Gabe Mirkin, M.D.
In 1900, the world record for the mile was 4 minutes and 15 seconds. 35 years later, it was 8 seconds faster, and now, 100 years later, it is almost 35 seconds faster.
The fantastic improvement in world records is due to superior training methods. The limiting factor in running long distances very fast is percent VO2 max, or the maximum amount of oxygen you can take in and use. Don Lash, the world record holder in 1935, had the same VO2max as the best runners today and he ran only 4 minutes and 7 seconds, 26 seconds slower than the present record.
Today's runners run the entire race near their VO2max because they run so much faster in training. A runner can run the entire marathon at more than 80 percent of his VO2 max, because he runs so much faster in training. Fifty years ago, the best marathon runners ran their very fast interval workouts at a pace of no faster than 4 minutes and 20 seconds per mile with repeat quarter miles at 65 seconds. Now, virtually all top marathon runners run their repeat quarter miles faster than 60 seconds each. It's the faster training, even at the expense of a reduced workout and longer recovery periods, that makes the difference.