Spawn Adjust

I'm looking to make it so that when a given team (in this case, Red) is in danger of having their last capture point taken, they respawn slightly faster. I get the impression that I'd do that in the trigger_capture_area where it says:

Red spawn adjust
Blue spawn adjust

Now typically, I have left both of these values at zero and each team simply respawns at the default rate. But if I were to adjust these, how would I do it? What would the numbers mean? I worry that making the numbers any greater than zero would simply make it take longer to respawn.

And if this isn't the best way to decrease Red's spawn time, is there a better one?

Thanks for explaining that. I guess I'll need to do something creative so that the shortened spawntime doesn't affect the Red team until they're on their last point, even though they own that point the entire time.