Is it healthy to do 160 sit ups in 10 minutes?

Is it healthy? I am currently training for children in need where i will be doing 200 sit-ups in 3 minutes, i can currently do 176 after 2 days of serious training. but it all depends on the age of the person and stamina, as i am young i would find it easier than a middle aged person. Thats not to say its not easy!! :D thanks