There is no single thing that will make a major difference but a total program is what you need. I would suggest a combination of power (lifting), explosion (plyometrics) , speed maintainance (over distance), and neuromuscular re-training (overspeed, one of my favorites), and finally starting technique and reaction time.
Look into speed programs such as Speed City, and Don Beebe's videos. This is the subject of entire books but let me just quickly tell you a few areas that have helped my athletes make significant improvement. Overspeed is one of my favorites because athletes get to feel what it's like to run faster. This can be accomplished using towing mechanisms and bungees, but I prefer running down a slightly sloping hill. I feel athletes maintain better form and don't fight the "tow" like they do with mechanisms. Also, you can accomplish alot more work in less time. Depth jumps and other plyos can be great but don't overdue it as they can devastate your performance especially in season. Don't do plyos more than once a week in season and never within 3 days of an important performance/game.
One of the most neglected muscle groups of major sports athletes is the
hip flexors. Look at world class sprinters and you will see phenomenal
hip flexor development. One simple lift for this is to stand against a wall with a 45 lb plate resting on one thigh. Lift the leg to 90 degree hip flexion and hold for a two count. Do this with relatively high reps 15-20 and don't do it fast or you will bounce the plate on your knee (not good). There is much,much more I could tell you but I don't have the time. There are many good books and videos.
Finally, if you want to improve your 100 time then run 200's. Also always run beyond the finish line, not to it. I can't help myself, I have to add one more thing. Most athletes don't consider the 100 to be a conditioning based event but the fact is that sprinters are no longer accelerating after about 40 meters, and are decelerating at about 80 meters. Proper conditioning as in overdistance and intervals will help you accelerate further down the track, maintain speed longer, and decelerate less. Many races are won not by the sprinter with the best top speed, but with the best maintainance of speed. Carl Lewis used to look like he grabbed an extra gear at about 60 meters when in reality he just maintained top speed better than others.
Linear Mode
