Sometimes it can be tough to gauge when it’s the right time to push yourself and train hard, or when it’s best to take it light, or focus on a stretch and reset session.

Training hard on a regular basis can leave us a little stiff and sore, but it’s good to push through it, right?

…Not necessarily!

Here’s why.

While we might feel as though we’re getting closer to our fitness goals by toughing it out through the low days, we could actually be doing damage to not just our bodies, but our training progress as well!

By working out of sync with our body, we are going to be either:

1. Doing ourselves damage by overtraining, or
2. Minimal progress and performance by undertraining.

Having a variety of light to hard training sessions is the best way to challenge our systems, because rest and recovery is where progress from training is made. Without sufficient rest and recovery, the body and mind becomes tired and stressed, and this is when most injuries occur.

How do we know when to train hard or to rest and recover?

By determining our Heart Rate Variability (HRV).

What is Heart Rate Variability?

We all know our hearts pump blood, carrying oxygen and nutrients to the parts of our body that need them most. A strong heartbeat pumps a lot of blood and a weak heartbeat pumps a little, so it’s safe to say we all want a strong heartbeat.

While many athletes monitor their heart rate when training to determine their Heart Rate Training Zone, less people know that the intervals at which they beat, can vary a lot, or vary a little.

This is called our heart rate variability or HRV, and what it does is show us our heart’s ability to adjust, and perform, in different situations.

• A heart rate that has a steady rhythm with similar intervals between each beat (RR intervals), has a ‘low’ HRV.

• A heart rate that has varying intervals between heartbeats, has a ‘high’ HRV.

It’s good for athletes to have a high HRV, because the heart is able to adjust how much blood it pumps around the body, depending on the intensity of the training.

However, too much variability or instability may be a sign of arrhythmias or nervous system chaos, which has a negative impact on overall body functioning, and the efficient utilisation of energy.

Variability that is too low is an indicator of age-related frailties, disease and incorrect functioning of assorted self regulatory control systems.

The Science

HRV researchers state in this journal article,

“HRV is an important method for assessing cardiovascular autonomic parameters that are partially under the regulatory control of innervations from the sympathetic and parasympathetic systems.

These two components of the autonomic nervous system (ANS) balance between them affects the consistency in the time between heart beats…”

The Autonomic Nervous System

…controls the functions that we cannot consciously direct, such as the heartbeat and digestive processes.

The Sympathetic Nervous System

…prepares the body for action, such as, increasing the heart rate.

The Parasympathetic Nervous System

…conserves energy, such as, slowing down the heart rate.

Measuring our HRV indicates to us how well our sympathetic and parasympathetic nervous system works. The higher our HRV, the better our bodies can ramp up performance and the better our bodies can slow down and recover when we need them to.

What determines HRV?

Heart rate variability is different from person to person and is based on fitness levels, mood/stress levels, gender and age. However, HRV generally fluctuates depending on the stress levels in our mind and body.

After continuous daily training without rest, or after an intensive training session, our bodies are under stress and our HRV will most likely be low. However, if our minds are stressed due to a stressful lifestyle or a worrying situation, lack of sleep or dehydration, HRV may also be low.

Consequently, when you’ve had quality sleep, a rest day or a low stress day, it is more likely that your HRV is going to be high and this means that during your session, you will be able to reach your full potential without fear of injury.

There are other factors that can also contribute to your HRV, such as drugs and medication, as well as stimulants, like caffeine.

The benefits of tracking HRV

By measuring our heart rate variability, we take the guesswork out of how we need to train.

Knowing when we should train hard

If we have a high HRV reading, this means we are ready to do a serious workout. We know our systems are working at their optimal performance and pumping blood effectively around our bodies. Therefore, we are able to push hard, and our bodies should be able to do what we want them to do.

When we should rest and recover

If we check our HRV and it is low, we might decide to take a rest day, train at a lower intensity, do some stretches, take a yoga/pilates class or something similar. Without these adjustments, the risk of illness or injury from our current training routine will be quite high.

Write optimal training programs

This method allows us to have full control of training. We can screen for optimal performance, write our training programs knowing when our bodies will be in a well enough rested state to push harder and when we must allow ourselves to have a light recovery day, or even a full rest day.

Image: Training hard when you are already stressed (low HRV) can result in injury.

How to measure HRV

Heart rate variability should be tested consistently, everyday, at the same time (usually in the morning), with the same method, for the same amount of time (1-5 minutes).

Here are a few different ways HRV can be measured:

Subjective Measures

Subjective measures, such as Rate of Perceived Exertion (RPE), Timed Sessions, Repetitions and Distances Travelled, can be effective for gaining some insight into how you can get the most from each session. It relies on your own personal judgement of how you are feeling each day, based on the intensity of your training. If at any point you feel stressed and overtrained, you may have a low HRV and may decide to have a rest day. However, this method leads to an often inaccurate estimation of exactly what intensity you should be using for the maximum benefit from your training session.

Heart Rate Monitor and Mobile Application

More recently with the prevalence of mobile devices HRV has become much easier to track. It is now possible to purchase specialised heart rate monitors that fit easily around your chest, which syncs with an app that can be downloaded to your phone to track your readings. Apps such as Ithlete, Bioforce and SweetBeat are commonly used. They require a compatible heart rate monitor band which indicates that as far as their measurements go, they are likely to be much more accurate. There are also a variety of apps that do not require any additional hardware to function. They include Elite, HRV and HRV4Training with many more options out there to suit a variety of needs. Each of these apps can run on Android, Apple iOS or both.

Simon Wegerif, founder of iThlete says,

“HRV is so accurate that you can essentially override your intuitive signals”.

Image: Elite HRV Desktop and iPhone app

As with anything, it pays to shop around and have a thorough look at what is available and will suit your needs before committing to any specific app, especially those that require the added expense of hardware.

Stress Check App

A much cheaper, but less accurate way to measure HRV is through a stress check app. Most mobile devices tend to have some form of this on both iPhone and Android platforms. The concept is similar to using a heart rate monitor and an affiliated HRV program, though the algorithms applied are nowhere near as complex. What it does is measure your heart rate and then calculates a percentage measure of stress levels. This may lead to a more generalised reading. However, when used consistently over a number of days it is possible to track your stress patterns and apply it to your training days. Days where stress readings are higher, it may be sensible to train lighter, alternatively when your stress levels are lower, it is an indicator that you can train at a more intense level.

Electrocardiogram (ECG)

This is the equipment used to measure HRV, which runs off a series of algorithms to accurately measure exactly when your HRV is high or low. It consists of attaching little sensors, called electrodes, to various parts of the body and the person having to lie down and rest for 10 minutes, do exercise on a bike or treadmill for 10-30 minutes and move around normally for over 24 hours. While it is accurate, it is very time-consuming and definitely not practical.

Image: Example of an ECG reading

What this means for athletes

The more we become attuned to the patterns and cycles of our body, the better chance we have of achieving the results we want. Nobody wants all those hours, days or even years of pushing hard every training session, to find out that they have been misreading their body, and ultimately stressed out and injured! By giving ourselves the opportunity to calm and relax our minds and bodies, we increase our HRV, which is massively beneficial for our training.

If you want to start measuring your HRV, make sure you plan it well, do it consistently and do your research, by asking yourself some of the following questions:

• What are my training goals?
• What benefit do I want to gain from tracking my HRV?
• How is measuring my HRV going to increase my output as well as my recovery?
• What method am I going to use?
• When am I going to check my HRV?

The application of tracking HRV within the fitness industry is still fairly new and the long term benefits have not yet been recorded. However, in the short term, there appears to be great benefits in increasing the overall awareness that an athlete has within themselves, and there is a direct correlation between this and increases in performance. Like the wise philosopher says…

Research what products and methods are out there, and learn about yourself and your body. It will only make you more aware and intuitive. There are a multitude of online options to gain an insight regarding what products are available, you can even talk to your trainer, doctor or qualified health professional.

If you want to get the most out of your training, check your HRV consistently, and adjust your lifestyle and/or training program accordingly.

Train intelligently and rest well!