One last thing to note, I am listening to "Finding Ultra", by Rich Roll. I highly recommend reading/listening to this book. I'm only on chapter 9, but he has a great story and some great information for the endurance athlete. During today's ride he covered the point where his coach advised him that you must keep your heart rate in Zone 2 in order to increase the capacity and volume of mitochondria in your cells. These guys are the engines that allow you to perform over long distances. Rich's coach started him off at extremely short runs compared to what he was used to and he struggled to keep his heart rate down because he had a hard time keeping himself slowed down. He would also work in speed workouts during his training weeks, but they were designed to keep him in Zone 5 and nearer to his max capacity. He avoided the "gray zone"; zones 3-4 as these are not as beneficial to performance gains. In the end, he realized great improvements in his aerobic capacity. I probably don't explain it well enough here, but believe me, it was compelling stuff. This is the first mention I have come across talking about Zone 2 training increasing endurance, but it made a ton of sense.
After hearing that portion of the book, and the fact that I was on a ride in which I was trying to work on endurance, I tried pulling back my effort and getting my heart rate down around 140 bpm. My usual on the bike is more in the 150-160 range. Afterward I calculated my zones here on http://www.digifit.com/, I wasn't really sure what they were, and came up with the following charts. (below) It should be noted that these are unique to me and they they are not 100% accurate for me. HR zones are unique to the individual and to get the most accurate idea of what yours are you would have to get your lactate threshold heart rate measured, as I understand it. Regardless, the calculator at digifit.com provided good ballpark numbers that I feel are probably about right for me. The first two are standard calculations using various methods. The third chart is specific to the bike, which is a little lower than normal. Looking at these, when I am working endurance I want to try to stay around 140 on the bike and 150 on the run. I was aware that triathletes kept track of what "Zone" they were training in, but this is the first time I heard an explanation as to why this is so important in endurance sports. Workouts need to have a purpose, to work speed or endurance, and you need to stay in the proper zone to work these effectively. I'm not sure what zone, you should race in, so I I found this article at Active.com that explains it pretty well for the short (sprint and Olympic) courses: http://www.active.com/a3_articles/e172d8a2-d160-4a38-8a9f-4156afd160f4/1?page=1
Rich states that most weekend warriors just plug along training in the gray zones and wonder why they are not making significant improvements. That would definitely have applied to me. I am going to take this knowledge forward and try applying it to my training. I'll try to focus on being in either Z2 or Z5 during training and work both speed and endurance.