Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.
A few months ago on our podcast, my co-host (what other cultures call a “wife”), Megan, mentioned how she started using a WHOOP heart-rate-tracking strap because of the Journal feature. The Journal lets users log life events, tracking how the body responds over time. Megan was interested in tracking one category of activities in particular. But I’ll let you listen to the podcast to find out because this article is rated PG (may contain graphic podcast promotion).
WHOOP heard the episode and eventually signed on as a formal sponsor (promo code “SWAP” for 15% off! Selling out never felt so life-affirming!). Many of our athletes got WHOOP straps, letting us track recovery patterns over time. Some training logs became unofficial Journals, with athletes reporting added data each day. And something jumped out pretty quickly. Those unexplained drops in recovery that would occasionally pop up?
Often, it was the day after an athlete drank alcohol.
We weren’t just seeing spurious patterns. An article by WHOOP states: “of all the behaviors available to record in the WHOOP Journal, drinking alcohol is the one with the single greatest negative impact on next-day recovery.” They even recorded a podcast on elite performers sharing stories of alcohol’s impact on their bodies.
Back in 2019, I wrote an article on the uncertain, individual-specific science of alcohol and athletic performance. One of the big uncertainties was related to how alcohol consumption may affect longer-term athletic trajectories based on changes to recovery and adaptation. That article reviewed some possible impacts to sleep, the immune system, endocrine system, and metabolic processes, with no satisfying conclusion. These heart-rate-tracking apps could theoretically integrate many of the uncertain variables into a global recovery analysis. What might that heart-rate analysis add to the discussion? Let’s dig into some of the science.
Heart Rate Variability (HRV)
WHOOP, Oura Ring, and other tracking tools often look at similar metrics. While wrist-based straps are less accurate than chest straps at measuring heart rate during intense running, they are reliable at rest. Resting heart rate provides insight into recovery status because it increases in periods of higher stress. That’s the horse-and-buggy, old-school data. HRV is the new hotness.
HRV measures the gap between heartbeats. As stated by a 2017 article in the Frontiers in Public Health journal, “a healthy heart is not a metronome.” The autonomic nervous system controls involuntary behaviors, like heartbeats or our unquenchable attraction to Timothée Chalamet. The parasympathetic branch of the autonomic nervous system responds to information from internal organs (“rest and digest”). The sympathetic branch responds to stress (“fight or flight”). When the nervous system is overloaded, HRV goes down as the heart essentially goes on autopilot, less receptive to nervous system signals.
A 2018 review article in the journal Psychiatry Investigations found that HRV correlates with stress, validating its use as one data point to inform stress management practices. There are tons of cool studies of how it can be used in practice (though the jury is still out on its universal effectiveness for athletes). For example, a 2018 study in the European Journal of Applied Physiology monitored the HRV of 24 elite skiers in a high-altitude training camp. In the experimental group, if HRV dropped too much (30%+) or too long (multiple days) relative to an individual baseline, athletes reduced training; if it increased or stayed the same, they would increase training. Training using shifts in HRV as a general guideline led to fitness increases, along with improved HRV.
While HRV is just one data point to inform training, recovery, and adaptation, it provides helpful clues into what stress we are handling, and what stress we aren’t. Hard training days can reduce HRV for some athletes. For example, I have a moderately low baseline of 70 (I don’t think I’ve remembered to breathe while writing the last 2 paragraphs, so it makes sense). The first time I did a long bike with Megan this season, it dropped to 51, around the 30% threshold in the 2018 study. Normal life stress also reduces HRV. My lowest reading yet was 41, the day after a short recovery jog, but when I heard tough news for a loved one. Care Bears wish they could care as hard as I do. Care swag.
And alcohol works similarly for my body. For me, it’s approximately a hard workout, even in relatively small quantities. Megan responded similarly. So did some athletes on the team. Is it signal, or is it noise? Confounding variables that make alcohol a passenger on the stress train (i.e. maybe people drink in more stressful situations), or is alcohol a stress conductor?
Alcohol theoretically can cause a change in the balance of the autonomic nervous system, impacting HRV, as outlined in this 1999 study in the Experimental and Clinical Psychopharmacology journal. Way back in a 1994 study, researchers found that intoxication reduces HRV through this diminished nervous system regulation. A 2010 study in the American Journal of Physiology found that one glass of red wine had no impact on HRV, while 2 glasses decreased HRV by 28-33%, due partially to “augmented sympathetic HR modulation.” There are studies that fall all over the place, with a 2013 study in Psychophysiology even finding that some alcohol consumption may increase HRV in healthy young adults that do not drink heavily, and a 2005 study in the Heart journal finding that moderate wine consumption could increase HRV in women with coronary heart disease.
A 2019 review article in the Pharmacology, Biochemistry and Behavior journal found variable responses based on background with alcohol, with a general relationship between consumption and reduced HRV. A 2011 review article in Alcoholism Clinical and Experimental Research found a similar relationship across 6 of the 8 studies on healthy, non-alcoholic people. And there are SO MANY MORE STUDIES. When something is relatively easy to measure (HRV) and there’s an activity that many volunteers like to do (drink alcohol), the journal articles can blot out the sun. The somewhat variable findings likely mean that there are numerous underlying mechanisms competing to be the top dog driving causation.
But studies have limitations. The nature of an experimental group requires intentionally changing some variables and monitoring subsequent changes, and that change itself could impact results. It’s like “white-coat syndrome” where some people measure higher blood pressures in the doctor’s office. And since HRV is trying to measure stress, placing different stresses on study participants might paint a cloudy picture.
That’s why the WHOOP data is so fascinating to me.
WHOOP has thousands of real-world participants who are opting into passive observation and behavior monitoring, often over years. So does Oura Ring. And basically everything these companies say supports what I have seen in coaching: alcohol can be bad for recovery for some people, even well short of alcohol abuse.
WHOOP users who report drinking even a small amount of alcohol show next-day reductions in HRV of over 10%, with resting heart rate going up 3 beats, and overall recovery down 8%. Those are pretty stunning totals considering the sheer volume of data being collected. Quitting alcohol consumption also improved sleep and recovery. A WHOOP analysis from the 2015-2016 season on 148 collegiate athletes found that drinking alcohol reduced HRV by 22.7% and increased resting heart rate by 16.2%. Those effects could linger in recovery metrics for up to 4 days. A 2019 Conference Paper used Oura Ring data for 10 subjects to reach similar findings. The paper included this line that struck me hard the first time I read it: “the effect of alcohol has similar characteristic in nearly all individuals, manifesting as an increase of RHR and decrease of HRV in the night with alcohol compared to the rest of the nights of the week (the highest RHR and lowest HRV occur for every subject after the alcohol intake night).”
So yes, the science is uncertain. There is a chance that alcohol doesn’t negatively impact recovery at all if the HRV changes are associated with heart rate changes rather than being driven by the nervous system. HRV might not even be an appropriate metric to track for athletes in the first place. Maybe wine is fine, maybe it depends on the person, maybe people like me are seeing what they want to see, after having loved ones drink too much and face negative health outcomes as a result.
But I think I’m done drinking.
My last sip is in the rear-view mirror, I’m pretty sure. I really, deeply care about my athletics; about having the energy to do whatever good I can with the time I have; about being quick with a laugh at 9 AM and not just 9 PM. If I end up drinking tomorrow, we can add it to the pile of instances where I have been a hypocrite. As of now, though, based on what I have seen in coaching… I’m done.
Whatever decision you make with alcohol, you are enough and you are awesome just as you are. Perhaps this article is only a reminder to check in about what makes you feel good and what doesn’t. Studies won’t have that answer. Nor will a strap on your wrist or a ring on your finger. And if something makes you feel good, go for it.
But check-in with yourself to see if you feel good tomorrow, too.
David Roche partners with runners of all abilities through his coaching service, Some Work, All Play. With Megan Roche, M.D., he hosts the Some Work, All Play podcast on running (and other things), and they wrote a book called The Happy Runner.