The number of people in the fitness domain taking interest in heart rate variability (HRV) continues to grow every year. This term has gained popularity since the improvement in smartphone technology. HRV mainly represents the time variation between every heartbeat, also known as the R-R interval. This metric has been found quite helpful in training aimed at improving aerobic performance.
This metric has been found quite helpful in training aimed at improving aerobic performance.
Another application of HRV is predicting an illness in professional athletes. However, its ability to predict an injury requires validation. Certain technological advancements such as heart rate monitors, smartphone applications, and finger-wave pulse sensors have been found to measure HRV quite accurately. The precise HRV measurements can be performed in ultra-short durations in a seated, standing, or supine position.
What is Heart Rate Variability (HRV)?
The popularity of the term HRV continues to increase, thanks to its association with athletic performance and recovery. This popularity is also due to the development of smartphone apps that use this metric to help athletes analyze their performance.
HRV has originally been measured using an electrocardiogram (ECG) in the past. However, it can now be measured using a finger-wave pulse sensor or a heart rate strap. The most common and reliable metric used for measuring HRV is the root-mean-square difference of successive normal R–R intervals (RMSSD). This HRV measuring protocol is more prevalent in practical sporting environments.
Another application of HRV is in the medical environment. It is generally used for predicting mortality after a cardiac attack. It is also a powerful metric to help with the diagnosis of certain conditions such as congestive heart failure, depression, diabetic neuropathy, post-cardiac transplant, SIDS, and poor survival in premature babies.
Significance of HRV for Athletes
In general, HRV acts as a tool to help you measure your trends in fitness, readiness to compete, and fatigue. HRV mainly provides a set of values when you use it to measure your performance. A higher value generally represents an overall better functioning nervous system, which reflects your body’s ability to react to stimuli and make micro-adjustments consistently.
On the other hand, lower HRV values are a sign of a fatigued nervous system. This may mean an overall sluggish response of your nervous system when a stimulus is introduced to it.
Interpreting Changes in HRV
Here is a list of some common interpretations of HRV changes.
- An increase in HRV with a decrease in RHR (resting heart rate) is a sign that your heart is doing well with the athletic training you perform.
- An increase in HRV with an increase in RHR represents accumulated fatigue unless it happens at the start of a short training block.
- A decrease in HRV with an increase in RHR also signifies accumulated fatigue unless you are tapering.
- A decrease in HRV with a drop in RHR generally signifies prolonged low-intensity high volume training, which could become a sign of an overtraining state if not reversed with appropriate rest.
In some cases, HRV values can decline for a couple of days after you an intense workout or a race. And an increase in this value is seen in athletes during times of illness. This is mainly due to the immune system going into overdrive. Hence, it is necessary to understand the way HRV may change day to day on an individual level. All this may portray HRV as a tricky metric but not when other measures are brought into the equation.
Using Heart Rate Variability More Effectively
If you want to use heart rate variability as a tool to measure your athletic performance, you will have to consider the following factors.
HRV measurements work best when you run them regularly to get a good number of readings. As stated above, occasional low or high readings do not represent the true values. You will have to get various readings to perform accurate interpretations.
Note your HRV readings when you wake up in the morning
Waking up in the morning is enough of a stressful event to test your nervous system. Your nervous system won’t be up to the mark if you are fatigued. And therefore, the HRV readings you get with an active nervous system and the ones with a fatigued system are going to be different.
Take readings frequently
Evaluating trends over time is the most accurate way to use HRV. Many HRV-based smartphone applications show their evaluations after consistent readings. These applications interpret those evaluations based on slight changes from your normal baseline. Hence, consistency is the key to using this metric if you want to get the most accurate results. For this purpose, you have to make sure that you measure your HRV every day, at the same time, and in the same position to avoid any unnecessary variations in the daily readings.
Use HRV with other metrics
Like many other training metrics and also due to being somewhat tricky, HRV yields better results when used with other information. Information that you might need with HRV includes training load, resting heart rate, and sleep quality.
Adjusting the measures’ length in time
It is generally recommended to choose a longer duration of the HRV measure. Many applications use 1-minute reading or 5-minute reading. With longer readings, you get more accurate data. In some studies, researchers have even used 10-minute readings to get more accurate information.
Advancements in smartphone technology have allowed for more accurate fitness tracking and analysis. More specifically, cellphone cameras on this day use photoplethysmography, an effective tool to assess HRV. You can also add extra gadgets – like heart rate monitor chest straps – to the system to measure your HRV even more precisely.
So, should you use HRV for sports analysis? It really boils down to whether or not you are ready to commit to consistent data collection about your heart rate variability. This measurement is not for you if you can manage only sporadic measurements.