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Friday, September 23, 2011

Personalize Your Target Heart Rate Zones

I compared a few books that discussed heart rate training and was surprised to see the BIG differences between recommended target heart rate zones.  Apparently no one could agree upon a universal zone that would work for everyone, and there's a reason for this.  Individual variability.  While some people are elite athletes, some are elite couch potatoes- their cardiorespiratory systems are obviously the same and will definitely need personalized zones to work with.  What the books below lacked was a method of personalization.  Below are some rules that I created which helped me personalize my own target heart rate zones.
  • Rule 1:  There are three energy systems... so there really should only be a three zones.
    • There should be a zone for each metabolic system; the ATP-PC, lactic acid and aerobic system.  NASM followed this rule, but didn't give much room within the aerobic zone to allow for recovery.
  • Rule 2:  The ATP-PC and aerobic zones should be designed around lactic threshold.
    • You will never actually know the aerobic and power zones without knowing where lactic threshold occurs.  Lactic threshold can occur anywhere from 75 percent to 85 percent (1).  After finding the heart rate that represents lactic threshold, keep the LT zone within 5%.  
    • My LT Test: If your scared of needles like me, try the test I created to estimate lactic threshold.  Be sure you're cleared by a physician before performing this test- it will put a lot of stress on the cardiovascular system!  After a five minute warm up, ride as fast as possible for 12 minutes.  Why 12 minutes?  The test needs to be short enough in duration to prevent cardiac drift and local muscle fatigue from skewing the results.  Cadence should be high (90-100 rpm) to promote circulation and activity from the aerobic system.  At the end of every three minute segment, record heart rate.  The average heart rate from the last three measurements will give you a good estimate of lactic threshold.  Add 10% to create the upper limit of the LT zone.  End the test with a 5-10 minute progressive cool down.
  • Rule 3:  Don't give more than 100 percent.
    • This might be the one condition where giving less than 100% will give more in return.  As mentioned by ACSM, intensities above 100% HRmax produces smaller improvements in VO2 than intensities that are within 90-100% HRmax (4).  I think it's also important to note that intensities that are above 100% will also increase the risk of overtraining.
  • Rule 4:  Recovery should feel like recovery.
    • Don't restrict your recovery zone to a minimum of 65% HRmax just because a book tells you to.  If 65% HRmax feels hard or doesn't allow you to complete your intervals efficiently, go lower.  The goal for intervals is to perform the work portions at a consistently high intensity.  The recovery should be easy enough that the next work portion can be perform just as high as the last work interval.
  • Rule 5:  If you're exercising just for the health benefits, don't worry about details.  
    • Stick to the simple ACSM heart rate zones.  Although there are six zones, their zones are clearly defined and would be more appropriate for people new to exercise- not athletes.  The conversions from HRmax to HRR/ VO2R to RPE is very convenient.


Below are the THR zone recommendations from different sources.


Long-Distance Cycling by Dr. Burke & Ed Pavelka.  I was very happy with this book when they mentioned that the border (LT) between zones two and three differs based on individual differences.  An untrained cyclist may hit lactic threshold at 75% and an elite cyclist might reach LT at 85%.  Dr. Burke and Mr. Pavelka gave excellent advice regarding individual differences with LT and I liked that they recommended zones specific to each metabolic system.
  • Zone 1: Recovery = <65% HRmax
  • Zone 2: Aerobic endurance = 65% - 84% HRmax 
  • Zone 3: Lactic threshold = 85% - 94% HRmax
  • Zone 4: Anaerobic = 95% - 100% HRmax
Mastering Cycling by John Howard.  Based on the way the zones were described, it seemed like the heart rate recommendations were based more on opinion than research findings.  I would have liked this section more if the book mentioned that individual differences can throw off all of the ranges and provided suggestions to modify each zone.

Although the heart rate recommendations were a little iffy, I liked that he provided FTP "functional threshold power" recommendations based on Dr. Andrew Coggan and Hunter Allens book called Training and Racing with a Power Meter.  If you're unfamiliar with FTP, it's the maximum amount of power that can be held for an hour.  Unlike lactic threshold and ventilatory threshold, functional threshold power is a measurement of a mechanical variable, not a physiological one.  The functional threshold is the point where heart rate increases and power decreases; in other words, the point where you are fatigued.  Anyway, here are the recommendations below.
  • Zone 1: Active Recovery = 50 - 60% HRmax, ~55% FTP
  • Zone 2: Endurance = 70% HRmax, 56-75% FTP
  • Zone 3: Tempo = 60 - 70% HRmax, 76-90% FTP
  • Zone 4: Sweet Spot = 75 - 80% HRmax, no FTP recommendations...
  • Zone 5: VO2 max = 80 - 85% HRmax, 106-120% FTP
  • Zone 6: Anaerobic Capacity = 85 - 95% HRmax, 121-150% FTP
  • Zone 7: Neuromuscular Power = >95% HRmax, >150% FTP
American College of Sports Medicine, 1998.  Based on 20-60 min for 3-5 days per week.  Interval training programs with intensities 90-100% of VO2max lead to the greatest amount of improvement in VO2max.  Exceeding 100% will produce smaller improvements than the 90 to 100 percent range.
  • Very light: <35% HRmax
    • <20% HRR/ VO2R (<10 RPE)
  • Light: 35-54% HRmax
    • 20-39% HRR/ VO2R (10-11 RPE)
  • Moderate: 55-69% HRmax
    • 40-59% HRR/ VO2R (12-13 RPE)
  • Hard: 70-89% HRmax
    • 60-84% HRR/ VO2R (14-16 RPE)
  • Very Hard: greater than or equal to 90% HRmax
    • Greater than or equal to 85% HRR/ VO2R (17-19 RPE)
  • Maximal: 100% HRmax
    • 100% HRR/ VO2R (20 RPE)
National Academy of Sports Medicine 2010. These ranges were determined through respiratory quotients (RQ).  Respiratory quotient is calculated by dividing the volume of CO2 produced by the volume of O2 consumed.  This is a good way to measure effort and the dominant energy system.
  • Zone 1: Recovery/ Low Intensity = 65-75% HRmax or RQ 0.80-0.90
  • Zone 2: Anaerobic Threshold (AT)/ Higher Intensity = 80-85% HRmax or RQ 0.90-1.0
  • Zone 3: Above AT / High Intensity = 86-90% HRmax or RQ > 1.0

Resources:
  1. Burke, Ed, and Ed. Pavelka.The complete book of long-distance cycling: build the strength, skills, and confidence to ride as far as you want. Emmaus, Pa.: Rodale ;, 2000. Print.
  2. Clark, Micheal, Scott Lucett, and Donald T. Kirkendall.NASM's essentials of sports performance training. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2010. Print.
  3. Howard, John. Mastering cycling. Champaign, IL: Human Kinetics, 2010. Print.
  4. Thompson, Walter R., Neil F. Gordon, and Linda S. Pescatello. ACSM's guidelines for exercise testing and prescription. 8th ed.