It says in Shulchan Aruch that one may not lean on anything while reciting sh'mona esre. (OC 94:8) The Mishna B'rura defines "leaning" as placing one's weight on another object such that if the object were removed the person would fall over. (ibid. 22) How is this definition to be understood? If a person places almost any amount of weight on an object without exerting any other force on it, he has necessarily shifted his center of mass to a point closer to the object than it was when he was free-standing. Should the object be removed and the person not compensate by shifting his center of mass back, he will fall over. Could it be that even the slightest of "leanings" fits the Mishna B'rura's definition?
Alternatively, if we allow for shifting of mass following the object's removal, then how do we understand the basics of the definition? I could be leaning to an extreme angle and still catch myself by proper placement of an arm, a leg or a torso.
Is there a middle ground? I have always had trouble with this concept and have never received a satisfying explanation.