With the boom in use of wearable technology devices, it is nice to know what the raw data information is actually telling you, and how it can used to strategically improve your fitness levels. With the fitbits and Garmin devices, you get a clear indication of heart rate levels during exercise, but should you just be aiming to get your heart rate as high as possible during exercise? Does a higher heart rate mean you are fitter, working harder, or working more efficiently than someone with a lower heart rate – possibly not! To just exercise at a high heart rate over long periods of exercise isn’t really a useful (or necessarily safe) indicator!
How can you use fitness parameters to your benefit?
Firstly, let’s define the main terms:
Resting heart rate
Don’t just sit down for a minute during the day and think that you will get an accurate indication of your resting heart (RHR). RHR is best calculated first thing in the morning, lying in bed, and monitoring your heart rate levels for a few minutes: Take the lowest level you see indicated on your device, record it, and repeat the process over 5 – 7 days. Take an average of these figures and you’ll have a reasonably good indication of what your true RHR is. Just make sure you’re not measuring or recording on any morning you feel unwell, or particularly stressed.
It’s worth putting some effort into getting RHR calculation right, because many other fitness parameters are based around your RHR, so if you get this bit wrong, the other calculations will also be incorrect.
RHR is also a great way to know if you are getting fitter – with all else being equal, if your RHR has become lower after a sustained period of exercise, then there’s a fair chance that you are actually fitter and your heart more efficient.
Finally RHR is also great indicator of when you need a rest. Often it will be consistently a little elevated if you are getting sick or it can even sit consistently lower than normal if you are a bit over trained- both indicating that you need a rest
Maximum heart rate
The very generalised rule for calculating your MHR is to simply subtract your age from 220. Whilst this may give you a figure “in the ballpark”, for those that are looking to structure a program based around MHR, it’s not really accurate enough.
The only way to get a truly accurate MHR figure is with the experts with proper physiological testing. However if you were to do 4 or 5 intense training sessions, where you’re working close to maximum, see what your MHR readings are for these sessions and you’ll probably have a more accurate estimate than 220 minus age.
An often used test to get a good idea of your MHR is to run a flat out sprint for approx. 30 seconds. Maybe do 2 or 3 reps with a five minute rests in between. You should find your HR will get close to its maximum. However, before embarking on this level of exercise intensity, you should have a health check with your GP and be given the “all clear” to participate in the activity first .
Establishing your training zones
If you can get an accurate indication of your RHR and MHR, you are in a position to develop a program that will suit the desired outcome of your fitness activity. Using a percentage of your MHR as a guide, you can target different types of fitness. For example, here’s a common guide, based on the sally Edwards research at Heart Zones:
| ZONE | NAME | %MHR | PURPOSE |
| 1 | Active Recovery | 50 – 60% | Recovery following a hard session; often a better choice than complete rest. Maintain activity without producing fatigue. |
| 2 | Endurance | 60 – 70% | Long sessions, often in the hours for cyclists but of medium stress.; teaches your body to burn fat as a fuel source. A great way to work on base fitness levels. |
| 3 | Tempo | 70 – 80% | Helps you sustain a consistently high pace – sessions are hard but reasonably comfortable. Teaches the body to store more glycogen as it is glycogen rather than fat that is mostly utilised at this level. Zone 3 training is often incorporated into a Zone 2 training session. |
| 4 | Threshold | 80 – 90% | Works on anaerobic threshold; short intensive bursts of exercise that produce lactic acid. Helps train for short bursts of speed or power during events. |
| 5 | VO2 max | 90 – 100% | A very fatiguing level that works on your cardiac output – how quickly your heart can pump the optimal level of blood to the working muscles. Increases maximum power and speed. |
Using HR to design a training session
Low MHR Training: Going slower might make you faster
This is a very popular training regime now, based a lot on the work of David Maffetone. Believe it or not, staying in Zone 1 and Zone 2 HR levels can actually make the heart more efficient. As you gain fitness, your cardio-vascular system becomes more efficient at providing blood to the required areas, meaning you get the same amount of oxygen to the working muscles with less heart effort.
Another major reason for endurance athletes to train at low HR levels is to help teach their body to oxidise fat as a main energy source rather than use up all their carbohydrate stores. Athletes who can efficiently use fat stores as an energy source may have an advantage in endurance sports where carbohydrate stores can get depleted (more of that in our next article)
For example, if you are not particularly fit you may find you can run 5km in 25 minutes keeping your heart rate at about 120 beats per minute. By training at a low MHR level, your heart becomes more efficient and the chances are in a fitter state you can keep your heart rate at around 120 beats per minute over 5km…and you’ve finished in 23 minutes; or you’ve completed the same 25 minutes run but covered 5.5km! These sessions are harder than you think – one of our fit SSPC physio’s simply couldn’t cope with the constant stopping (when running) to get his heart rate down to these zones. The training is boring and sessions need to be long, but research shows it to be effective.
High MHR Training: Burning Fat
Gyms seem to be full of HIIT (high intensity interval training) classes these days, and the idea is short but intense exercise sessions which target fat burning. Not only do short high intensity workouts burn fat, but they also contribute to fitness levels.
During a FIIT type session, you are aiming at your MHR getting into Zone 5 levels during short bursts of activity. On a bike it may be as simple as 5 or 6 x 30 second sprints, with plenty of rest in-between (4-5 minutes usually recommended).
Catalyst ran a great TV documentary in September 2015 titled “Fit in 6 minutes a week” based on this exercise format. The Catalyst subject completed 4 x 30 second sprints on a bike, with 4.5 minutes rest in between each sprint, for 20 minutes in total duration, 3 times a week (this where these headlines can be misleading –it’s actually 60 minutes of exercise a week, incorporating 6 minutes of intensity in this Catalyst example). At the end of 4 months, a 10% increase in VO2max (a measure of an athlete’s ability to perform sustained exercise) was demonstrated.
When it comes to fat burning, the literature seems to indicate that moving fast is your best friend. However don’t forget that if fat burning is a major goal, you need to turn some attention to your nutrition as well!
You also have to keep in mind that faster/ maximum intensity sessions like this place extra load on tissue and come at greater risk if injury. It is always a balancing act.
For many serious athletes, using HR to guide training programs is not often the preferred choice, nor is it the most accurate. However for many recreational athletes, when all you have is your watch and a heart rate reading, having some idea of the different effects of training zones may help you achieve more from your session and gain the appropriate fitness for upcoming events.
But remember…before you go embarking on any fitness program, particularly one where you will be using heart rate as a guide for training, you should have a full health check with your GP to ensure you are safe to perform your chosen activity.
Anthony Lance
SSPC Physiotherapist
References available on request.
