^ Thinking of the way Klingons fought humans in TOS Trouble with Tribbles and DS9 Way of the Warrior. Im inclined to reevaluate my earlier estimate of klingons = 2x human strength. Klingons may be 1 to 1 for humans or possess the potential to surpass human strength levels in they engage in regular strength training exercise.
Also the Romulans in ST09 were all miners. That could accommodate for their increased strength. Since Romulans from TOS-TNG-DS9-ENT were never shown to be physically superior to humans.