This study has been covered in HN before.

Is it really "typing" if you are only allowed to use your index finger?

I find it interesting that typing "requires" both hands to press keys while handwriting "requires" only a single hand to write (and the other hand typically just holds the paper steady).

I think it would be interesting to compare hand dominance in writing vs typing then.

it seems like these experiments are designed to generate a strong statistical effect? "data confirms old people forced to carry a 120lb weight run slower than unencumbered college track athletes!"