Wiki said "The sit-up is an abdominal strength training exercise commonly performed to strengthen the abdominal muscles. It is similar to a crunch (crunches target the rectus abdominus and also work the obliques), but sit-ups have a fuller range of motion and condition additional muscles. Sit-ups target the hip flexors, rectus abdominus and also work the iliopsoas, tensor fasciae latae, rectus femoris, sartorius, and, to a very small degree, the obliques"
Classic Sit Up
- Doing sit-ups badly lessens their benefit and can result in terrible back problems. The main mistake that everyone makes is using their hands for leverage.
- All the hands should do is keep the head still and in place. Using hands for leverage puts strain on the vetebrae in the neck and all the way along the spine.
- Furthermore, the emphasis of the movement is taken away from the abdominals, which lessens the intensity of the exercise overall.
- Sit-ups should not be done with straight legs because if the knees are not flexed too much pressure is put on the base of the spine.
- In addition, the hip flexors start doing all the muscular work, which can result in a pot belly.
- A useful warning is that if when doing sit-ups any muscles other than the abdominals start to ache, then you should stop and reassess your technique.
- The contraction should always be the requisite 30 degrees, but never more. Beyond the 30 degrees other muscles come into play and start doing the work.
- Often people find when they do a sit-up is that the initial lift hurts, but then the exercise becomes far easier, this is simply because the stomach muscles are not being used any more (Dailymail)
Crisscross sit up
- Crisscross known as the bicycle
- This exercise initially isolates your abdominals by lifting your knees and shoulders off the ground.
- Be carefull not to pull on your neck
- Crossover crunch targets the abdominal and oblique muscles, as well as the muscles in the lower back.
- Effective in strengthening abdominal and oblique muscles, but can also aid in the treatment and prevention of lower back pain.
- Flutter kicks, levers, and scissors are staple ab exercises in the workouts of military special operators.
- Avoid these exercises if you have low back problems.
- Flutter kicks are a four-count exercise and intensely work your abs and hip flexors