After my last post I received a couple of questions from athletes asking if they should avoid training in zone 3 using my heart rate zone system. It’s a good question and one that comes up quite frequently, it seems. Here’s what I think.
There is nothing inherently wrong about training in zone 3 so long as it is beneficial for your race goals. If you are racing in events that are longer than about 2 or 3 hours and shorter than about 6 or 7 hours you will spend a lot of time in zone 3. For example, an experienced marathon runner will be in zone 3 and even zone 4 for much of the race.
Of course, as with anything in sport there are exceptions. Novices will find it incredibly difficult to maintain zone 3 for long periods of time. They will often fade and fail to finish events of such durations if they attempt to hold zone 3. On the other hand, pro triathletes in an Ironman-distance race are in zone 3 for much of their 8 to 9 hours. Road cyclists will typically see a lot of anaerobic time (zone 5) in events that are 2 to 7 hours long. These anaerobic endurance and anaerobic capacity efforts will determine the selections for lead groups. But when in the pack they will typically be riding zone 3. So zone 3 training can be quite effective if you race at such distances.
So why all of the concern about zone 3? Well, if you don’t race in events of these durations then zone 3 can possibly waste a lot of time. Zone 3 is what may be called “happy hard.” It’s challenging enough that you feel as if you are accomplishing something (after all, it’s kind of hard) and you can do it for a fairly long time. That makes you happy. But again, if not racing at this intensity then your workout may not have accomplished much in the way of race-specific fitness. That would certainly be the case if your event is zone-4 or -5 dominant, such as a sprint- or fast Olympic-distance triathlon, or a criterium race. In this case you would not have advanced your fitness (if in the Build period), yet there would still be a need to recover from such a zone-3 session. So you may wind up losing valuable training in the near future.
That said, I have athletes do a considerable amount of zone 3 training in Base 2. It’s great for building muscular endurance early in the season. But as we progress into Base 3 and the Build period the training intensity becomes more like the race – whatever that may be for the athlete in question.
It’s not just zone 3 which may waste your time by demanding recovery with little to show for it. Extensive Build period training in any zone which will not be used in the race can waste your training time by creating a need for extended post-workout recovery. For example, I sometimes run into triathletes training for an Ironman who do lots of zone 5 training. I would argue that with very few exceptions this is pretty much a waste of time.
So don’t rule out zone 3 as being wasteful. It may not be. The bottom line is, as I’ve said here before, your training (which is mostly intensity-oriented for the advanced athlete) should become increasingly like the race as you move closer to the event on the calendar.