Too Anaerobic

Did some research and realized that in order to go longer, I need to keep my heart rate a lot lower, which unfortunately means going slower. My max heart rate is about 185, so an average of 166 (what I did on my run today) is about 89% of max. For the first several miles, I was between 150 and 155, so that means that my heart rate rose considerably in the later part of the run.

Here's what I found on the web in a early 2007 edition of Performance Pro:

The anaerobic zone – 80% to 90%

Training in this zone will develop your lactic acid system. In this zone your individual anaerobic threshold is found, which is sometimes referred to as the point of deflection (POD). During these heart rates, the amount of fat being utilised as the main source of energy is greatly reduced and glycogen stored in the muscle is predominantly used. One of the by-products of burning this glycogen is a runner’s worst enemy – lactic acid. There comes a point where the body can no longer remove the lactic acid from the working muscles quick enough. This happens at an individual heart rate for everyone, and is accompanied by a rapid rise in heart rate and a slowing of running
pace. This is your anaerobic threshold or POD. Through the correct training, it is possible to delay the POD by being able to increase your ability to deal with the lactic acid for a longer period of time, or by pushing the POD higher.

Next week I'm going to try going out at an 8:55 min / mile pace and see how my heart rate responds.