Actually, that's not true. Inventions and innovations in technology were occuring all throughout this period in Western Europe and Italy (Renaissance?). Similar improvements didn't occur in the Islamic world even at this time. Mathematicians were just about the only group that could do anything since their work was theoretical and less likely to trip over religious restrictions (and even this group was tiny when compared to the West). Most innovations seen in the Islamic world came about through the importation of Westerners, free and slaves. But such innovations didn't get passed on and improved on through the generations. Instead, Islamic customs and laws choked out the chances of improvement and the possibility of cross-fertilization of ideas.
Think about it. During this period, the West launched Crusades that attacked the heart of Arab strength. These Crusades were launched by sea across great distances, generally using surplus nobles and forces. They were only beaten back the rise of the Turks, a newly converted people (i.e. not yet stagnant under Islam) and after many years.
Islam, despite it's seemingly greater strength, was unable to launch similar naval conquests into Italy or Southern France. Why? Because Islam is inherently antithecal to progress itself. It can never be more than a parasite on neighboring cultures. Left to it's own devices, it would return humanity to a Bronze Age culture.
As an aside, this professor made the point that Christendom had it's reformation but that Islam had not. He opined that it was long past due.