heart rate zones

More winter time experimentation.  Running and spinning this week with heart rate monitor attached to Garmin 305. Looking for confirmation of pace and fitness for an upcoming marathon.  Never done this before.

Estimated a maximum heart rate on the order of 200 based on 4 mile run and 5k PR's a while back.  Yes, it's higher than formulas would estimate.  Consulted medical advice.  Normal?  Said to be within normal variation range.  Higher end max heart rate.
Heart rate of around 182-185 in a 'go like hell' spin class exercise this week. Thanks D! Resting rate of around 49-50. Marathon pace heart rate around 155-160 for 13 miles with training partner today.  Plug -n- chug into Marathon Guide heart rate calc. Results follow.

Marathon pace puts me in the middle of Zone 3 Aerobic Zone 70-80% of max.  So what's that mean?

Some references from Marathon Guide and from Running Times. (Thanks for subscription B!)

Heart rate of 160 puts me at about 70-75% of max, in the middle of  burning more fat and less glycogen. Hopefully where I can run a decent race. Seems to confirm thinking about fitness.

We shall see come race day.

-Larry