The fixator is one of many muscles used during situps. The fixator muscle stabilizes one part of your body when you move another part.
i think is the deltoid muscle but I'm not sure tbh
ur abs
Sit ups are an anaerobic exercise, which means that this type of exercise does not help in losing weight. Anaerobic exercises are used to build muscle and can actually cause an increase in weight because muscle weighs more than fat.
you can do lots of sit ups, it will strengthen your back and abdominal muscle!
Rectus abdominus Internal and external obliques Transversus abdominus.
Sit-ups will work out your abdominal muscles.
Steadily increase the amount and sit-ups and do multiple sets, or you could try other ab exercises with a medicine ball.
you can make your upper body more muscle by doing sit ups bench press push ups or any thing like that
Working out is the best answer, You should do 10 to 50 push ups a day and 10 to 20 sit ups every day.Hope that helped ???
Cardiac
The muscle that is primarily targeted and developed when doing sit-ups and tightening the abdominal wall is the rectus abdominis. This muscle is commonly referred to as the "abs" and is responsible for flexing the lumbar spine.
Leg lifts primarily target the lower abdominal muscles, while sit-ups engage both the upper and lower abdominal muscles. Sit-ups are generally more effective for overall abdominal muscle strengthening, while leg lifts are more focused on the lower abs.