Heart Rate Training Zones

A target zone is a heart rate, expressed as a percentage of your maximum heart rate, that you can use a guide to maintain a specified intensity level during exercise training. There are different target zones for different types of levels of exercise you chose to undertake.

Activity in this zone is low intensity. It is where you perform light exercise such as gentle walking, stretching and light yoga. Whilst you don't gain significant cardiovascular improvements by training in this zone, this level of intensity can be very restorative for athletes, especially after hard training sessions, or racing so should be included as part of your training program.

Activity in this zone means you are working at the minimum intensity required to create an aerobic training adaption. This is the general fitness zone, which is the lowest end of the aerobic zone where it is possible to develop basic aerobic capacity provided you exercise for at least 30 minutes. In this zone, the body utilises more fat than carbohydrate as an energy source, so is a very efficient endurance pace that is ideal for long slow distances. You will still be able to speak in sentences at this intensity level so you should feel as if you could go all day.

Activity in this zone for long periods is ideal for developing your cardiovascular endurance. This is the ideal endurance training zone because it is the upper end of the aerobic zone where you can extend your aerobic capacity by training your body to adapt to using fat as a fuel source to conserve carbohydrate (glycogen). Typically, the best fitness benefits come from training in this zone for 20 - 60 minutes. You will be breathing very hard and not able to talk fluently but still able to speak in short phrases. When training adaptions have occurred you'll find yourself able to run some of your long runs, rides or swims at up to 75% HRmax.

Activity in this zone is purely anaerobic, hardcore effort and can only be sustained for a short duration of perhaps 10-20 minutes. This exertion level takes you to the limit where your body begins to produce lactic acid. At this point, you've reached your lactate threshold, and your body switches to anerobic metabolism where fat is no longer used as the main energy source so the body switches to use stored glycogen instead.

However the effectiveness of anaerobic activity can be improved through training. In other words, it is possible to improve your intense endurance so that the onset of lactate theshold is delayed, which enables you to work longer at higher speed.

This is a very important zone for competitive athletes to use in their training regularly, as it allows your body to adapt to excess lactic acid in the bloodstream, enabling you to build speed, power, and strength. You will know when you've hit this zone because you will be unable to speak, except a single gasped word at a time. Sprint distance triathletes will race in this zone, and learn to keep time above lactate threshold for important tactical surges only. The ideal race pace lies just below the lactate threshold, where the body will utilise a mix of the aerobic and anerobic energy systems to maximise intense endurance.

Training in this zone will only be possible for short periods because at these heart rate levels you've reached your VO2 Max. Using Zone 5 in training will develop your fast twitch muscles, which helps to improve your body's capacity for speed. This zone is reserved for interval training and sprint finish line efforts as most people can only sustain these heart rate levels for a few minutes at a time.

See Training Intensity article for more information about high intensity interval training.

The zones above obviously need to correspond with meaningful bpm rates to enable you to know when you've reached a given zone. If you're not using a heart rate monitor computer to do this for you, you'll need to look up a reference sheet probably from the internet or in a book. What you'll find however is that the bpm values quoted for each zone are based on the "average" value for resting heart rate and an age-based value for determining the maximum heart rate. Whilst the average person might have a resting heart rate of 60-70bpm, the average "athlete" will more likely have a resting heart rate of 40-55 bpm. Also, age-based calculations of determining max heart rate are only accurate for about 80% of athletes, with some people showing a variance of up to 20 bpm + or - from the average values.

Because athletes have lower resting heart rates, the maximum heart rates and target heart rates for athletes obviously vary from those of sedentary or less fit individuals.

What this means for athletes, is that when using target heart zones you must ensure you ignore the given the bpm rates, and re-calculate the bpm ranges for each zone based on your own personal heart rates for RHR, and HRMax. If you use a computerised HRM you will also need to adjust the values in the settings. We've given the formula for calculating your bpm for any given zone value at the end of this article.

Finding your true HRmax

To determine your maximum heart rate (HRmax) you really should do a stress test under medical controlled conditions. Most times, you won't have hit your maximum heart rate in your workouts, so look through your activity logs and see what your max has been and then expect it to lie a few bpm above or below that. Once you know your maximum heart rate, you can re-calculate the zone values (using the formula at the end of this article) for each of the training zones above.

Subtract your Resting Heart Rate (RHR) from your Maximum Heart Rate (HRmax) to find your working heart rate (WHR)

Calculate the required Zone% of the WHR to arrive at "Z"
Add "Z" and your RHR together to find your target heart rate

Example:
If you know your MHR is 180 and your RHR is 60, you can find out the heart rate (bpm) at which you should be targetting to exercise at 70% HRmax (ie. zone 3)

By using the formula MHR - RHR = 180 - 60 = 120 (this is your WHR)
70% of 120 = 84 (this is Z)
84 + RHR = 84 + 60 = 144 bpm (this is your target heart rate for 70%HRmax)

Now, using the 5 zones above, you should go ahead and work out what bpm rates this would equate to for yourself and print this off and keep it handy.

Training with HRMs in Zones

Be sure to go into your profile settings and modify the values for resting heart rate and max heart rate as this will affect the calculations used by the computer to determine your activity zone.You can set alerts on most HRMs to guide you when you are exceeding or falling below a nominated zone or heart rate too.

Factoring in Fitness Changes

To maintain accuracy it is best to retest your RHR every month. As your aerobic fitness changes, so too should your maximum heart rate change. Studies have shown that HRmax declines as V02max increases, so as your heart becomes more efficient you should expect a lower HRmax than you were recording earlier in the season, with a range of 3-7% being quoted as the typical shift caused from successful training adaptations. These shifts will make a difference to the formula for determining which zone you are actually working in, so always try to keep your profile details accurate if relying on computer HRM and using heart rate training zones to guide the intensity of your sessions.