What is the use of futile reaction cycling such as Fruc-P to Fruc-BP?
As far as I am aware there are various regulatory mechanisms (allosteric regulation, hormonal control) in place to minimise futile cycling by ensuring that phosphofructokinase (glycolysis) and fructose 1,6 bisphosphatase (gluconeogenesis) are not both active at the same time.

See this Wikipedia article for a starting point.


  The precise regulation of PFK1 prevents glycolysis and gluconeogenesis from occurring simultaneously. However, there is substrate cycling between F6P and F-1,6-BP. Fructose-1,6-bisphosphatase (FBPase) catalyzes the hydrolysis of F-1,6-BP back to F6P, the reverse reaction catalyzed by PFK1. There is a small amount of FBPase activity during glycolysis and some PFK1 activity during gluconeogenesis. This cycle allows for the amplification of metabolic signals as well as the generation of heat by ATP hydrolysis.


The last two sentences of the quotation are probably what you remember reading about. There is a theory that having some cycling provides an element of regulatory responsiveness. See here for example. I'm not enough of a mathematician to explain this idea well.