Is it better to start fast and taper at the end of a timed 1.5 mile run? Or start off slow and finish strong?

start slow and finish strong

it is only 1.5 miles, how hard can it be to go all-out?

try that tactic on a 15-mile run.

What I have done based on experience and also read too is that you should start slow. Then gradually work your way into your normal running pace. Then you can go faster from there. If you saw go too fast to begin, you are going to poop out eventually. I know I know the rush is there and you just want to fly like the dust,but don't. Remind yourself of the tortoise and the hair....tortoise the slower finished first.

Start conservatively and then give it all you've got at the end. A lot of times you'll have more "umph" at the end with the desire to cross that finish line, whereas if you use all your energy up in the beginning, you may not have enough left for a strong finish.

Your odds are higher to have the better time if you start off easy and then kick it into overdrive later, than if you go out quickly and tire.

Of those choices, I would say start off slowly, and finish strong.

But, there is a choice better than those two: Do a good warm up. And then hold a consistent pace through the 1.5 miles. Ideally, the pace would be one that just barely allows you to reach the finish line.

That assumes the course is consistent. If there are hill or other challenges, you would go by consistent effort instead of pace.

By the way, whatever your plan, you should do a good warm up. Neither the "start strong" plan nor the "consistent pace" plan will work unless you are already warmed up at the starting line.

Without a warm up, you could do the run by starting slowly and gradually pick up speed. But, without a warmup, your time will be slower than you would have gotten with a warmup.