Now featuring movie demos!
Frequently Asked Questions
Why are crunches better/safer than situps?
Crunches focus your effort solely on the abdominal muscles, while Sit-Ups involve both the abdominals and the hip flexors (ilio psoas). The purpose of the rectus abdominis (the primary abdominal muscle group) is to bring your sternum closer to your pelvis. This only involves the first 30 degrees of movement from the horizontal position. Anything beyond that engages your hip flexors. The psoas (as their frequently called) attach at the front and top of the thigh, and wrap around to connect at the base of your spine. Whenever you perform a movement where you're bringing your thigh closer to your torso, you use your psoas. So, if the upper part of your thighs has ever felt sore during Sit-Ups, that's why.
From an injury stand point, Sit-Ups tend to grind the vertebrae in the lower part of the spine. This can aggravate sensitive lower backs. Since we're focusing on the abdominals rather than our hip flexors anyway, why not avoid potential lower back injury and just do crunches. Crunches are more fun anyway.
Where can I do this exercise?
Find a clear spot on the floor at your gym, perhaps in the aerobics room if it's empty, or anywhere you can have uncluttered access to the floor. You can even do this exercise at home.
Music? Yes or No?
Crunching to music is preferable. I find it makes the time pass faster, and it can be motivational sometimes. Depends on the music you like. I usually use dance music that has a ~105 beat per minute count to it. But any music with 32 count phrasing will do. The most important part is that you want it to be rythmic and relatively slow.
Speed & duration of the workout?
It should take you around 3 seconds to do a complete crunch (1.5 seconds up, 1.5 seconds back). Go for about 5-10 minutes to start. Next time you do them (2 days later), go for 15 minutes. I usually do abs 3 days a week.
What about my lower back?
This exercise is done using a limited range of motion with no momentum, therefore your lower back should be safe. However, there are a few things you should be aware of so that you avoid any unintentional injury.
AVOID UNSUPPORTED SPINAL FLEXION.
Whenever you're lying down and both your legs are extended outward, your spine has to bend upward to compensate for the change in your body's center of gravity. This can aggravate sensitive lower backs. The first picture to the left demonstrates this position.
The best way to keep this from happening is to:
either keep both your thighs parallel to the wall (so that your knees are directly above your hips) , like when doing the reverse crunch,
or have one foot on the floor when the other leg is extended. This helps distribute your body weight over a larger surface area and takes the strain off your lower back. The 2nd picture on the left demonstrates this.
How does the exercise work?
This exercise trains the abdominal muscles by groups. The rectus abdominis brings the sternum toward the pelvis. The transverse obliques and external obliques allow the torso to twist. Lastly the serratus anterior line the ribcage and are indirectly trained as stablizing muscles.
We start with the upper portion of the rectus abdominis, then move to the lower. The third phase of the routine involves the obliques and serratus anterior.
For counting purposes, you'll want to do sets of 8 (eight). In this routine we vary the speed and direction of your crunch, thus targeting the different abdominal regions.
In regards to speed and range of motion, here's the terminology we'll use:
Click on the link below to see a movie demonstration of the movement (.WMV)
SINGLE counts, (up in one beat, back in one beat),
DOUBLE(up in 2 beats, back in 2 beats),
3:1 (TRIPLE) counts (up in 3 beats, back in 1), or
PULSES (contracting and releasing repeatedly at the top of the movement for a count of 16). Pulsing really burns, so you'll want to add some variety to it; (perhaps do 4 singles, and 8 pulses).
DOUBLE HOLD crunch (up and hold for 2 beats, back in 2 beats),
TRIPLE HOLD crunch (up and hold for 3 beats, back in 1)