Interesting. It might be worth separating creatine and caffeine intake. I never heard this before.
Supplementation with either creatine or caffeine has consistently been shown to enhance high-intensity exercise performance in most people, and the ingredients are thought to achieve this feat via separate physiological mechanisms. There also doesn’t appear to be any pharmacokinetic interactions when caffeine or creatine are taken together; i.e., neither caffeine nor creatine affects the other’s blood levels.[1] Caffeine does not influence creatine’s ability to increase muscle phosphocreatine storage[2], which makes combined supplementation of creatine and caffeine an attractive prospect for athletes and recreational exercisers alike.
However, there is some evidence to suggest that chronic caffeine consumption during creatine loading blunts the ergogenic (i.e., performance-enhancing) effect of creatine.