How to strengthen abdominal muscles?

Q: I have been operated twice for hernia, once 5 years back and then last year again. Both sides are operated. I want to do some yoga. Can I do Vajraasan? Kindly guide me what posture/exercise I should avoid?

A:Your abdominal muscles must be very weak. Try and strengthen your abdominal muscles in standing position. Avoid doing exercises that increase the intra- abdominal pressure. Avoid doing sit-ups with weights behind the neck. Exercises performed upside down are always best. In standing position, when you do the exercises, breathe in as you come down, and breathe out as you raise your stomach.- Lose excess weight.- Do not lift heavy weights.- Be gentle with your spinal twists- Avoid all slouching postures.- Use good body mechanics for lifting and working.- Walking and swimming would be the best things to do.- You can do your asana with a halt where you feel the stretch.