to flex the trunk forwards, not keep the trunk erect, so it is

illogical to believe that free-breathing abdominal exercise without adequate

back (and side) strengthening exercises enhances trunk stability and prevents

back pain or disability.

In other words, much of the advice that you hear on protecting your back by

executing more sit-ups or " pulling in " your abs, is often the opposite of what

you should be doing. To protect your back, you strengthen the muscles of the

back, not the front alone! Moreover, doing thousands of sit-ups or crunches will

do little to strengthen your abdominals after the first few weeks of novice

training. High repetition training with no progressive increase in load develops

muscle endurance and some muscle bulk, but not great amounts of strength.

Far greater abdominal strength is developed statically and quite incidentally by

automatic stabilizing actions taking place during many resistance training

exercises such as squats, cable press-downs, power cleans, bench press, all

forms of pressing and lat pull-downs. So, why on earth does everyone from

aerobics fans to footballers believe that high repetition unloaded sit-ups

really strengthen the abdominals? It is extremely rare to find anyone doing

several sets of sit-ups or crunches using heavy loads for a few repetitions, yet

this is precisely the type of training that one needs for developing abdominal

strength, as opposed to abdominal endurance under light loading.

Most of us have already learned one of the basic principles of all training,

namely that of Gradual Progressive Overload, which tells us if you wish to

increase strength, then you gradually need to increase the load that you are

training with. On the other hand, if you wish to increase muscle endurance, then

you will try to increase the number of reps that you are doing.

This criticism of sit-ups and crunches is not meant to imply that abdominal

strengthening is redundant. On the contrary, it is important to strengthen all

of the front, back and side trunk muscles so that none of them exhibits a

strength deficit during 'functional' or daily activities. More important than

that is learning the correct techniques of lifting or overcoming heavy loads,

since efficiency of movement and prevention of injury depends more on

correctness of technique than on strength of individual muscle groups alone.

If certain muscles of the trunk, such as transversus abdominis and erector

spinae, come into action in incorrect patterns or with inappropriate timing,

then even enormous strength of these muscles will not insure you against injury.

It is just that conventional high repetition sit-ups and crunches generally are

not very effective for developing strength of the abdominal musculature.

Not only are there superior ways of performing trunk flexion which really

strengthen 'the abs', but in any extensive resistance training workout involving

squats, tricep pushdowns, bent-arm pullovers, standing presses, cable crunches

and bench press, the abdominal muscles receive highly very adequate

strengthening, anyway.

Oh - and if you are doing sit-ups " to trim your waist " , you probably have

learned by now that spot reduction like that simply does not happen and that, if

anything, strenuous AB work tends to increase the size and muscularity of your

waist line. If you are doing crunches for definition " , then you have to realize

that " cutting up " any muscles of your body is far more a matter of eating wisely

and doing sufficiently demanding exercise of many muscle groups beside the abs.

(Article based upon a chapter in the book: Siff M C " Facts and Fallacies of

Fitness " 2000)

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Carruthers

Wakefield, UK