Training your abs every day is a very bad idea. The abs are a thin layer of small muscles that need recovery time just
like any other muscle. They are used for many body movements and exercises, such as squatting and dead lift, so
continually breaking the muscle fibers of these is counterproductive. To get the most out of each workout, train your
abs intensely 1 or 2 times a week just like any other muscle group.
To answer your question about doing push-ups and crunches each and every day: Go for it. The only time you ever need to skip a day before you can do the same exercise is when the weight is so great that you have created the conditions for overload and muscular hypertrophy. The body needs 36 hours to recover from that sort of exertion. Lifting the weight any sooner wouldn’t hurt you but it also wouldn’t help youit would likely only delay the benefit of the earlier workout.
If you possess a basic level of strength, however, a push-up doesn’t really fall into that category. Up until 20 or reps, a push-up is more of a muscle-toning than muscle-building exercise. And after 20 reps it becomes primarily a test of local muscle endurance (which may be one reason why the results of old-school push-up tests used by the military and the government tend to not correlate with overall fitness statistics).
Sit-ups and Take Note: Don’t overwork your abs!
How many times have you heard “sit-ups are different, just keep going” from a trainer? This article explores – and refutes – that advice. We explore the sit-up and the abdominal muscles in relation to the other muscles in your body.
There are a lot of misconceptions out there about fitness in general. One that seems to be very prevalent is the idea that your abdominal muscles are somehow different from the rest of the muscles in your body. You can see this tendency whenever someone asks “how many sit-ups do I need to do every day?” or “how many crunches do I do to have a flat stomach?” These questions stem from the idea that your abs are different from the rest of your body.
Think about it for a second. You don’t really hear stuff like that about the other muscles, even the ones that are the most popular for aesthetics. Chest, arms, butt, whatever else is a sex symbol on male or female, they don’t get slotted into the same category as abs. Abs are special…
…but are they? No, not really. They have a unique shape, that’s true, and they perform some very specific functions for the body (moving the ribs, etc.) but they aren’t inherently special, physiologically speaking.
What’s the Problem?
The Abdominals are skeletal muscles, just like your quadriceps, triceps, and trapezius. This means that they connect to bone, and you can control them to a large extent. Skeletal muscles are capable of voluntary contractions, unlike smooth muscles (stomach muscle, for instance) which are autonomic.
Side Bar: Autonomic muscles are controlled by the brain and nervous system working on auto-pilot. They contract based on management processes in the body which respond to different stimuli. For instance your actual stomach muscle responds to ingesting food or liquid by turning on digestive actions, whereas your abdominal muscles are most often responding to a voluntary contraction like sit-ups.
The abs, being able to voluntarily contract, can also be trained like all the other skeletal muscles. Much like a push-up or a squat, you contract the abs against resistance (sit-ups or toe-ups) and/or for longer periods of time than normal (planks) and their strength builds. If you work them too hard or too often, they can suffer from over-training, just like the other skeletal muscles.
That’s the first thing that seems to cause confusion: some people think you can train your abs every day at high intensity without issue. This is not only false, but dangerous. If you try to do 300 sit-ups every day, you’re a lot more likely to get rhabdomyolysis than a six-pack.