Push-up – Upper body. The push-up targets the chest, shoulders, and the triceps. This exercise also engages unexpected muscles from the abdominal core to the lower back as well.
Sit-up – Abdominal area. They target the hip flexors, rectus abdominus, iliopsoas, tensor fasciae latae, rectus femoris, Sartorius, and to a very small degree, the oblique’s.
Pull-up – Upper body. There is no other exercise that will make your upper body grow quite like pull-ups. They target the back and biceps.