Heart Rate Variability

Thanks again to Phil Maffetone, I discovered a great training tool: heart rate variability, abbreviated as HRV. In his Big Book he describes a tool for measuring HRV that any athlete can use right away. I tried it last summer and was impressed. In short, it works, and can give valuable feedback that will help keep you honest when evaluating your training.

What is Heart Rate Variability?

Everyone knows that heart rate is not constant, that it changes minute to minute based on activity. That’s the reason for training with a heart rate monitor. But most people probably don’t know that beyond that, heart rate changes with every breath, even at rest. Heart rate actually speeds up on inhalation and slows down on exhalation. HRV measures how big this difference is. The more variability, the better. It shows that the body is well rested and governed more by the parasympathetic nervous system which promotes relaxation. When stressed, the HRV is low because the body is having difficulty “putting on the brakes” and is governed more by the “fight or flight” sympathetic nervous system.

What affects HRV?

All stress affects HRV, and its value relative to the individual gives a good picture of overall health. For athletes, training stress will affect HRV, so you can gauge when to push hard, (when HRV is high) and when to take it easy and recover. (when HRV is low) But ALL stress affects the nervous system and therefore HRV. Work stress, family stress, nutritional stress, and emotional stress of any kind will affect HRV. This data then gives a more complete picture of how the body is responding to the total life stress, not just training. But as aerobic training progresses, HRV gradually increases as fitness improves. Good rest, recovery, and stress management also improve HRV.

Who Uses HRV?

Hospitals have had access to this for decades using it get a clearer picture of a patient’s health. Professional athletes have been using it for awhile too. But because the cost has been very high, until recently regular folk haven’t been able to experiment with this great technology. Lately, as costs have down, it has been added to other forms of biofeedback for stress reduction.

How Do I Use HRV?

I take my HRV each morning as instructed by the developer. By tracking this score over time, I can see how my body is responding to all life stress. It goes up as fitness improves, and down if I’m under stress, sleeping poorly, out late, not eating well, etc. It helps me avoid overtraining or wasting time by giving me more good feedback besides subjective moods.

How Can I Get Involved?

I use the iThlete developed by Simon Wegerif of the U.K., but there are other available models. To use the iThlete, you put on a compatible heart monitor chest strap, plug the proprietary dongle into an iPhone or iPod Touch, launch the app, and follow the instructions. Couple this feedback with your training diary, and you can better plan your workouts and recovery days.