When it comes to sprinting, the strongest athletes are always the fastest.
You can just take a look at the finals of the 100m from the last Olympics. The guys that were in that heat were all very muscular. You do not get that kind of muscle development from not lifting weights.
It might not be the priority of their training but it is a great supplement.
Athletes are no different. Those that want to be fast cannot be afraid to hit the weights. Combining speed with strength training is absolutely the best way to improve on speed.
I think it is too short sighted to claim that all athletes need is strength because it is the one thing that they are lacking most. What they really need is to get stronger and be able to use it in their game.
There are a lot of athletes that spend all of their time lifting and their speed suffers since they neglected it. There are also other athletes that neglect strength training and are still fast! Those athletes are naturally gifted and run with great technique. Give them some strength and they will only improve.
Athletes that lack speed are missing a couple of qualities. One is hip extension, or locking our the trail leg. If the hips and glutes are weak then they are not going to be able to propel the athlete forward.
The glutes are one of the most under trained muscle groups because of the amount of time we spend sitting. Prolonged sitting makes it difficult for the glutes to fire with any kind of real force. When an athlete can extend the trail leg with force, they have no choice but to become faster.
Athletes can also lack single leg stability in order to create a strong platform to run on. If the legs are weak they are not going to be able to hold steady when sprinting. Running can put a demand of up to 7x body weight on the legs. A strong and stable lower body, especially on one leg, makes for a great foundation to sprint off of.
If you had a superball and wanted to get the most bounce out of it, you would be much more successful throwing the ball off of concrete than a trampoline. Athletes that lack single leg strength are the trampoline.
Here are 4 exercises that are very helpful in creating strength to benefit sprinting.
Hex Bar Deadlift
This is by far my favorite exercise for building posterior chain strength. Standing up with the hex bar trains hip extension. When athletes can make progress with the hex bar deadlift, their sprinting benefits tremendously. It also teaches total body stability which is needed for good sprinting technique.
The KB swing is a very similar pattern to the hex bar deadlift. The only thing that changes is the speed at which the movement occurs. The KB swing is a more violent exercises which requires more power and control. the key to success is being able to move the kettlebell quickly, while maintaining good technique. A simple video search will probably result in some terrible KB swings. Proper KB swings will teach the athlete how to extend their hips, rapidly.
Step Ups train single leg stability and hip extension. This is a 2 for one movement with the only downside being that it is not as much of a strength movement as a lunge.
Grabbing two heavy weights in each hand and stepping up to the box with a lockout on that leg can be very difficult. It will strengthen the pattern required for fast sprinting.
Bulgarian Split Squats
This is by far the hardest single leg exercise that I use with my athletes. The strength required in the lower body is very high. That also means that it is going to benefit sprinting greatly.
When we run we want to be like a spring. Using this exercise will build the concrete on which to bounce off of.
Athletes that do not take their strength training seriously are really missing out on an opportunity to improve. Spending time on the turf to put it together is also important. The key to this is that strength is needed to sprint fast and there is no way around it.