Quite silly you have to hold it in the air with both hands:
"hold it" = strain on the fingers because the hands cannot change their position relative to the keyboard,
"in the air" = strain on the arms because they are permanently raised,
"with both hands" = doing anything else than typing (e.g. taking a sip of a drink) requires putting that thing down. If you hold it with only one hand, you have to grip it firmly but at the same time be careful not to hit any key.
Nice thing for a typing competition, but not for normal use.