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A lesson from the pandemic…
It pays to be cautious after a suspected viral infection.
Related, given that endurance athletes are higher risk for atrial fibrillation1, managing heart stress (after viral infection) seems wise. As athletes, we have a lot to lose if our long-term health is impaired.
Most of the time we don't have positive confirmation of what we've caught, but the signs of stress are there.
Today, we’re going to start with Gordo sharing his approach to managing cold & flu season. We will finish up with Doc Hellemans’ advice.
While this article will end with “the doctor’s” advice, you should start with a visit to your doctor.
Ideally, a sports doc with experience helping athletes get, and stay healthy.
Using HRV For Illness - Gordo
I follow a recovery on demand protocol with no preset recovery weeks.
I explain the protocol in my article called Dead Simple Loading. My loading system has four components:
Morning Resting Heart Rate (AM RHR)
Evening Resting Heart Rate (PM RHR)
How I Feel
Back-To-Back Easy Days, Weekly
When I measure morning resting heart rate, I collect heart rate variability (HRV) data. For a detailed explanation on HRV please refer to Marco Altini’s Guide to Heart Rate Variability. I use Marco’s apps to capture my heart data.
I have found HRV to be a reliable indicator when I should “not-load.”
In other words, suppressed HRV is a reliable “negative signal.” Lower than normal HRV indicates I should back off.
In the picture below, I want you to notice the scale of the HRV drop. My HRV falls out of my normal range before I feel symptomatic.
Let’s compare the HRV response to my morning resting heart rate.
Initially, RHR elevates but it’s only a few beats and, given I feel great, easily ignored.
The biggest heart rate pop doesn’t happen until I’m well into my illness.
Your watch might already be capturing your HRV status. Below is my HRV status captured by my Garmin watch. If you are using Garmin data then click “overnight average” to see the daily average (dotted black line below).
Marco has written an article about the differences between, and different uses for, overnight versus morning HRV data.
Why is the above useful?
When I caught covid, there was no guesswork.
In the space of 12 hours, I was descending into illness.
This was confirmed the next morning with a rapid test.
I had no desire to train.
Most illness are not like covid. More usually…
I get a respiratory infection of unknown type.
I back off.
My body feels great from dropping load.
I'm tempted to get back to training.
This is where HRV helps.
Post-infection "stress" shows for days after I'm feeling fine.
Stress shows in:
Elevated Resting HR
Suppressed Morning & Overnight HRV
In my post-illness phase, I follow John’s advice. If I feel good then…
Zone 1 / Easy training at a reduced duration.
Strength work, with longer than usual rest intervals.
By backing off quickly, the illness remains minor and I can do light activity. This does wonders for my mood and productivity.
Here’s where “recovery on demand” works great.
It does not matter “why” my metrics have tanked.
I take extra rest, usually only a couple easy days.
If it’s nothing then I’ve rested a bit more. No big deal.
If I get sick then, hopefully, the severity and the duration of the illness is reduced.
By backing off early, I “lose” 4-7 days for a minor illness. It’s more of an inconvenience than a major loss of fitness.
If I don’t back off early then:
The likelihood of a major illness is increased
I have 10-14 days where I’m grinding through, not feeling great and not improving.
But there’s more you should be aware of…
In this most recent illness I had a slight fever.
John advised me to be watchful for the next 2-3 weeks.
Below he explains…
Doc Hellemans’ Experience
The post-viral recovery period covers more than loss of fitness, like after a break.
Return to fitness after a break is reasonably similar for all athletes, with slight individual differences, e.g. heavier build athletes take a bit longer to come back.
The time it takes to return to fitness following a viral illness fluctuates wildly between individuals and is unpredictable. Here ongoing monitoring is required.
Above Gordo mentions HR and HRV. I prepared the following HR guideline table for my article on The Tired Athlete, which can also be used by the athlete who recovers from a viral illness as fatigue is usually the main issue
There are special circumstances which can cause a physiological change in heart rate response. Hot conditions and altitude can increase the heart rate response significantly. Cold conditions are more likely to suppress the heart rate response (until the body has warmed up).
A viral illness with no fever (e.g. the common cold) has a much shorter recovery time than when the athlete has suffered a febrile illness. Fever tends to have a profound effect on the body’s functioning, especially in relation to exercise, which can last much longer than the time of fever.
I have seen many times that athletes who suffered from a viral illness in the weeks before an event feel seemingly recovered from their illness and back to normal training, only to bomb out or feel very flat in the race. “Going Deep” then reveals some of the more subtle after effects from the illness still present, probably at a cellular (metabolic) level.2
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See this podcast on Inside Exercise with Dr. Ben Levine for more information. Also check out this episode with Dr. Andre La Gerche, an outstanding masters athlete and Sports Cardiologist.
Gordo’s lactate testing around the time of his covid positive, as well as his wife’s covid positive, picked up a possible change in metabolic function. Lactate values were elevated over normal.