How respiratory rate can signal early COVID-19 changes in the body

Originally published on April 1, 2020

Respiratory rate can help flag early COVID-19 changes in the body when you compare it against your own baseline. In this article, you will learn why breathing rate during sleep became one of the most useful signals WHOOP was studying early in the pandemic, how it differs from resting heart rate and HRV, and how to use that information without treating it like a diagnosis.

In Episode 67 of the WHOOP Podcast, Emily Capodilupo, Senior Vice President of Research, Algorithms, and Data at WHOOP, explains how lower respiratory tract infections can change breathing before symptoms are obvious, why personal baselines matter more than a generic normal range, and how WHOOP members can share those trends with a clinician.

To listen to episode 67 in full, head to the WHOOP Podcast on YouTube.

Why does respiratory rate matter during COVID-19?

Respiratory rate mattered early in the pandemic because COVID-19 often presented as a lower respiratory tract infection. That meant the lungs could show stress before other daily signals became easy to interpret.

In Episode 67 of the WHOOP Podcast, Capodilupo explains that the key mechanism is lung efficiency. When the virus affects the alveoli, the tiny air sacs where oxygen and carbon dioxide exchange occurs, each breath becomes less efficient. The body compensates by taking more breaths. That is why respiratory rate tracking during the COVID-19 pandemic became a priority for WHOOP research.

That work moved quickly because WHOOP already had research relationships in place with the Appleton Institute at CQUniversity Australia and brought in the Cleveland Clinic for added infectious disease and epidemiology expertise. Capodilupo notes that the pre-existing partnership helped the team move faster on COVID-19 analysis than a brand-new study normally could.

Capodilupo describes the mechanism plainly:

"The actual infected cells are the alveoli [...] if, as those alveoli get damaged, we start to see that gas exchange [...] becomes less and less efficient. In order to compensate for that loss in efficiency, you have to take more breaths."

What you should take away

• Respiratory rate can rise early in COVID-19 because lung efficiency drops as the infection affects the lower respiratory tract.
• Respiratory rate during sleep is useful because breathing conditions are more stable overnight than during daytime activity.
• WHOOP studied respiratory rate closely during COVID-19 because it reflected a lung-specific mechanism, not just general stress.

If you want to hear Capodilupo unpack why lung physiology can change breathing early, listen to the full episode on Youtube.

How can respiratory rate rise before symptoms start?

That lung mechanism leads directly to the next question: timing. Respiratory rate can rise before symptoms are obvious because viral damage builds during the incubation period before the body reaches the point where you consciously feel sick.

Capodilupo walks through how viruses reproduce inside host cells, burst those cells, and gradually increase viral load. Early on, the body can compensate for some damaged cells. Symptoms show up later, once enough cells are affected that organ function starts to suffer. With SARS-CoV-2, that silent window was especially important because transmission often happened before a person felt ill.

She also notes that the incubation period could be long. Many people moved from exposure to symptoms in roughly three to six days, but the period could extend to 14 days, which aligned with quarantine guidance from the Centers for Disease Control and Prevention.

Capodilupo frames the risk this way:

"One thing that makes the SARS-CoV-2 virus particularly dangerous is that during that asymptomatic incubation period, that is when they think most of the transmission is occurring."

What you should take away

• Respiratory rate may rise before symptoms because viral damage can affect lung function before illness is easy to feel.
• COVID-19 drew attention to this pattern because transmission could happen during the asymptomatic incubation period.
• A long incubation window made early physiological clues more useful for deciding when to isolate or seek testing.

If you want to hear Capodilupo go deeper on incubation and asymptomatic spread, listen to the full episode on Youtube.

What makes your personal baseline more useful than a normal range?

Once you know timing matters, interpretation matters just as much. Your baseline is more useful than a generic normal range because a large change for you can still look ordinary on paper.

Capodilupo says a typical resting respiratory rate is about 12 to 20 breaths per minute, but context is everything. If an athletic person usually sits around 14 breaths per minute and then rises to 17, that is still within the general range, yet it is a large personal shift. In healthy people, she adds, respiratory rate varies very little from day to day, often by less than one breath per minute over long periods.

That stability showed up in early member data. In one confirmed case, a member ranged from 15.4 to 16.1 breaths per minute during the 10 days before exposure, then jumped to 18.1 and 18.5 when illness hit. WHOOP later collected more examples in case studies of respiratory rate during COVID-19.

Capodilupo gives a concrete example:

"If somebody who is athletic has a resting respiratory rate of 14 breaths per minute and then it goes up to 17 breaths per minute, percentage-wise that is a really meaningful increase."

What you should take away

• A personal baseline is more informative than a one-time reading inside a broad normal range.
• Respiratory rate is useful partly because it is usually very stable from night to night in healthy people.
• A change from 14 to 17 breaths per minute can deserve attention even though 17 still falls inside a standard range.

For Capodilupo's full take on baseline shifts and why they stand out so clearly, listen to the full episode on Youtube.

Which WHOOP signals are more specific, and which are less specific?

After baseline comes specificity. Respiratory rate was more specific than resting heart rate and HRV for this use case, but none of these signals could diagnose COVID-19 on their own.

Capodilupo says confirmed COVID-19 cases often showed higher resting heart rate and lower HRV as well. The problem is that both metrics respond to many other inputs, including hard training, alcohol, and illness in general. Respiratory rate was more focused on lower respiratory stress, which made it more useful for pattern recognition, even though it still was not COVID-19-specific.

Other factors could elevate respiratory rate too. Capodilupo mentions altitude as one example because thinner air can push breathing rate upward. Asthma, allergies, bronchitis, tuberculosis, and other lower respiratory conditions could also change the signal. That is one reason later articles and follow-up episodes, including what WHOOP can tell you about COVID-19 and respiratory rate research and the pandemic, kept returning to the same caution: useful does not mean diagnostic.

Capodilupo makes the tradeoff clear:

"Resting heart rate will go up if you had a really tough workout, if you went to bed drunk, and if you are sick with pretty much anything."

What you should take away

• Resting heart rate and HRV can reflect illness, but they are less specific because many stressors change them.
• Respiratory rate can be a cleaner signal for lower respiratory stress, but it still cannot confirm COVID-19 by itself.
• Altitude, asthma, allergies, bronchitis, and other lung-related issues can also raise respiratory rate.

If you want to hear Capodilupo unpack why some metrics are cleaner than others, listen to the full episode on Youtube.

How should WHOOP members use respiratory rate in practice?

The practical use is simple: watch for deviations from baseline, log relevant symptoms, and treat the data as information for a clinician, not a diagnosis. WHOOP reports respiratory rate during sleep as the median value across the night, which makes trend-watching easier.

At the time of Episode 67 of the WHOOP Podcast, respiratory rate was already available in the web app and was being added to the WHOOP app. Capodilupo and Ahmed also pointed members to the WHOOP Journal so they could tag COVID-19 status and symptoms, helping build a de-identified dataset for research. That work later informed broader updates, including how respiratory rate contributed to Recovery in the Recovery algorithm update.

Capodilupo also stressed the clinical use case. A clear deviation from baseline can give a doctor one more piece of context, especially when care is happening through telemedicine and testing access is limited. WHOOP is not a medical device, and the data should not replace professional care.

Her advice was direct:

"If you have a baseline [...] and now you know that your respiratory rate is elevated, that is information that you can give to your doctor."

What you should take away

• WHOOP measures respiratory rate during sleep and presents it in a way that makes personal trends easier to review.
• The most useful response to an unusual respiratory rate is to combine it with symptoms, exposure history, and clinical guidance.
• WHOOP Journal entries can add context for both personal interpretation and broader de-identified research.
• Respiratory rate data is most valuable when it supports a decision to monitor more closely, isolate, or contact a clinician.

The bottom line

• Respiratory rate became a key COVID-19 signal because the disease often stressed the lower respiratory tract early in its course.
• Respiratory rate can rise before symptoms are obvious because viral damage can reduce gas-exchange efficiency during the incubation period.
• Personal baseline matters more than a broad normal range when you are trying to spot an unusual change in respiratory rate.
• A jump from 14 to 17 breaths per minute can be important even though 17 still sits inside a standard resting range.
• Resting heart rate and HRV often move with illness, but they are less specific than respiratory rate for lower respiratory stress.
• Respiratory rate is still not diagnostic because altitude, asthma, bronchitis, allergies, and other conditions can also raise it.
• WHOOP data is most useful when it helps you recognize a change early and share that context with a clinician.

Frequently asked questions about things discussed in this episode

How does WHOOP measure respiratory rate?

WHOOP measures respiratory rate during sleep by detecting cyclical heart rate changes linked to breathing and reports the median breaths per minute across the night.

What does WHOOP do with respiratory rate changes?

WHOOP shows respiratory rate against your personal baseline so unusual night-to-night changes are easier to spot than a single reading viewed in isolation.

How does WHOOP use respiratory rate alongside HRV and resting heart rate?

WHOOP presents respiratory rate alongside HRV and resting heart rate because all three can shift with illness, but Episode 67 explains that respiratory rate can be a cleaner signal for lower respiratory stress.

What does WHOOP recommend if respiratory rate jumps above baseline?

WHOOP recommends treating an elevated respiratory rate as useful context to monitor and share with a clinician, rather than as proof of COVID-19 or any other disease.

How does WHOOP help track COVID-19-related context?

WHOOP helps track COVID-19-related context through the WHOOP Journal, where members could log infection status and symptoms to add context to nightly physiological trends.

For respiratory infections, the value of WHOOP is seeing whether last night's breathing pattern broke from your usual range before that change is easy to feel.