Did COVID Erase My Endurance Gains?
Shortly after I published my last post, I got COVID. How much of my training progress did I lose?
![A cyclist being engulfed by COVID-19](/content/images/size/w2000/2023/01/bmca_a_cyclist_racing_against_a_COVID-19_cell_also_riding_a_bik_8a28282e-8324-48e2-9527-f76b80c47f83.png)
Shortly after I published my last post, I got COVID.
The virus knocked me out for a full week, and even after I was “better,” I didn’t feel like myself. I was fatigued late in the day, and I had a very hard time getting out of bed in the morning.
I eventually returned to training, but my experience left me wondering: How much of my training progress did I lose?
In my last post, I identified an interesting metric that seemed to track my novice gains in endurance training: the amount of energy generated with each heartbeat, measured as watt-minutes per heartbeat.
Let’s look at that metric before and after my COVID break.
![](https://www.benmcallister.com/content/images/2022/07/pHR_June25.png)
This looks like good news! My heart looks about as efficient at generating energy as it was before COVID. On the other hand, this metric seems suspiciously high. I certainly felt less fit than this chart would indicate.
Any time you are looking at a ratio, it pays to look at the numerator and denominator individually to see the full picture. (In a subscription app, for example, conversion—or sales efficiency—matters, but so does total sales.) So let’s look at the components of the above ratio: power and heart rate.
![](https://thegreatlevelerblog.files.wordpress.com/2022/07/median_power_june_25.png?w=737)
![](https://thegreatlevelerblog.files.wordpress.com/2022/07/median_hr_june_25.png?w=737)
These graphs tell a broadly similar story as the ratio in the first graph. Heart rate is a little below average, while power at or slightly above average. This sheds some light on the ratio, but it’s not a “smoking gun” that points to an obvious loss of fitness. However, it’s important to note that both of these metrics (power and heart rate) are also ratios.
- Power is also a ratio of energy generated (or consumed) over time.
- Heart rate is a ratio of beats per minute.
So the missing piece of data—the missing denominator—is simply duration: How long were my rides?
![](https://thegreatlevelerblog.files.wordpress.com/2022/06/duration.png?w=737)
In fitness, the simplest data is often the most meaningful. My training is clearly not where it was in mid-April. There are two lessons here:
- Beware of focusing (exclusively) on ratios.
- Success in any domain is difficult to boil down to a single metric.
Pushing beyond these basic lessons, what is the theory of cardio fitness that explains the rapid increase in my watt-minutes per heartbeat early on, and yet also accounts for its apparent “stickiness” after COVID–when I would have expected a total reset? One theory is:
- Novice gains (measured with my original ratio of watt-minutes per heartbeat) can be “sticky”, persisting after an illness and gap in training.
- The “top end” of endurance can be lost more easily with a break in training.
We often discuss fitness as if “one size fits all.” The impact of training—or lack of training—is not universal, but depends on how advanced a particular athlete is. In my case, I’d say I’m “barely post-novice” as an endurance trainee.
Which makes the answer to the question posed in the title of this post a decisive “sort of.” COVID didn’t entirely erase my novice gains. But I clearly have some endurance rebuilding to do.