Adding the same header row to multiple spreadsheets

Hello everyone

I have several data files (each in XLS format) that are the output of an experiment. Unfortunately, the files were created (in Matlab) without header rows, so it's hard to keep track of what each of the 10+ columns mean. I would therefore like to add a header row (the same header row) to each one of these spreadsheets, but I cannot figure out a way to do this automatically. I have hundreds of data files, and opening each one of them, pasting the header row and saving would take a lot of time.

Can anyone suggest a way to do this? Anticipated thanks for any replies!

Also, I really need to be able to do this quite soon, therefore apologies for cross-posting this on another Excel forum as well (will mark both as solved when they are)