Newly-appointed offensive coordinator Norv Turner has begun influencing the Vikings setup, and Jennings has stated that it is a lot more difficult that the 'West Coast' offence that he is accustomed to.
On Wednesday, Jennings told reporters: "My head is spinning, even though the offense is coming, and it's starting to sink in.
"The different formations that we can run with the same play, different variations that comes with the same play, your head is spinning at all times.
"If last year's offense was complicated, guys will struggle with this one, for sure."
Jennings recorded 68 receptions for 804 yards last season, scoring four touchdowns.