When measuring exercise intensity many triathletes use the old school method of listening to their body such as how hard they’re breathing, how their muscles feel, sweat rate, how tight their chest feels or how hard their heart is pounding out of their chest. It has worked well for many triathletes in the past however with the latest heart rate technology you can get more accurate data on how hard your cardiovascular system is working and use this data to dial in your training zones more accurately.


Sadly most people use their heart rate monitors to see how high their heart rate gets to in training or to measure their resting heart rate in the morning. The benefits of using heart rate training is not fully understood therefore the purpose of this blog post is to explain many of the benefits and how the data can be applied to help you dial in your training zones to improve performance. The how and when to use heart rate data in training is important as it is only effective when used correctly.


When determining your heart rate zones they have to be specific to the sport or discipline so for example a triathlete is going to have separate heart rate zones for each of the three disciplines of swimming, cycling an running. Your heart rate will be specific to that particular activity or discipline. One triathlete may exhibit a higher max heart rate on the run compared to the bike or swim portion of the race compared to another triathlete who may be the opposite.


To learn your maximum heart rate for a particular sport you can wear a heart rate monitor yourself and push yourself as close to your max exercise intensity for between four and ten minutes to see how high it reaches however this is not recommended while unsupervised or if you don’t know your heart condition. It would be safer get it measured more accurately by an exercise physiologist in a lab setting during a VO2 max test for example.


Alternatively if this all sounds too exhausting you can estimate it using many different formulas such as the traditional method of heart rate max using your age subtracted by 220 to give you your max heart rate in beats per minute however this method has no solid scientific basis. The Karvonen method or heart rate reserve (HRR) formula which is Target Heart Rate Intensity Zone = ((max HR − resting HR) × %Intensity) + resting HR. Women should use the following formula as a study found that the traditional method of calculating max heart rate was overestimating peak heart rates for women and came up with a more accurate formula for women as follows; 206 minus 88 percent of their age: For a 50-year-old, 206 – (50 x 0.88) = 162 bpm.


Another popular method is the Maffetone method as follows.

  1. Subtract your age from 180
  2. Modify this number by selecting among the following categories the one that best matches your fitness and health profile
  3. If you have or are recovering from a major illness (heart disease, any operation or hospital stay, etc), or are on any regular medication, subtract and additional 10.
  4. If you are injured or have regressed in training or competition, get more than two colds or bouts of flu per year, have allergies or asthma, or if you have been inconsistent or are just getting back into training, subtract an additional 5.
  5. If you have been training consistently (at least 4 times weekly) for up to two years without any of the problems just mentioned, keep the number (180-age) the same.
  6. If you have been training for more than two years without any of the problems listed above, and have made progress in competition without injury, add 5.


I have suggested the Maffetone method to some of my clients and the feedback I get is that they have a hard time running that slow to keep their heart rate down low enough in the lower heart rate zones. They are used to pushing themselves closer to their max heart rate on a regular basis and unfamiliar with slowing it down to stay within a certain zone and build their aerobic base. However I believe that going slower on certain days to allow your body to recover will allow you to go extra hard on important days that matter. I believe that sometimes you have to slow it down to enable your body to adapt and get faster over time. If you are constantly pushing your body to it’s limit every workout then you are going to burnout pretty quick and lose any gains you have made in training.


Many of my clients are concerned about their heart rate being too high or too low and it can be a cause of stress for some people. It shouldn’t be as your heart rate will fluctuate throughout the day. Heart rate is typically lowest in the morning upon waking and will increase or decrease depending on how active you are during the day and is a reflection on your body’s need for oxygen.


As your fitness improves your heart rate at any exercise intensity should fall. This is an easy way to gauge improvements in fitness over time by comparing your heart rate data at the same running speed, cycling wattage or swimming speed. Physiological training adaptations such as increases in cardiac output and stroke volume should result in a decrease in heart rate and it should also return to resting levels quicker as you recover. If you notice that your heart rate is higher than usual at the same exercise intensity then you should probably listen to your body and rest as this could be a sign of overtraining.


By using a heart rate monitor during training you will be in a better position to know how your body responds to training and what heart rate you can sustain at different exercise intensities. As well as learning how quickly your heart rate returns to normal resting levels after training therefore you will know if you are exhibiting signs of overtraining and be able to adjust your training load and rest to compensate.


When designing a training program for my clients once I have established their max heart rate typically after a VO2 max test I can then prescribe their training zones based on percentages of their max heart rate. I use five different training zones which target different energy systems and have different physiological adaptations or outcomes. See figure 1 below for more details about each zone.



Heart rate

Heart rate training zones




Zone 1: After an intense training session or race I recommend doing a recovery run the day after to help speed up recovery and remove waste products and soreness in the muscles. To improve lactate threshold you should spend 1-2 training sessions per week in one of the lactate tolerance zones. To improve your aerobic endurance you should spend 1-2 times per week performing longer slower sessions in the aerobic capacity zones. To improve your anaerobic capacity you should include plenty of sprint/interval training 1-2 times per week.


Zone 2: Easy running should be done to establish base mileage and improve economy. Sessions should be for longer than 30 minutes at a heart rate or speed under 2mmol/L blood lactate. This should be done on a rest day or after a big race to speed up recovery.


Zone 3: Steady running should be between 30 and 90 minutes at a pace to maintain lactate levels between 2 and 4 mmol/L.  This should be done 2-3 times per week.


Zone 4: Threshold running is closely related to exercise tolerance and race intensity. This intensity is used for long distance training and is the speed or heart rate required to produce blood lactate levels at or just slightly above 4mmol/L. By training at or slightly above this intensity improves performance over 5k and longer distance events. This type of training can be continuous or as interval sessions of 20 to 50 minutes in duration.  I recommend exercising at this intensity 1-2 times per week.


Zone 5: High-intensity interval training is for short burst sprints under 60 seconds in duration. This intensity should be above 4 mmol/L lactate concentration. The interval duration, speed, and rest interval can be manipulated depending on the outcome of the session. This should be max intensity so a heart rate as close to your max heart rate and a speed as fast as possible. For example using a work rest ratio of 1:3 you can sprint for 10 seconds then give yourself 30 seconds recovery and repeat up to 10 times. Once this becomes easier you can reduce the rest or increase the work from 10 seconds to 30, 45 or 60 seconds until you can manage a 1:1 work rest ratio of 60 seconds sprint and 60 seconds rest. This should be done no more than twice a week due to the high intensity and with an easy day or rest day in between to help the body adapt and recover.



Heart rate variability (HRV) is a measure of your autonomic nervous system and is considered one of the best objective metrics for physical fitness and determining your body’s ability to perform. HRV is the tiny beat to beat differences in the exact timing of multiple heart beats over time. So if your heart rate is 60 beats per minute it is not actually beating once every second.


For example, the gap between heart beats might vary significantly and could range from 0.8 to 1.2 seconds in a person with a heart rate of 60 beats per minute. It is found that the greater the heart rate variability, the healthier the heart and the more balanced your nervous system. It means that your body is adapting well to the environment and performing at it’s best. Heart rate variability is reduced when the sympathetic nervous system is more active and is increased when parasympathetic activity is increased.


HRV stops during exercise at intensities above 50% VO2 max, when sympathetic activity is increased. Changes in HRV measured at night might provide an accurate method to optimize training and prevent overtraining Pichot et al (2000). HRV is highly individualized and fluctuates greatly throughout the day and from one person to another. Young people tend to have a higher HRV than older people, males often have a slightly higher HRV than females and elite athletes tend to have a greater HRV than most especially endurance athletes such as triathletes.


HRV is affected by many factors including level of training and the frequency and intensity of your workouts, lifestyle factors such as what you eat and how much sleep you’re getting and then there are the biological factors out with our control such as age, gender and genetics as some people are just born with a higher HRV than others.


For those looking to improve their HRV there are a few methods you can do such as training smarter not harder so you are giving your body sufficient rest to recover. Drink more water. Hydration is key as the better hydrated you are the easier it is for your blood to circulate and deliver oxygen and nutrients to your body. Avoid alcohol as one night of heavy drinking can negatively affect your HRV for up to 5 days. Healthy diet and timing of eating is important as poor nutrition and eating late at night can also have a negative effect on HRV. The quality and consistency of your sleep is very important so going to bed and waking up at the same times each day makes a difference.


I recommend changing the frequency, intensity and duration of your workouts each week based on your HRV rather than follow a pre-determined training program to ensure you give your body enough time to recover. When your HRV is high your body is better able to take on a greater workout and when it is low it is a sign to taper off.


If you want to find out your maximum heart rate while running or cycling I can help. I perform VO2 max and lactate testing while monitoring heart rate, speed, calories burned, power, gross cycling efficiency, RPE and much more. Message me for more details. Let me know if you have any questions about this topic in the comments below. Thanks.





Maffetone, Allen. The big book of endurance training and racing (2010)

Noakes. Lore of running. Fourth edition. (2001)

Pichot et al. Relation between heart rate variability and training load in middle-distance runners. (2000)

Train with Heart Rate, Watch Performances Soar and Fat Melt Away!!!