Kiteboarding can be as physically exerting as walking to your neighbours house or as tiring as running up Machu Piccu, it depends how you ride. Since almost all of the kites power is transferred through your waist harness your arms will not be sore after a ride but it is rather your legs which would be feeling some burn if any after your session if you have not been on a board recently.
Kiteboarding is an independent sport, we will train you to be able to ride how you would like too.