The following two links provide an insight into the training of Alberto Juantorena - 1976 Olympic Games Gold Medallist in the 400 m and 800 m.
Specific Training for the 400 - 800m runner
An insight into Juantorena's general preparation training
Juantorena used the periodization method, brought to Cuba by Zabierzowski and foreign coaches after the revolution. What Juantorena calls his "General Training", from October through February, was designed to build up his overall stamina. He says the training was tough. "We used to train on sand hills, two times day, up to 25 kilometers a day; 15 km in morning, 10 km in evening."
After several months of this stamina work , Juantorena began specific training.
Source Running With Legends