Heart Rate Variability (HRV) for Running

I'm a bit of a running nerd. I like to document what I'm doing. I do lots of heart rate training. I check my morning pulse/HR. I track distance, time, pace, elevation, cadence, weather, etc. I look at trends over time. Trends during a single run. If it can be measured, I've probably tried to track it! My newest addiction is heart rate variability (HRV). This is the variability between individual heart beats. In general, the more variability, the better. Very low HRV is a sign of over training, stress, illness, disease, etc. Several HR monitors can provide this data, I happen to utilize the Wahoo Tickr HR monitor. It's ANT+ and Bluetooth capable so it works with my Garmin watch and also several Android or iOS phone apps. I use the Elite HRV cell phone app. Here is a brief summary of HRV from the Elite HRV folks.

Resting heart rate is a great way to track recovery and over-training. Lower resting HR is good. Elevated resting HR is a sign of stress and needed rest/recovery. Similar data is correlated to heart rate variability (HRV), but in the opposite direction. A depressed (lower) HRV reading is a sign of stress and needed rest and recovery, while a higher HRV tends to be affiliated with fitness and readiness for a strong performance. Elite HRV app has you set a baseline and tracks you over time to provide a daily "morning readiness reading." You measure your HRV each morning (over about 2.5 minutes in a relaxed state) and it provides a "readiness score" from 1-10 (with a corresponding red-yellow-green status). It also tells you whether the reading is sympathetic (stressful) or parasympathetic (deep recovery mode) in nature. Perfect 10 is nicely balanced and ready to perform! I've tracked mine for just over 3 weeks and certainly find ups and downs that seem to be connected to tough workouts (like a long run or speed session), stress at work, or rested and recovered body. My hardest workouts seem to depress my HRV the most 2 days later (although my reading is slightly depressed after 1 day too).

I still need more data to really figure out what is happening with HRV and how it relates to stress, rest, and performance. I have yet to race since I've tracked HRV. One nice bonus is the software also tracks basic resting HR (low, average, high during the 2.5 minute readiness test). And it archives HR and HRV (plus mood and any notes you add). I can see this being very useful over time. I've already noticed a slight decrease in my resting HR (which is good!). I'm becoming more fit while I concentrate on aerobic endurance. I have a few more long runs before my July 31 marathon. It'll be interesting to see how my HRV varies with intense training...and racing. Will a hard marathon impact HRV more than a 50-mile trail ultra? What about a 5K? Tempo run? Intervals? More data is good, right?

Will this improve my training and racing? Will I be a better runner? Maybe. If I'm rested and ready to go (higher HRV), then I can push the workout. If HRV shows a lower reading, then I need to take it easy and rest or do a light active recovery run. There is some evidence that a program based on workouts that revolve around your readiness (based on HRV) have higher impact and better outcomes than a pre-defined workout program. Here's a snippet from a Competitor.com article:

The study concluded that, “The timing of moderate and high intensity training sessions according to HRV is more optimal compared to subjectively predefined training.” In other words, following a training plan out of a book or off of a website may not optimally improve performance. (Read more at "Can Heart Rate Variability Help Runners Optimize Their Training?")