Life, Running, & Medicine.
Notes on life as I see it.

Saturday, April 19, 2008

Lactate Threshold & Maximum Sustained Heart Rate

Multi-step process for estimating Anaerobic Threshold using Maximal Sustained Heart Rate:
This is fundamentally different from the other two methods I posted previously in that you are estimating a heart rate that corresponds to your anaerobic threshold, NOT a specific pace.  Using this method your pace will vary a bit, but the idea is to run at a specific heart rate regardless of pace.  This is probably more accurate.
This technique is quite laborious and requires repeated 45 minute runs on a treadmill.  The premise is that your LT correlates very well to the maximal heart rate sustainable (HRms) for a thirty minute period.  It is described in Vobejda C et al. Estimating MLSS From Heart Rate … Int J Sports Med 2006; 27: 368–372.
STEP 1: Initially you should set your target HR at 165 or 175.
  1. First you need a heart rate monitor that measures and outputs in real time.
  2. Get on a treadmill, adjust grade to 1%.  Slowly increase pace over 15 minutes until you hit your target HR.
  3. Run for 30 more minutes at this target HR.  Continuously adjust the pace up or down to keep your target HR.
  4. If you must stop early, then stop early ("exhaustion")
STEP 2:  Next we start repeating the test, with a 1-2 day break in between, adjusting target HR.
  • Increase your target HR by 10 beats and redo the test above.
  • When you reach an unsustainable target HR (exhaustion), redo the test above but decrease your target by 5 beats.
  • The goal is to zero-in on the max HR you can sustain for 30 minutes (HRms) regardless of pace.
Note that this estimates your LT as a heart rate, not a running pace.  So to train using this method you need to constantly adjust your pace in order to maintain your personal HRms.  As you continue to train at your HRms won't change much but your pace at the HRms will improve.
An example:
Martha runs on a treadmill, starting slow and building up speed over 15 minutes until her heart rate is 165 (for her an 8 min/mile pace).  Over the next 30 minutes she is able to keep her heart rate 165 by slowly decreasing her pace to 9 min/mile.  The next day she gets on the treadmill and slowly increases pace until her heart rate is 175 (a 7:45 pace), and is able to maintain HR 175 for 30 minutes by decreasing her pace somewhat as she runs.  On day 3 Martha runs again and reaches HR 185 (a 7:00 pace).  She struggles to keep from exhausting.  Finally despite reducing the pace she is too fatigued to keep up a pace high enough to give her HR 185 and she quits early.  On day 4 Martha redoes to the test, slowly increasing pace to get her HR to 180 (7:30 pace).  She is able to run for 30 minutes at a HR 180, even though reducing her pace to 8:30.  So Martha's HRms is between 180 and 185.
Martha can then tailor her runs in the in the future to keep a 180-185 heart rate (by wearing a HR monitor and adjusting pace).  This will build her endurance the fastest.  If Martha is in "pretty good shape" to begin with her HRms probably won't change, but her distance running pace should improve.  I suspect that if Martha was "a little fluffy" still her HRms would creep up after further training.
Let me know if anyone has tried this method.

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