Training zones

I need to rethink my approach on using my heart rate monitor. On last night's run, I was trying to stay at around 93-97% of my estimated HRmax for the whole run. This proved to be impossible. My target range was 164-171, but whenever I went above about 165 bpm, my breathing became laboured, and I felt as though I was nearing exhaustion and that I would need to stop running imminently. I then had to drop down below 160 bpm to recover.

So I have read up a bit more about heart rates and decided to try a new approach, based on Lactate Threshold. This is the intensity of exercise at which lactic acid starts to build up in the muscles, and can be estimated as the highest intensity that can be sustained without significant discomfort, according to this article. A method is suggested here for estimating your own lactate threshold, but based on my run from last night, I would say mine is around 165 bpm. Based on this assumption I can define a number of training zones:

Training Zones for Lactate Threshold = 165 bpm
		Range as % of LT		MinHR	MaxHR
Zone 1	Active Recovery		80%		132
Zone 2	Aerobic Threshold	81%	89%	134	147
Zone 3	Tempo	90%	95%	149	157
Zone 4	Sublactate Threshold	96%	99%	158	163
Zone 5a	Lactate Threshold	100%	101%	165	167
Zone 5b	Aerobic Capacity	102%	105%	168	173
Zone 5c	Anaerobic Capacity	106%		175

This seems to make sense - firstly my original estimate for HRmax (177) now looks to be around the limit of anaerobic capacity, which is what I would expect. Secondly, most of my run yesterday was in Zone 3 (Tempo), which seems reasonable as this should be slightly faster than a comfortable pace, or at the point where I am pushing myself slightly.

This gives me some new target zones. For the moment I will try to do all my runs at tempo (Zone 3). Once I move onto Phase 2/3 of my plan, where I am alternating between short and medium runs, I will do the medium runs in Zone 3, and push up to Zone 4 for the short ones.

Once I move onto Phase 4/5 of my plan (see earlier post), where I introduce long runs and build up the total mileage, I will modify my original plan to include runs at different levels of intensity:

Mon	Rest
Tue	Short Run	Zone 4
Wed	Medium Run	Zone 3
Thu	Short Run	Zone 4
Fri	Rest
Sat	Medium Run	Zone 3
Sun	Long Run	Zone 2

This plan means that the rest days come either after a long run or a fast one. I may also experiment with interval training on some runs, i.e. short bursts of Zone 5 running, alternating with periods of recovery at Zone 1. This technique is supposed to build strength.

At some point I will also try to come up with a more accurate figure for Lactate Threshold, and I will measure it regularly so as to update the training zones table, as LT is supposed to increase slightly as fitness increases.