I am not saying this is scientifically proven, but the arm movment required to play football in VR is not only fun but energetic too. The motion of moving your arm back and forth with the added weight of the controller has significantly helped tone my arms.
I notice that after playing my heart rate is increased, and I am hot a sweaty, the useual after expercise effects I miss feeling due to sheer lazyness, but some how it doesn't feel like a chore, its fun! I'll keep you updated on my progress soon.