Training Stress Indicators - Heart Rate

This past weekend was my first planned Back to Back session.  16.5 miles Saturday followed by 17.0 miles on Sunday.  I've gone into longer runs with more fear and concern than this weekend.  For me, a four or five hour training run generates some anxiety (unless I have the opportunity to do it in the mountains!).  Entering the weekend with 5 hours of running felt like the normal day-to-day grind.

I was aware this would put my body into a level of stress.  So leading into it, I started tracking my heart rate more closely, even incorporating a daily Orthostatic Heart Rate (OHR) test.  Using heart rate to gauge stress is a well understood science.

"Why would such heart-rate accelerations be a warning sign for overtraining?  Bear in mind that pulse rate is controlled by the nervous system, and the nervous system is one of the first three systems to show signs of overtraining. Thus, nervous system irregularities show up as changes in heart rate, which you can monitor quite easily, without the need for expensive endocrine or immune-system tests."  - Sports Performance Bullentin (http://www.pponline.co.uk/encyc/0410.htm#)

Previously I performed this test regularly when preparing for my first marathon in 2011.  I found this two minute test to more indicative of training stress than purely tracking deviations in my morning sample low heart rate.  As an example, a two beats per minute (bpm) variance increase in my low morning heart rate could mean absolutely nothing.  Alternatively, it could also be an indicator of training stress.  Effectively, the data sample is too small to make a determination.  It was one number.  The best test I found was the two minute long OHR. Deviation over a two minute period is a sign of stress (or rest, depending on which side of the trend line I am on).  I trend both 5 days and 3 weeks.  This allows me to see if I am currently under extreme training stress/load by measuring today's OHR against both the 5 day and 3 week.  Theory calls out the 15/20 second and 90 second interval as key markers.  For me, a deviation of +5 bpm above the norm represents significant stress from yesterday's workout (or the onset of an illness).  Negative deviation represents recovery/rest.

My sample period is still too short, as I started performing the test July 23rd.  With a large enough sample size, I can look beyond the acute stress of a single day (referenced above), and spot cumulative strain when comparing the 5 day to 3 week trend.  With this, I will be more cautious with my variance.  A +5 bpm increase from my 5 day average to 3 week is extremely high - something I don't believe I want to get to.  This represents an extended period of stress, which can result in injury or illness.   Currently my variance between the 5 day and 3 week is negative, which is a good sign that general training load isn't to the point where burnout (or serious illness, ie Mono) will happen.  This is a risk with multiple weeks of intensive load.

After this weekend, I was eager to see how my OHR stacked up on Monday morning.  Unfortunately, it was a bit late as I came down with something over night Sunday (feverish).  The OHR did show the spike, as I was considerably higher almost the entire 2 minute cycle.   I was well over the +5 bpm, with several intervals hitting +11 bpm above norm.  This called for a day off - not just from running, but included any core and flexibility activity.

Biomarkers as of Monday, July 29 2014

In hindsight, the illness wasn't entirely the result of the hard workouts.  We attended three birthday parties over the weekend.  My ability to follow a regimented nutritional recovery plan was off the table. All workouts weaken the immune system - so it is vital to get the nutrients in place quickly to return the body to homeostasis. My eating habits this weekend significantly hampered my ability to do so.  To compound the problem, I was stung by a yellow jacket Sunday evening.  Normally not a problem for me, as I have no allergies.  Now knowing my state at that point, I believe the body simply was overwhelmed with fatigue and a weak immune system, which made me vulnerable.  Tipping point...f'ing yellow jacket.

The fever broke mid/late afternoon Monday.  Despite the urge to do something, I understand the importance of rest to an athlete's development.  This was, after-all, supposed to be a recovery week.  So day off, and early to bed.  Tuesday morning OHR showed marked improvement, but still noted several sample points between 5 second 7 bmp above 5 day trend (OHR Deviation Analysis, 5 Day Deviation line), so today will be another rest day.  Generally I feel back to normal. As such, I will not give up on some flexibility and core work (Wharton's AIS and Planks today).  Let's see what tomorrow shows!