The V-Sit is a great exercise for developing your lumbar spine stability and ab strength. This simple yet effective static hold uses a medicine ball as additional resistance. This isometric exercise turns into an ab blaster, perfect for increasing your core stabilizer strength endurance. This is a 15 rep set exercise demonstration. This exercise is part of a full length workout video from the mypypeline.com intermediate fitness program, CTX Cross Training Extreme Series, Volume 3, Session 12.