I don't have a very rigid plan. I do what I feel like doing nowadays. I just slapped stuff together from misc. research; it's not vetted. Here's an unordered list of things I do over a few weeks:
- A lot of joint and tendon work. Most of your explosiveness comes from your tendons.
- I do a bit of weight training (loaded carries, power pulls).
- Long-ish (say, quarter) repeats with slow jogs or walks inbetween. General fitness.
- Extremely slow jogging, 2 to 4 miles. General health and fitness.
- Lower-impact variations of sprinting, e.g., hill sprints (which also puts me in my drive phase).
- Cross-training, like sprint intervals on the erg rower.
- Plyometrics: a lot of hopping and jumping.
- Mobility drills and stretching.
- Body-weight exercises: pull ups, push ups, pistol squats, a lot of dead hangs
Sprinting isn't an old man's game, but I reckon it's good for you.