Mills and Bolt may not talk about being explosive from the blocks but he is most certainly explosive as hell from the blocks.
I also believe that he lifts mainly in the 8-12 range on machine type lifts as much as he does barbells. Like hack squat machine and hammer strength bench and stuff. There are some photos of him in a hack squat setup, videos of him doing curls and machine bench. I posted a video of him doing close grip barbell bench in Paris with about 155 repping pretty fast. From discussing and asking questions to Jamaicans and coaches who have had athletes train with Mills the weights are geared toward general strengthening and injury prevention.