Sprinting/Athletics

Squats, deadlifts, and box jumps, or many other forms of plyometric training / circuits.  You want the types with explosive movements.  Just make sure you're really well warmed up before attempting any of those exercises and most importantly get advise from a professional on how to do them properly to avoid injury.

Craigerrs, what do you already do?

Ratzer: I do lots of sets which is mainly jog, sprint, jog, sprint etc. But I think I need to do more as my competition is getting bigger and harder. 

Paul J-R: I will try the squats and deadlifts. How many do you think I should do in one set?

Find a really steep hill. Warm up well. Sprint for no more than 5 seconds almost full out. Recover for 15 minutes. twice more, no more. Don't want to develope endurance, slows you down.

Craigerrs - do you use a gym?  You'll need help from a qualified gym instructor to show you the proper form, to make sure you avoid injury.  I tend to do 4 sets of 12 reps, but you can do 15, upping the weight a bit on the final 2 sets.  The final set I might only do about 8 reps if I increase the weight more.  The last few reps of the final set should be really hard.

Although for 100m training, it might be better to do only 3 sets of 8 reps, so you train for strength rather than endurance.

Do a Google search Usian Bolt 100m training...I found the squidoo link below that has his training plan:

I did initially paste the info but I thought 'copyright!!' so best look yourself or use the link below:

Source: http://www.squidoo.com/usain-bolt-workout