For me at this time of the year I use the Grind as my tempo training run. It is a great way to keep the HR close to threshold for 30-40 minutes with no real impact on the legs unlike a hard tempo run on the pavement. It also builds the strength that is necessary to run well in the longer trail races that I am currently preparing for. Here is my HR profiles from my last two sessions. My HR is high but in a race up the Grind my HR average is 5-10 beats higher 190+/Ave HR over the course. Note how the HR Ave dropped one week after my first session even though my time was the same, I find this happens quite rapidly once I start doing these sessions.
Grouse Grind, Aug 21, 2007.
Ave HR: 185
Max HR: 190
Min HR: 154
Time in Zone 5: 00:34:35
Grouse Grind, Aug 28, 2007.
Ave HR: 179
Max HR: 186
Min HR: 151
Time in Zone 5: 00:15:38
