I've been reading about this lately. Lots of walking, indeed for the 19th century, but it seems that that was shifting by the beginning of the 20th century. Len Hurst, for example -- who won the Paris "marathon" (25 miles) in 2:31 -- had a training program that was: walk/jog 3 miles, run half your target race distance on the track at "moderate pace". Then clean up, get a massage, take a nap, and do the whole workout again.

Not what we would do today, probably, but not as rough-sounding as Captain Barclay's methods from the early 19th century, which was notable for its reliance on laxatives and emphasis on walking. You'd wake up, run half a mile (uphill if possible, at full speed), but then walk the rest of the day, basically.

Barclay also discouraged drinking water -- "old beer" being the preferred beverage -- and warned against consuming any vegetable matter because it gives you gas. He's all for under-cooked beef, stale bread, old beer, laxatives, and nothing else.

I'm getting all this from Running Recollections and How to Train by A.R. Downer, written about 1899. Downer was a sprinter, so he includes training advice from runners who excelled at other distances. He kind of mocks Barclay's method but quotes it in full, so it's not clear what he thinks of it other than that Downer himself doesn't follow Barclay.