Lydiard and the Quarter Mile
It turns out that the great coach Clyde Hart (maker of Olympic gold medalists Michael Johnson, Jeremy Wariner and Darold Williamson) found that "the key to running fast 400s is to slow down." Hart's method of training quarter-milers came about when trying to get an injury-prone Michael Johnson through a full season of racing. Hart's system is Lydiard-like in that it begins with a large volume of easier running (to build strength and aerobic capacity — Hart believes the 400 is 40% aerobic), then gradually progresses to a smaller volume of faster running. In the autumn his athletes start with 20 x 200m "at a very slow pace, about 40 seconds each, on the grass." Now 40 seconds for 200 metres is incredibly slow for an athlete with a PB of 20 seconds or less. These are done with a short recovery. As training progresses "pace quickens and the repetitions shrink, but never to the point of full-speed sprints." Eventually his athletes might be running 6 x 200m in 26 seconds with a 90 second recovery. Training 'slowly' didn't produce plodding runners with fast-twitch depleted muscles. It produced athletes with the aerobic capacity to withstand a full racing season and the multiple rounds of championship competition.
Janene has blogged about the 80:20 rule of training for distance runners (which states that 80% of running should be below lactate threshold and 20% above). This ratio is more likely to be 85:15 or 90:10 for elite distance runners. What's confusing for recreational runners is that the perfect ratio varies according to the weekly volume run, age, and individual response. If running volume and frequency is low (for example, 3 days per week for a total of 40 kilometres), then the best ratio of 'easy' to 'fast' running might be 30:70 or 50:50. As volume is increased, the ratio must change. For example, it would be physically impossible to run 160 kilometres per week with 70% of that running being above lactate threshold. One pay-off with higher volume training is that the volume of 'above lactate threshold' running can be higher.