Weights can make you feel faster. (and power out of the blocks just a litle quicker than before) - during the first phase of a weightlifitng/powerlifting cycle.
This is because your nervous system has learned to recruit more fibers. (hence more power and the ‘feeling’ of more acceleration. But that acceleration speed is only fractionaly quicker, and not quite correlating to the ‘feeling’ much better in acceleration.)
After several of those ‘New’ or upgraded sessions, your nervous system learns to recruit LESS fibers to get the same job done. In both the weight training exercises, and the sprints and any other exercise. So the nervous sytem is trying to return to its happy medium of power outputt, whilst your training is trying to trick your nervous system in to higher power outputt.
After several cycles (much less time for some experianced athletes) you’re not feeling or apreciating the power feeling in acceleration so much, because you are used to it. And…
When you run a 100m, you are learning to pace the power envelope over 9 to 12 seconds, and so you try to accelerate smoothly, so you’ve still got something in the tank between the critical 50m & 80m lines. This is top-end speed for a decent sprinter.
Heavy olympic weightlifitng does not resemble the smooth transition you need in a 100m. It only resembles the jump out of the starting blocks.
So you might leave the starting blocks with higher energy & velocity, putting you in to the next stride at a fractionally higher speed and sooner. But from there, it is all over. Your energy envelope is having to spread itself, and may even be slightly compromised later in the race.
To say weightlifting improoves acceleration speed is a generous statement. It doesn’t improove every ones acceleration speed. Weightlifter may be at 20.5 m line whilst twin brother is at 20m line, but twin brother is moving at same velocity by that point. (In which case, non-weightlifting twin brother, reached same velocity at the same 20m point as weightlifter. Weightlifter is burning up his revs, but twin brother still has more energy left and is looking forward to higher top end speed. This is because non-weightlifting twin brother has spent more time training on the track, doing running, tempo, strides, sprints, hopping and hops with med ball etc… Big open space.)
There is only going to be one winner at the 100m finish line. And 9 times out of 10, it’s the guy who recorded the highest top-end speed, even if it is only experianced for 1 to 2.5 seconds.
And that’s just a pre-season time trial. Twin brother hasn’t even began the ‘sharpners’ yet.
So now twin brother starts doing block start practice, a couple of sled pulls, may be a few cone drills (i dont think they are necesary for all sprinters).
The competition phase begins, and ‘twin’ now atleast matches weightlifter out of the blocks, gets ahead at 25m, and gets well ahead by 70m.