weights, speed

if your aim it to have a quicker start, would it be better to lift weights quickly with a lighter weight, or just focus on heavy lifts or a different approch altogether?

Even if you lighten the load to 50% of your 1rm max - its still so much slower than a Block start its not even in the same ball park of speed.

yes quite right… but to supplement the track work, what would be better? i am wondering because i often find that if i lift heavy my legs are pretty wrecked for a while, but if i drop it to 50% and work on speed i feel less fatigued

Block clearance is not the same thing as acceleration power, and there is not one “magic bullet.”

If you do a literature search you will find research showing that heavy weights work mostly in the first 10 meters–and you will find some threads here talking about powerlifters and even shotputters beating sprinters for the first 10 meters…and then the sprinters kill them. But there is work showing that short track work (as short as 10-20m) works about as well as heavy weights, but by a different mechanism. Going out to 30 meters, the best strength exercise is countermovement jumps.

What you really need is a combination of approaches, properly sequenced.