This might well be true due to over lengthening of the cross bridges. We already know that massage results in a decrease in strength, for memory both concentrically and eccentrically. What would be the readon to stretch between sets? If the strengthening exercises are full range (which they should be) then there is no need.

The other important this is that stretching can lead to injury if done between sets. I know that because I used to body build and one day after doing one body part I pay on a inversion table for 15mins before doing lateral pulldowns behind the neck (something I no longer recommend - infront is OK). Anyway I was then doing my first set of heavy pulldowns with writs straps to the bar and .... rupture .... either a rib joint or a lower thoracic disc. They had to carry me out of the gym into the massage room and support it so I could breath. The pain was incredible and even now, over 15 years later, I still have the pain during some rotation exercise.

Thus after this experience I never do any major stretching between sets. Basic stretching sure, but nothing particularly organised.

Maybe someone has some more specific research answers on this issue.