acclimation

By definition, acclimation is “the process in which an individual organism adjusts to a change in its environment (such as altitude, temperature, humidity, photoperiod, or pH), allowing it to maintain performance across a range of environmental conditions.”

Does “allowing it to maintain performance across a range of environmental conditions” mean getting to a place where one can positively maintain performance? Or does it mean simplymaintaining under the set of conditions, even if at a low-level?