Using four intensity levels I have the following:
VO2 V: 170-188bpm
Threshold T: 160-169bpm
Endurance E: 141-159bpm
Base B: <= 140bpm
HR maximum is 188bpm.
Resting HR is approximately 40bpm, but I never worry about measuring it any more.
The key difference is how I define the Threshold zone. It used be 153-169bpm, but with my training progression and values from races, it is clear my threshold is well above 153 (which was taken from the Maffetone formula). Key reasoning for the upgrade is I was able to sustain a pace, that was a little below the point of lactate accumulation for about 30km (roughly 2 hours) during the marathon, which had me at heart rates around 160bpm. This supports the fact my point of lactate accumulation is above this level. At or above 169bpm is 10km race pace territory, where there is a very obvious increase in pain and burning in the working muscles. This is obviously when the point of rapid lactate accumulation begins. Therefore, the threshold zone would be between these values.
The second main difference is the increase and narrowing of my endurance zone. This is where the majority of my training will be spent in the hope of enhancing my aerobic conditioning. My biggest training gains were made during the four week period that I worked at this level. Maintaining a steady-state, slightly below the anaerobic/lactate/ventilatory threshold for extended periods provides a big stimulus. Apart from all the cardiovascular, pulmonary and metabolic adaptations, it allows for practice of running at faster paces. The approach of a moderate training load, repeated in an almost relentless style, (ie. no big contrast, or polarised training) has served me well previously. I first describe this I adjusted training to prevent from reaching an early peak: Until You Fell Better. It also puts the aerobic conditioning or endurance work around the level associated with the marathon aspects of Lydiard's training guidelines.
Of course there will be a reasonable amount of running at Base level, but most of this will be incorporated in to warm ups and cool downs. Which really is just supporting the main workload of each run. What needs to be remembered is the training is really aiming to hold a reasonable volume of training at Endurance level, day after day, with a little bit of varied paced-faster running added on top. Plus, the long run should be at around 2 hours, at Endurance. With this training style (as with most training), consistency will be important.