Intensity Factor

Having chosen to train using the Heart Rate Zone method (more specifically found in Joe Friel's "Total Heart Rate Training") I've been learning and focusing on a few things. 

What are my `heart rate zones?'  Friel and others propose a few methods that generally home in on the upper limit beats per minute figure.  That would establish the anchor of Heart Rate Zone # 5.  For example, let's say that my highest bpm figure is 170.  In Friel's book he offers a chart that arrays HRZs from #1 to #5c.  Here they are:

  93-130 HRZ #1 (Active Recovery)
130-143 HRZ #2 (Aerobic Threshold)
144-148 HRZ #3 (Tempo)
149-159 HRZ #4 (Sub-Lactate Threshold)
160-163 HRZ #5A (Lactate Threshold)
164-169 HRZ #5B (Aerobic Capacity)
170 HRZ #5C (Anaerobic Capacity)

Well enough.

I then applied these HRZs to 5 training / racing events over the past 4 months.  How much time did I spend in each HRZ for each event?

To come up with an event `Intensity Factor' I developed this equation:

A = Total minutes of event
B = (Total minutes in HRZ #1) x 1
C = (Total minutes in HRZ #2) x 2
D = (Total minutes in HRZ #3) x 3
E = (Total minutes in HRZ #4) x 4
F = (Total minutes in HRZ #5) x 5

(B+C+D+E+F) / A = Intensity Factor

Example # One: A race I completed on September 16:

• 52.1 miles
• 4,670 feet of climbing
• 2:48:00 (168) total minutes of event (A)
•    111 minutes ascending;
•      57 minutes descending;
• B = 12
• C = 92
• D = 24
• E = 25
• F = 0
• (15 minutes below 93 bpm)

The Intensity Factor is 2.2.  That is, this would be a race where a good deal of the time was spent at the Aerobic Threshold (HRZ # 2) Zone.

Example # Two:  At another event I came up with an Intensity Factor of 1.0.  I completed 244 miles in 15:09:00 (909 minutes).  Total climbing was 2,400 feet (a very flat course).  I spent all but 46 minutes (HRZ # 2) in HRZ # 1.  This event was completed within a completely Aerobic pace. 

Example # Three:  Yesterday I completed a training event of 81.4 miles in 7 hours (420 minutes) flat.  Ascending and descending feet were 8,440.  Ascending time was twice that of descending time.  I spent the entire event in HRZ #1 (93 - 130 bpm).  The Intensity Factor for this event was also 1.0.

Summarizing:

• The first example (52.1 miles) was a relatively short race.
• The second example involved 3 times the miles covered than the third example (81.4 miles v. 244 miles) but virtually no climbing at all.
• The third example (81.4 miles with 8,440 feet of climbing and descending) demonstrates the necessity of `pacing' rather than `racing.'

What sense does this make?

1. At relatively short events (especially where there is a great deal of descending where the heart rate drops to as low as 64 bpm) I can deliberately enter the anaerobic threshold and increase the bpm's for a short period of time, not concerned with lactate buildup and other changes in blood chemistry. 
2. At events of significant distance and climbing it is critical to remain comfortably in the aerobic zones. 
3. Importantly, at events of great length and time duration (ultra / endurance events) time off the bike reduces the number of miles covered. 
4. The key variables to a winning performance, then, during ultraracing are:

• not exceeding the upper limit of HRZ #1;
• remaining on the bike with forward movement for as long as possible;
• hydration;
• nutrition;
• sleep management. 

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These results may seem obvious and common knowledge to us.  In fact, there is nothing in the data that surprised me (except for the effect that climbing feet has on miles covered - literally a reduction in miles covered by a third).  But, it is confirming (for me) to have the tangible evidence, personal experience and data to support the `common knowledge.'