Training Question??

I just got back into masters after 8 years. I trained three times a week for a meet and did ok but was hurting at the end of 100's and now I feel like if I don't hit it 6 times a week I will not see much of an improvement if I don't hit it hard. I'm a sprinter and need some suggestions of how much should I be training and what's too much if this makes any sense??? Josh H