Muscle tissue does not differ scientifically between males and females. Both men and women can train exactly the same way, and what many females don't realize is the 'toned' look they are after is gained through the proper balance of muscle size and % body fat. Therefore, to increase muscle size weight increments must increase and reps should be limited to less than 10. Another benefit of increasing your muscle size is that it costs your body more calories to sustain the new muscular tissue, thus making your body a fat burning machine even while resting. Also, ladies, do not worry about becoming too bulky. It is impossible since females lack the necessary amount of testosterone found in their male counterparts. Muscular growth only occurs within a normal range for your body.
Sit ups - The ultimate abdominal exercise
Sit ups have long been hailed as the be all, end all way to achieve that killer mid-section. However, just like our lesson from above they are often performed with too light of weight for too many reps. Repeatedly contorting ones back in such a way can lead to many posture imbalances including kyphosis. (think hunch backed person walking with a cane). Also, repeatedly flexing the torso toward the hips mostly involves the hip flexors and very little of the abdominal musculature. In many cases, tight hip flexors are the major cause of chronic lower back pain. Tight hip flexors can also cause the pelvis to tilt forward farther than usual increasing the strain on the vertebrae in the lower back (a condition known as lordosis) a real doozy for the lower back, and think all of this from a movement meant to "help" your core.
This hydra will kill you if you do another sit up
There is one type of training that is superior to another