Breaking Down the Heart Rate Zones
In our last blog “The use of Heart Rate to benefit your training goals” we gave a brief introduction in the world of heart training and the many benefits associated with this training method.
Today we are going to dive a little deeper and give you a more specific look at the role heart rate training plays in relation to an individual’s own physiology and how training within a specific heart rate zone can create differing training adaptions.
Why heart rate monitoring is important!
For many of us, looking at a number of “beats per minute” on a heart rate monitor during exercise might not seem to mean too much.
As a number alone, it doesn’t, however by understanding how heart rate reacts to differing intensities, durations and types of exercise it can provide us with priceless information regarding how hard you are working, what energy systems are in use and the overall training adaptions that will occur.
Understanding how hard you are working during exercise, can be key to maximising each training session and improving overall performance.
Likewise, by monitoring each session through heart rate feedback, it can help us to avoid overtraining by ensuring we are working across differing zones, optimising all energy systems and not just training in the hard ones.
Heart Rate monitoring allows us to be efficient with our time and maximising our training adaptions to improve performance or actually work toward our goals.
What are energy systems?
There are three main pathways to generate energy during exercise.
These are:
- the Alactic (ATP-PC) system,
- the Anaerobic-Lactic (glycolytic) system,
- the Aerobic (oxidative) system.
When it comes to performing maximal intensity efforts (think sprints and explosive movements) lasting less than 10 seconds, we primarily use the Anaerobic- Alactic (ATP-PC) (adenosine triphosphate – phosphocreatine) system to generate energy.
For high-intensity efforts lasting upwards to 2 mins, we primarily utilise the Anaerobic-Lactic (glycolytic) system.
For exercise sustained longer than 2 minutes, our primary energy system in play is that of Aerobic (oxidative) system.
As you can see, the word “primary” indicates the dominant energy systems, however they will often work in combination with one another.
With varying intensities and duration, one system will tend to provide the bulk of the energy required to perform the desired movement or exercise, while another may may kick in. An example of this is interval training.
To assists athletes and coaches to train these particular energy systems, heart rates zones were created.
This allows instantaneous feedback on whether an athlete is in or out of the HR zone necessary to produce the required training adaption.
Each HR zone serves a specific purpose.
Depending on where you get your information from or who you consult, zones may differ slightly.
To get a more accurate and individualised heart rate zones, performing a VO2 max test is considered gold standard.
At Fighting Fit we have all our athletes complete a VO2max test, if conditioning training is a requirement of their training plan.
The Main Heart Rate Zones
Depending on who you talk to, coaches, strength and or conditioning coaches, zones can vary somewhat from 3 to 5, then sub zones within each.
It can be a bit confusing for the average punter, but has the potential to be very specific for the athlete if used correctly.
So let’s keep it simple!
A break down of 4 zones from a VO2max test showing heart rate, thresholds, calories and recovery results.
Zone 1
Color: Blue
Aim: Recovery and/or Fat Burn
Intensity: Sub 50% for light recovery up to 70% HR Max for Fat burning
Feels like: Very easy to Light
Exercise within this zone, has a number of purposes from warming up the body for high intensity activities, cooling the body down after tough workouts or aiding recovery.
The intensity level within this zone, is one that could be maintained for long periods.
Fat is typically the main source of energy within this zone, making it great to assist fat loss in people who struggle to perform high intensity exercise.
Research suggests performing an active recovery session in this zone aids recovery from high intensity sessions.
Tip: most people write this zone off as boring and useless, however it is so very important as it aids fat use, restores our body following high intensity exercise.
A strong blue zone increases our recovery times where high intensity interval type work is required for sport.
Zone 2
Color: Green
Aim: Improves Aerobic Fitness
Intensity: 71% – 80% HR max
Feels like: somewhat hard, but can talk comfortably through out.
Exercising within this zone should be conducted at a greater intensity than zone 1, but again should be performed at a pace that can be sustained for long periods.
Due to the slight increase in intensity, we see a shift to a more mixed delivery of energy from fats and carbs.
The result of training within this zone, can increase growth hormone, and allows the body to better regulate oxygen/carbon dioxide delivery and removal from working muscles.
If done regular this can result in improvements to the aerobic fitness, improved capitalisation of muscles for oxygen delivery resulting in a greater ability to recover between efforts and perform higher levels of total work.
Tip: long sustained duration (LSD) of exercise in this zone is highly effective for endurance type sports as it below threshold and where we use fat and carbs to fuel us.
However if greater the 60-90mins in duration, we will need to replenish our glycogen (carbohydrate) stores to continue or prepare to decline in performance.
Zone 3
Color: Yellow or Orange
Aim: Lactate threshold
Intensity: 81% – 90% HR max
Feels like: Hard, it’s a struggle to talk!
Zone 3 is the most common for lactate threshold training.
This zone represents the first zone that includes both aerobic and anaerobic energy delivery.
An athletes “lactate threshold” is the point where when crossed the body begins to anaerobically generate ATP (energy) and produce (bioproduct) lactate faster than the body can clear out or utilise for energy.
If exercise is sustained for long enough, we will classically see the performance of the person begin to decline, or depending on the level of conditioning cease as it is too uncomfortable to continue.
This is that heavy legs and cant keep going feeling.
Types of training within this zone, are often represented in the form of tempo or interval-based training above to below threshold (see below).
In a well designed program, you can increase your lactate threshold or train to perform a greater amount of work in this zone by improving the efficiency of this energy system.
Tip: Lactate is often seen as the devil, however lactate is used as energy to muscles and your organs. It is an amazing process!
But remember it is a higher stress activity and adequate recovery is required to improve performance.
An example of some threshold intervals where recovery time has come down over time and in line with the energy system demands of the sport.
Zone 4
Color: Red
Aim: Cardiac Power
Intensity: 90% – 100%+ HR max
Feels like: Death ;-), Extremely hard, your more concerned with surviving then talking.
Often referred to as the “red zone” (hurt zone), exercise within this zone can only be sustained for short periods, often less than a minute. Unless you extremely well trained and conditioned.
The types of exercise most commonly performed within this zone is High-intensity interval training (HIIT).
An example of a HIIT session would be to perform all out maximal efforts for 30 to 90 seconds achieving peak heart rates.
With much longer rest periods required, 3 to 5+ minutes is in order to reproduce the same power or work output to get the gains for this type of training.
Athletes or individual training within this zone, need to be aware that they ensure adequate recovery and adaptation periods, as it is very stressful upon the body.
Prolonged and/or repetitive use of this style of training without adequate recovery in a poorly designed program can cause overtraining.
The main physiological adaptions seen from training within this zone includes improvements to VO2 max, muscle strength/power and increased stroke volume in the heart to name a few.
Tip: 1-2 sessions per week is plenty to reap the rewards of this zone!
An example of some intervals on the assault bike performed from the green to yellow zone.
Ultimately zone training is a very individualised training concept and will vary significantly based on the needs and requirements of the athlete or individual utilising it.
For more information or to get started training with heart rate training consult us for a specific and completely individualised training plan to meet your needs.
Chris Hunt is Fighting Fit’s Clinical Exercise Physiologist, Sport Scientist and Strength and Conditioning Coach. He has a special interest in enhancing physical performance in everyone from athletes to elderly.
