Lydiard borrowed the term and pacing from Holmer, the famed Swedish coach of world record holders from the 1940s. The scale by Holmer went like this:
7/8th effort = 2.5% slower than all out for that distance
3/4th effort = 5.0% "
1/2 effort = 7.5% "
1/4th effort = 10.0% "
Lydiard had a friend (who he coached)who was a mathematics teacher in Auckland. That friend calcuated tables for him. Lydiard revised it twice, but the jist of it was retained from Holmer.
As soon as his first tables became available and his first book a little while thereafter, Lydiard somewhat regretted that he had it printed. Why? He wanted the tables to be guidelines, not absolutes. He knew that a runner doesn't feel the same every day and 3/4th effort, for example, might vary a little bit. Regardless, he used the tables as a guide when coaching his runners but always gave the runner flexibility to make the pace fit the "effort."
In the 1950s, Bill Bowerman got ahold of Holmers essays on training and gave it to Peter Mundle, a student-athlete. In the essays was the chart that was also reviewed by Lydiard. So, at the very same time that Lydiard was using Holmer's effort chart, Bowerman was finding it useful too. Thus,
Bowerman use time trials to set subsequent training based upon the effor table created by Holmer as early as 1956. A 1-mile time trial to set "Date-Pace" was done at 3/4th effort for the first 1100 yards and the last 330 yards was run at full speed. The overall effect was a relaxed but quick effort over 1 mile. The date-pace intervals were then set for the next 21 days based upon the result. So, for example, Bill Bailie, in January, may be able to run an all-out 1 mile race in 4:08, but in his time trial to determine date-pace, he used the 3/4th effort for the first 3 and 1/4th laps and then full speed for the last 3/4th of one lap. The total time might be 4:16. During the next 3 weeks most of the intervals (440s or 660s) would be run at 64 per 440 yards pace. The 220s might be run at goal 1-mile pace (about 29 seconds).
So, both Lydiard and Bowerman used the Holmer method of effort based training - framed by mathematics. It was alwasy the combination of the two that worked so well for both coaches. Tinman