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Updated: Aug 1, 2022

As I wrote about in this post on exercise intensity, you want to know with a reasonable accuracy what intensity you're exercising at. Exercising at different intensities allows us to train intelligently to meet our goals, be it lose weight, go faster or go further.

The science bit

When we exercise we derive energy from three energy systems depending on the intensity we are working at. Exercising very gently and you’ll be deriving nearly all of your energy from the aerobic system - burning fat, and improving your overall aerobic fitness. Train flat out and nearly all of your energy is supplied from the breakdown of carbohydrate without oxygen, training your anaerobic threshold.

So, to hit our goals intelligently, rather than just working out with no real game plan, we need to build a program that works us at the right intensities (training zones), for the right duration, accurately.

Using your heart rate to target intensity

In the previous article I discussed the reasons why heart-rate monitoring is one of the most accurate ways to monitor intensity, and these days most smart watches have some form of heart rate tracker, with a sensor that detects your heart rate on your wrist. Whilst this is a good place to start, it should be noted that the readings from a wrist monitor can be effected while you are training as the watch can often move around and sweat can effect the accuracy. If you can, look to pair your watch with a heart rate belt for a more accurate reading.

Dont worry, you dont have to run bare chested like in this stock image!

Finding your Maximum Heart Rate (MHR)

To work out your training zones, you first need to know your MHR. There are many different formulas that you can use to calculate your maximum heart rate (MHR) and find your personal heart-rate training zones. The easiest, but least accurate way is by using an age-based equation – the most common is simply 220 (222 for females) minus your age – so a 40-year-old man would have a theoretical MHR of 180. The problem with this method is it it doesn't factor in your current levels of fitness, genetics, body size etc and therefore is not that accurate.

Standard disclaimer goes here: if you have a health condition where all-out exercise might be dangerous (or if you’re not sure), get a doctor’s OK before trying any of this.

A more accurate method is to strap on a heart rate monitor and go and perform one of the following:

  • Run as fast as you can stand for three minutes. Rest for three minutes, then repeat the hard run again, and note the highest heart rate reading from the second trial.

  • 5K run. If you run that distance with every ounce of effort you’ve got, your highest reading toward the end of the race should be your max.

You’ll get the most accurate (highest) results if you come to the workout fresh (so don’t plan the test for the day after a hard workout), and make sure to do a long warmup that, even if it starts out easy, gets you working at moderate intensity as a ramp-up to the test.

Now you have your MHR, you can apply the percentages to find out what your zones look like. Many sports watches and fitness apps will calculate your zones for you once you input your MHR, or for my clients I will work this out (there are also online calculators such as this one from MyProCoach)

Training Intensity Zones

Training at the appropriate intensity is a key element to improving your performance and staying injury free. Harder is not always better. It goes without saying, the duration of exercise needs to be considered; you can go a lot longer in zone 1 than you can in zone 5!

Zones 1 & 2

% of max HR Range : 50-60% / 60-70%

Example Duration : 20-80 mins Zones 1 & 2 are great for those beginning a fitness program to build an aerobic base; improving our ability to take in oxygen and efficiently transport it to working muscles.  Our muscles are developing a greater ability to utilize oxygen to make fuel to support the workout.  Our capillary beds are expanding, and our heart and lungs are getting stronger.

These zones are also great for active recovery; after a hard workout, a very easy workout in zone 1 / 2 can accelerate recovery more than complete rest. Easy aerobic training stimulates circulation which speeds up the healing of tissues that have been damaged by intense training.

Training at zone 2 intensity (60-70%) is great for improving aerobic endurance, overloading the slow-twitch muscle fibers.

We also burn fat efficiently in zones 1 & 2.  The more fit we become, the more effective we become in using fat as a fuel source.  It is in these zones that we burn the highest ratio of calories from fat (as opposed to carbohydrate or protein). 

Zone 3

% of max HR Range : 70-80%

Example Duration : 10-40 mins

In zone 3 we are improving our aerobic fitness. The effort in this zone can be comfortable, but should not be easy. Conversation is possible, however, not as easy as Zone 2. We start to expand aerobic capacity to a greater extent and elevate anaerobic threshold.  By elevating our anaerobic threshold, we are increasing our ability to work at higher intensities for longer periods without fatigue.

Zone 4

% of max HR Range : 80-90%

Example Duration : 2-10 mins

In zone 4 we are increasing our maximum performance capacity; there will be muscular fatigue and heavy breathing! While aerobic conditioning is important to paddling performance, situations arise in races where the energy cost far exceeds your aerobic capacity. These situations call for high levels of anaerobic energy production followed by a period of recovery. We are working our anaerobic systems in zones 4 & 5.

Zone 5

% of max HR Range : 90-100%

Example Duration : Less than 5 minutes

Increases maximum sprint speed, firing up those fast twitch muscles!

Don't worry if all this sounds confusing; with a tailored SUP Coach training program I will work with you to find your MHR, and I'll work out your training zones and present it in a clear and understandable training plan to hit your goals!

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