That was in Running with the Legends. Track and field News Sept or Oct maybe Nov 76 had a piece on Viren.
Lasse kicks off his training in November after a month of active rest. This basic conditioning period lasts until April, when he begins a month of hill work and strength training. Then from June until September he does competitive season training.
During the basic conditioning phase, Viren will run three times a day, covering 22 - 30 miles, with the longest run about 13.5 miles. Should he only run once or twice a day , his longest effort could be over 22 miles. Training venues are changed regularly to head off boredom.
As summer approaches, the percentage of long work is decreased and hill running instituted. As he does no weight training, Viren's strength comes from these repetitions up an 800 meter hill.
During the racing season, races are sometimes used as supplemental speed work to sessions of fartlek. long/easy running is retained, however, and his long runs will reach 25 - 30 miles