Heart Rate Variability (HRV): What It Is and How to Improve It

Researchers at Harvard University have gone as far as to say that measuring your Heart Rate Variability is “a visual insight into the most primitive part of your brain” which sounds great but how can us fit folks use it to our advantage?

Brock Armstrong
9-minute read
Episode #411

A few weeks ago, listener Megan wrote to me on Facebook and said: "Hey Brock, would you explain heart rate variability (HRV) in layman's terms? I've heard a lot about it, but don't quite understand the concept or its use." I thought that was a great suggestion because HRV is a technique that has been growing in popularity and acceptance in the sport and fitness world. So here you go, Megan: HRV 101. 

Most athletes know that getting enough rest after exercise is essential to performance. Still many of us overtrain and feel guilty or lazy when we take a day off. But relentless training can break even the strongest athletes and rest is a necessity to allow your body to repair, rebuild, and strengthen.

Given that it is so difficult for many of us to know when to train hard and when to back off, before we strap on a bluetooth heart rate monitor and fire up our HRV measuring smartphone app, let’s look at some non-HRV ways that we can measure our current state of recovery.

Measuring Workout Recovery

Resting Heart Rate

Sports scientists have confirmed a link between fluctuations in your resting heart rate and overreaching or overtraining. But this link is not easily understood nor directly correlated. Many factors get in the way of it being 100% reliable. 

But still, measuring your resting heart rate first thing in the morning is a good place to start. Keeping in mind that day-to-day variations in resting heart rate of approximately five percent are common and are not warning signs. However, increases of greater than five percent are typically a sign of fatigue or overreaching from too much intensity. A decrease of greater than five percent is often observed in cases of too much exercise volume. 

Sleep Quality

Having trouble getting to sleep at night, tossing and turning throughout the night, and waking up much earlier or later than usual can all be signs of inadequate recovery.

Sure a restless night can simply mean you didn’t eat enough after a workout, it’s too hot in your room, or you have too much on your mind, but it can also mean that you have depleted the anabolic hormones important for muscle repair and recovery or that you have too much cortisol production. Like resting heart rate, this can be hard to interpret and correlate directly. 


If you are not getting hungry the way you normally would, it can be a sign that you are under-recovered and need a day or two of recovery.

Your appetite typically decreases with under-recovery, high training load, and fatigue. And this can create a vicious cycle—a cycle that results in consistent negative energy balance and subsequent amino acid, fatty acid, and hormone depletion.

Amount of Muscle Soreness

DOMS (delayed onset muscle soreness) is a completely normal reaction to high training intensity but can increase your risk of injury if followed by insufficient rest and recovery.

Persistent muscle soreness is one sign of overreaching and overtraining. While in some phases of training, you should expect some DOMS, it should not be a chronic condition.

General Energy Levels

We have all experienced those days when we didn’t want to train but ended up having a fantastic workout. We have also all had those days when we didn’t want to train, so we didn't, and felt much better for it. The trick is to be able to distinguish low motivation from under-recovery and low motivation from non-physical factors, like laziness or being stressed after a tough day at work.

A good way to gauge this is to simply start your workout, get through the warm-up, and then see how you feel. If you’re still tired and dragging-it after the warm-up, you are likely under-recovered and need a day off.

General Mood

In the sports world, POMS (Profile of Mood States) first gained favor among sports psychologists in the late 1970s. Recent research confirms the link between recovery of the mind and recovery of the body, as well as the impact that your mental state can have on recovery. This explains why general apathy, feelings of depression or anxiety, and mood swings often indicate fatigue, impending illness, or under-recovery or overtraining. These markers are also commonly associated with periods of underperformance at your chosen activity or sport.


All content here is for informational purposes only. This content does not replace the professional judgment of your own health provider. Please consult a licensed health professional for all individual questions and issues.

About the Author

Brock Armstrong Get-Fit Guy

Brock Armstrong was the host of the Get-Fit Guy podcast between 2017 and 2021. He is a certified AFLCA Group Fitness Leader with a designation in Portable Equipment, NCCP and CAC Triathlon Coach, and a TnT certified run coach. He is also on the board of advisors for the Primal Health Coach Institute and a guest faculty member of the Human Potential Institute.