The v-up is a fairly advanced abdominal exercise, which involves the simultaneous flexion of the hip and spine to target the rectus abdominis (a.k.a. the “six-pack”), obliques, and the hip flexors. The exercise requires some level of abdominal strength, so it may not be a suitable choice for a beginner who will likely find the traditional crunch a better starting point.
Some state that the raising of the legs from the ground targets the lower portion of the abdominals, while the raising of the shoulders and head targets the upper portion, yet this is not entirely true. The raising of the legs is primarily performed by the hip flexor muscles, not the abdominals. Gym-goers may mistake fatigue of hip flexor muscles as being that of the lower abdomen. The abdominals will come into play, with regards to the leg raise, at the top of the exercise, if the athlete raises their hips off the ground, thus shortening the distance between the pelvis and the ribcage.