Run-up and Speed up

Run-up noun - A substantial increase over a relatively short period of time.

Speed up and run-up are semantically related. In some cases you can use "Speed up" instead a verb phrase "Run-up".

Speed up verb - To cause to move or proceed fast or faster.

Run-up and speed up are semantically related. Sometimes you can replace phrase "Run-up" with "Speed up", this terms are similar.