In running the marathon at a constant hard pace, Snell ran to the limits of his slow
twitch fiber capacity and then exhausted the glycogen stores in his fast twitch fibers to
the point where he had to sit down. He recovered his glycogen reserves slowly over a
week and the training effect was to force some fast twitch fibers to adapt. They were
now quite possibly acting as type IIa fast twitch fibers, with aerobic endurance
characteristics as well as a very large anaerobic glycolytic potential.
This potential, of course, couldn’t be realized until a variety of hard fast workouts and
races capitalized on their emergence. The rest is history, and we can learn from history.
While most modern coaches wouldn’t recommend a full marathon so close to track
racing, at least one great coach of the 1970s was paying attention. John Walker ran for
over 20 miles at the head of New Zealand’s tough Rotorua marathon in April 1975.
Then he jogged off the track, with his mission accomplished, amidst quite a few ruffled
marathoners’ feathers. Why?
A couple of months later he was the first man to smash the 3.50 mile barrier. His coach,
Arch Jelley, was a member of Owairaka Athletic Club and applied the Lydiard
principles famously.
Walker broke the world mile record with 3:49.4 in 1975 after a period of training
over the Waiatarua circuit with Kevin Ryan, the top New Zealand marathoner of the
time. Eight years later, in 1983, he trained on the same circuit with marathoner
Chris Pilone, and subsequently he ran his PB over the mile, 3:49.08, still the
New Zealand record.