How to Calculate Target Heart Rate Zones

Keep things simple with three zones.

• If you want a quick and convenient method, use the NASM three zone system.  Assign a zone for each metabolic system: the ATP-PC, lactic acid and aerobic system.

Determine the lactic threshold zone first, then aerobic and ATP-PC zones.

• Lactic threshold can occur anywhere from 75 percent to 85 percent of HRmax (1).  After finding the heart rate that represents lactic threshold, keep the LT zone within a 5% upper and lower limit.
• 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 any maximal-effort test.  After a five minute warm up, ride at a maximal, steady effort for 12 minutes.  Why 12 minutes?  The test needs to be short enough to prevent cardiac drift and local muscle fatigue.  Record heart rate at three minute intervals.  The average of the last three measurements will give you a good estimate of lactic threshold.  Add and subtract 5% to create the upper and lower limit of the LT zone.  End the test with a 5-10 minute progressive cool down.

Don't give more than 100 percent.

• The American College of Sports Medicine found that intensities above 100% HRmax produced smaller improvements in VO2max than intensities that are within 90-100% HRmax (4).  It's also important to consider that intensities above 100% HRmax will also increase the risk of overtraining.

Recovery should feel like recovery.

• Don't assign a minimum value to the recovery zone.  If 65% HRmax feels too hard, it's ok to go lower, especially if it limits your ability to complete all intervals, or adds fatigue.

If you're exercising just for the health benefits:

• The ACSM heart rate zones are more appropriate for people new to exercise- not athletes.  The conversions from HRmax to HRR/ VO2R to RPE are 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.