Heart Rate Training (Lactate Threshold Based): * Introduction to Heart Rate Training * Training Intensity and Interval Description Heart Rate Reserve Zones: * Heart Rate Zones Calculator #1 * Heart Rate Zones Calculator #2 Max Heart Rate Calculation: * Predicted Maximum Heart Rate Calculator Miscellaneous: * Measuring Training Stress

http://www.thefinalsprint.com/2007/01/heart-rate-training/ Excerpt... Here’s a simple heart rate training program to increase lactate threshold: * Assuming your heart rate at lactate threshold is 170bpm * Start by completing two 6-10 minute runs approximately 5% below the lactate threshold heart rate. In this case it would be 162bpm. * Rest for 2-3 minutes between runs and complete this twice a week. * Gradually build up the length of each run or the number of repetitions (up to 6). Also increase your target heart rate up to your threshold (170bpm). * The target eventually is to reach a sustained 20minute run at or just above your threshold heart rate. * Complete a thorough cool down at the end of each session. Also re-test your lactate threshold every 6-8 weeks.

I've seen 80-88% of HRR quoted, as well as 85% of MHR. If you want a better idea consider running the 30 minute time trial: "Make sure to warm up well for 10 to 15 minutes before starting out. The field test is going to be an individual time trial of 30 minutes. The effort should be very hard, but not so hard that you slow down at the end, think race effort of about 10k running or 30k bike time trial effort. Start the time trial and make sure to press the start button on the heart rate monitor. After the first 10 minutes press the lap button and press the lap button again at 30 minutes. Cool down 5 to 10 minutes easy. The average heart rate over the last 20 minutes is your lactate threshold estimate." - from http://www.endurancefactor.com/Articles/article-heartintro.htm