Aerobic workout...
Tickling can be an aerobic workout, if you go medium on the ticklee.
If you go slow and gentle they won't work up a sweat and if you tickle hard and fast you will they will tire quickly.
But if you tickle at a medium rate, your ticklee can be laughing of the pounds.
Tickling to the oldies...
Actually for a real workout, use light but effective bondage on your ticklee. Say keep the armpits loose but open and they will bounce around, squirm, wiggle and...work up a sweat.
Or for some great crunches, tie up just thier feet and so they can barely block the tickling and they will be crunching just to stay crunched...
Tickling can be a great workout if done right. My wife lost 20 lbs from tickling, I kid you NOT!!!!!