The V-up is an ab and hip flexor exercise that can be considered an advanced variation of the jack knife
Lie on the floor with the legs extended straight and your arms extended overhead. Simultaneously perform a sit-up with the trunk and lift your legs with straight knees, reaching the hands up to touch the toes as you create a V shape with the body. Your balance should be such that you can pause when the hands and feet meet and hold this position. Return to an extended body position without allowing the heels to touch the floor in between reps.
The V-up trains both strength and stamina of the ab and hip flexors, and provides a more challenging variation of the sit-up and jack knife.
The V-up should be performed for sets of 10-30+ and will generally be more of a stamina exercise with higher reps.
The V-up can be performed by bending the knees and with the hands on the head, bringing the knees and elbows together, making the exercise a jack knife
Hanging leg raise