Technology such as heart rate monitors and power meters help us fine tune our training efforts on the bike. However, knowing how our bodies are doing off the bike is equally important. We have technology to measure this called HRV or Heart Rate Variability. Sleep, diet, and training load impact how we recover, and HRV helps us measure this. Interestingly, HRV derives from Chaos Theory and is very important in medicine; a low HRV is good a predictor of heart function following a heart attack. In sports, a low HRV can be a sign that the body is over trained and needs a break.

What is Heart Rate Variability?

HRV is the physiological phenomenon of variation in the time between heartbeats or the beat-to-beat time interval. Simply, it measures the time variation between heartbeats and produces a number we call HRV. Changes or variances in the time between our heartbeats can be used to determine how well our body is equipped to handle physical exertion.

When is the best time to measure HRV?

The best time to measure HRV is in the morning when you wake up. It only takes a couple of minutes and be sure that you are in a consistent state, versus moving around or starting and stopping activities. It is important to maintain the same procedure, posture and routine in taking the measurements as environmental factors can affect the reading.

What can HRV do for you?

A high HRV is a good signal that your body has properly recovered and can respond to stress. For cyclists, this means your body will be able to handle increased training loads needed for long or hard workouts. It is well known that individuals who exercise regularly have a ‘training bradycardia’ (i.e., low resting heart rate) and generally have higher HRV than sedentary individuals.

A low HRV, on the other hand, can indicate mental and physical stress often associated with overtraining. While the body usually shows signs of soreness or fatigue, your heart rate will change too—often becoming harder to elevate during intense efforts on the bike. More rest and recovery are needed.

How to trainers / coaches utilize HRV in their training?

Athletes / Trainers to sometimes take multiple measurements of HRV depending on the situation. If overtraining / under-recovery is suspected, then HRV will be taken two or three times a day. Generally, HRV is kind of like a traffic signal. Green is go, orange means proceed with caution, and red is come to a complete stop. Green might be 90, Orange might be 80, Red might be 60 – depending on the individual. When the readings are good, you’re in the green zone and are ready to train, can handle activities of daily life with ease and might even be in a better mood. If your goal is to decrease stress, then shoot for green as much as possible. In the morning, in the afternoon, and after a workout would be a realistic example.  The measurements must be consistent and not around a lot of extraneous activity.

Besides recovery, HRV is used by athletes to hint if they are becoming sick. This is typical when the athlete’s repose to environment and training deviates from the normal response.

For an elite athlete, what’s considered an ideal value? For a non-elite athlete?

There is no set range for HRV because it is unique to each individual. A fit athlete tends to have an HRV score above 70, and if it drops below 60, it’s often a warning sign. A non-elite athlete may have a score in the 60’s. But, the best way to create your baseline for ongoing measurement is to track your HRV daily upon waking for a few weeks. You will begin to see patterns and ranges emerge, and these become your parameters. That being said, usually a HRV in 80’s or above is considered ideal. Regardless, there are general guidelines to take into consideration like gender and age, it must be emphasized that everyone is different.

Can HRV values be wrong?

Yes. If a person has a history of skipped heart beats, the HRV reading is null and void. The HRV measurement assumes that you have zero skipped heart beats.

How does a trainer/coach use HRV? What do they look for?

Context is king here. Generally, trainers look for a trend in values.  They also look for changes in HRV relative to change ups in exercise routines and even dietary patterns. Long term trends are often more important than daily variation; although strong variations in high and low values must be taken into consideration. In addition, HRV also depends on the sport and stress load. For example, an endurance athlete with the same HRV as a power athlete might be interpreted very differently.

What is the best practice on how to utilize HRV? Baseline measurements? 

Best practice is to keep it as simple as possible. HRV should be measured every morning upon waking up. Building an individual database of values can let the person know where they are at in terms of training and what normal may or may not be.

What product is considered ‘state of the art’ – most accurate/reliable? 

The Polar heart rate monitor is considered by experts to be the best for measuring HRV. In modern phones, PPG (photoplethysmography) methods using the camera have recently been shown to be very consistent with heart rate strap readings.

What’s most important when measuring HRV?

The most important aspect of HRV is consistency. If an athlete has a big training block, HRV is something can help the coach / athlete make a decision to push harder or pull back or engage in active recovery.

How do you optimize Your HRV?

Diet – Eat a real foods diet that is tailored to your goals and athletic performance. If there are known food sensitivities, HRV can be affected. Strong dietary changes can substantially influence the readings.

Exercise – HRV is one measurement that can help you plan your daily activity level and your training. When it comes to exercise, more is not always better. If your HRV indicates that you need to slow down or take a day off, consider taking a day off or going for a lighter workout. It’s not a standalone measurement, so go ahead and train if you’re feeling great even with a low HRV score. In addition, if you train at different times in the day, timings of the training sessions the day before are important to consider when interpreting morning readings

Lifestyle – HRV can strongly reflect stress in your life. No one can live a stress-free, but you can avoid unnecessary lifestyle stressors. HRV may be something that triggers you to reevaluate your lifestyle. Sometimes it is best to focus on your most important goals.

Sleep – Getting quality sleep is probably the most important factor that affects HRV. Getting a solid 6 to 8 hours of uninterrupted, deep sleep has been shown to be very important for recovery and is usually reflected by positive HRV readings.

Incorporate holistic exercises like yoga and tai chi. These activities can help lower stress through breathing techniques and relaxation. It can also help you with core strength, so you won’t have to look at a day off the bike as a total “waste.” If yoga isn’t your thing, then schedule a massage, which can have similar positive effects.

How to Adjust Your Training According to Your HRV

Knowing your HRV can help you train more efficiently, and avoid the negative effects associated with overtraining. While a scheduled training plan can be a good thing, what makes one training plan better than another is flexibility. Knowing your HRV will only be useful if you’re willing to adapt your training according to your biometric results.

The first few months will be more difficult to set a training plan in stone—but once you start to see patterns in your HRV levels, you’ll become more aware of how long it takes your body to recover properly between hard efforts. This will make setting up future training plans easier to manage.

Since a high HRV is a good indicator that you can proceed with your training as planned, adapting to a low HRV can be harder for some cyclists to deal with. What a low HRV doesn’t mean is that you need to shut things down completely—but you will need to adapt your workouts, especially if you’ve have intervals or another hard workout on the schedule. A few questions you should consider when you notice low HRV measurements include:

Are you under more stress at work?

Has your training routine changed?

Are you increasing your mileage or number of hard efforts per week?

How much sleep are you getting?

Are there other new stressors in your life?

Tips for Using HRV

Like any other technology, there will be a learning curve when incorporating HRV technology into your training regimen. Here are a few tips to consider:

Use an HRV app.

There are tons of new apps that will crunch the numbers and make it easier to interpret the results. In addition to the purchase of the app, you will also need a heart rate strap and a specific heart rate strap.

Popular options available for download on a smartphone or computer include:

Sweetbeat

Omegawave

Azumio Stress Checker

Myithlete

 

Special Thanks to Allessandro Ferretti and Peter Defty