When I was 8, 9, 10, 11, etc., my father knew well a Kung Fu instructor, Leonard Lim, then ranked 6th in the Tai Mantis style in the early 1970s and based in Oakland, Calif. He was pretty good friends with Bruce Lee who also spent some years there.
Mr. Lim knew I had gotten into running as the decades went by and how highly I had always regarded Bruce Lee's fitness level. Mr. Lim said Bruce Lee ran 4-10 miles a day along with his extensive martial arts training (4-7 hours a day!), and though Lee could run 10 miles in about 55 minutes, it was a pretty supreme effort. Not too shabby by any stretch and I'm sure Bruce Lee could have been much faster with more specific training.
Not sure I give much credence to the statement that he dabbled in steroids though. Bruce Lee was staunchly against any drugs, even cough medicine.
A couple of Bruce Lee's stats: Height tad over 5-7, weight 135-140. Lee had a punch strength of 300 lbs. (Mohammed Ali's was 280 lbs.). They had to slow his routines down in order for his movements to be seen on film when he shot certain scenes in movies, they didn't make film fast enough to capture his fight sequences at full speed.