Pitcher throwing ball
If you're into sports, you've likely heard the term "short-arming the ball."  If not, what it means is not using a full extension of your arm when you are making a pitch, throwing a football etc.  The reason athletes want to avoid "short-arming" the ball is that it causes a loss in distance and velocity.  It's less effective.  Coaches will work with those athletes to help them get more extension and a greater range of motion in their throwing attempts, so they attain more speed and accuracy. 

There's an equivalent to short-arming when it comes to chivalry.  For some guys there's a degree of uncertainty.  Do they really want to do it?  Does she really want it?  Do I look too formal or out-of-place?  What ends up happening for some men is that they pull back and offer something that looks chivalrous but isn't fully extended.  That results in a gesture that looks awkward or not elegant, and it renders the act less effective.