Updated: Feb 21, 2019
I started doing some serious swim training in mid-November. To monitor my training progression, I take my Heart Rate Variability (HRV) every morning upon waking. As you can see here, the blue/teal horizontal trend line back then was relatively narrow ranging from a 7.2 to 7.7 HRV score*. This was my normal range of being able to adapt to stress. Any daily score above or below this narrow range of normality would suggest that that day’s workout may not be performed where I would like. After 13 or so weeks of hard training, you can now see the detected trend has widened ranging from 7.2 to 8.1. This is good as now I have a more robust ability to train at a desired level despite daily variations in stress**. After weeks of training, my new normal is ‘wider’ and I can still perform despite normal fluctuations in daily life stress.
But, the increased ability to handle stress came at a minor cost – I had to endure a few bad practices. As you can see, I was experiencing positive adaptation up to the 25th or so. In the week between Christmas and New Year’s, I experienced some parasympathetic saturation (maybe due to having some days off of training during the holidays, but the exact cause is unclear).
After the holidays I was back at training hard. Around January 12th, however, I started to possibly negatively adapt to training as seen in this colorized version here –
The yellow bars suggested I was experiencing some maladaptation to training. Colorization simply means that there are changes in my physiology. Colorization doesn't necessarily mean that I can't train that day or I'm going to have a bad workout. There are many factors that go into physiological adaptation and training stressors are just one of them. The red bar suggested I was falling into overtraining. I was also feeling 'off'. One workout during those days I simply got out after a few minutes into the first hard set because I was performing so badly. My motivation was also scoring low during that time. I took three days off and allowed my body to rest, did some yoga, and hoped the following week my physiology could return to normal. From January 20th to February 15th, I was riding the line between overtraining and progress. I did experience some minor improvements in fitness but nothing major. On February 15th, I took some planned rest to prepare for a competition. You can see my physiology responding positively to that planned rest.
While monitoring my long-term HRV trends and suggestions during a few 'bad' days of training (and other variables such as motivation level), I was able to adjust my training so that my physiology became more robust (wider trend line) which allows me to take on more variations of stress without serious performance decline in the long run.
My bad workouts weren’t bad at all. I was able to know when possible maladaptation to training was occurring, prevent any further dips into overtraining, take measures to correct my training, and confirm that those bad workouts were indeed helping me. There is currently no other way to non-invasively quantify training unless you are measuring HRV each day. That’s powerful.
* Each gray bar represents each day’s heart rate variability score
**Stress is cumulative. The brain will monitor all forms of stress – life, training, poor nutrition, poor sleep – and dictate how well you can train.