You need to have Rock Smash, first. Then, go to the tunnel in Verdanturf Town. Destroy the rocks where the guy and the girl are standing, and he will give you the HM for Strength.
You get the hm strength and give it to one of your pokemon
smash the rock inside the rusturf tunnel that is preventing the 2 people from each other
HM STRENGTH HM STRENGTH
HM 4
When you get to miavile in a house there is hm-Rock smash(beat Watson to use) then go to Vandturf, there will be a cave go in smash 1 boulder near the girl then the man comes accross and gives you hm-Strength
In Third Generation Whirlpool is no longer an HM.
you have to use strength, which is an hm you get.
In the Cave of Origin.
up your rump
you can get it in pokemon platinum!
HM 4 Strength can be obtained from one of the houses in Nimbasa.
you get hm strength and hm defog after defeating two gym leader.Fantina(defog) Byron(strength).