Lesson from a Bachelor Run: The Science of Alcohol and Running

My buddy is an avid runner, so instead of the traditional bachelor party to celebrate his upcoming wedding, we threw him a “bachelor run.” The idea was straight forward: a group of us would hit 6 breweries over a 14-mile loop around Seattle. And the July heat wouldn’t stop us from looking classy as we donned dress shirts and running shorts (Pro Tip: apply your favorite anti-chafe liberally to protect your neck).

Not surprisingly, we were no longer the same caliber of runners at the end of our adventure as at the start. From bar to bar, we could feel ourselves getting slower and the legs becoming heavier. It was a feeling usually reserved for the final trudge in a marathon. But this wasn’t pavement-induced, or the consequence of holding race-pace beyond our comfort zone. Instead, as Jamie Foxx says, you can “blame it on the a-a-a-a-alcohol.”

It didn’t take this experiment in July to realize that alcohol won’t improve running performance. After all, alcohol isn’t on WADA’s list of banned substances for good reason: they don’t want to waste ink. But running and alcohol are becoming increasingly intermingled. There’s been an explosion in the popularity of the beer mile (and wine mile?), an increased number of craft beer and winery races, and there often seems to be beer now at the finish line of most big races. And on St. Patrick’s Day, according to my Facebook and Instagram feeds, everyone is racing and drinking (and not necessarily in that order).

But what are the effects of alcohol on running? Can it be so bad? Alcohol features prominently in the lives of many athletes. Social media has given us a glimpse into the lives beyond the race for some of our most revered runners and I’m comforted when I see them holding a beer or cocktail. Refreshing to know you can still drink and justify the five-ring tattoo.

 

Why is alcohol so alluring?

Alcohol has a number of actions in the brain that make you want to grab a cold one after a long day at work or a hard workout. For one, alcohol activates the brain’s reward system by increasing the amount of the brain chemical, dopamine, that gets dumped into the nucleus accumbens, the brain’s reward center. But it doesn’t do so directly. Instead, alcohol increases inhibitory brain function by elevating the activity of the brain’s GABA system. The GABA system acts as a break in the brain to reduce communication between brain cells, but because of the complex way in which brain cells are connected, alcohol’s effect on the GABA system actually  causes more dopamine to be dumped into nucleus accumbens. This spike in dopamine tells the brain, “Hey, that was good! Let’s do it again!” As a result, you plan a bachelor run centered around two dopamine-increasing activities: running and drinking. 

By increasing the inhibitory chemical GABA, alcohol also reduces the activity of a brain region called the amygdala (Latin for almond). This tiny, almond-shaped brain structure is one of the most sensitive brain regions to low amounts of alcohol. Alcohol’s effects in this region are why a single drink causes you to relax. But by increasing GABA, alcohol also has numerous effects in other brain regions that become affected as you increase how much you consume, which impact how you run and how well you recover.

 

Now I have to pee…

We drank our first beer after a mile-and-a-half warmup that took us over the Ballard Locks. I entered the run after having a light lunch, which delayed the alcohol from making it into my bloodstream, so my 5% pale ale didn’t have a strong effect. The rate at which alcohol makes its way into the bloodstream depends on one’s stomach contents; the more in your stomach, the longer it takes alcohol takes to be absorbed (keep that in mind for your next beer mile). Generally, this effect can take between a couple of minutes to a half an hour. 

I began to notice the effect of the alcohol on our way to the second brewery. I’m a lightweight and I noticed something a little off in my balance as we dodged potholes in an industrial stretch on the way to #2. This effect can be pinned to alcohol’s effect in the cerebellum, a brain region that sits at the back of the brain and, like the amygdala, is highly sensitive to disruption by alcohol. The cerebellum (Latin for little brain) contains half of all your brain cells and plays a crucial role in balance and motor coordination. Too much alcohol and you fall over; that’s alcohol impairing your cerebellum. The sobriety test for drunk drivers is essentially a measure of cerebellar function, and I was engaging in my own little test as I made my way to the next brewery. One beer, I passed.  

By the time we hit #2, I was struck by how badly I had to pee. After only one beer? That’s not all that much fluid. But alcohol inhibits a hormone called vasopressin (a.k.a., anti-diuretic hormone), which is responsible for its diuretic effect. One important concern for runners consuming alcohol is its dehydrating effect. For every gram of alcohol consumed, you expel an extra 10 milliliters (ml) of excess urine. A standard drink, defined as a 12oz beer at 5% alcohol, has 14 grams of alcohol. A pint, which is the go-to size at most craft breweries, has 16oz, or 568 ml of fluid, and 18.7 grams of alcohol (again, assuming 5% alcohol). So you’ll get an excess of 187ml of urine with every 5% pint. Considering that the average bladder holds 400-600ml, that’s a substantial amount of excess fluid, especially given my attempt to be well-hydrated heading into the run.

Still, based on the math, you’re much better off chugging a beer post-race than a cocktail since spirits are far worse for dehydration. For instance, consuming a 25ml whiskey soda containing 10ml of whiskey (40% alcohol) drink mixed with 15ml of soda, will lead to 100ml of excess urine for a net loss of 85ml fluids. Not a great idea if you’re trying to rehydrate!

Okay, no more math.

 

Legs are getting heavy

At brewery #3 in Seattle’s Fremont neighborhood, I ordered an IPA (screw it, commit to this). The alcohol is clearly beginning to impact my judgement, a sign of its impairing effects now to the prefrontal cortex, that sits at the front of the brain. The group follows up their third beer with a race to the top of the hill in Seattle’s GasWorks Park, reflecting our reduced inhibitory control which also signifies impaired prefrontal cortex functioning. 

Charging up the hill, my legs felt zapped of energy. I shouldn’t have been surprised. Alcohol causes your blood vessels to dilate, diverting much needed blood away from your muscles. One of the benefits of training is to enhance blood flow to the muscles, but now it’s been rerouted.  Blood carries oxygen and glucose to your muscles which are necessary ingredients in aerobic cellular respiration, the process that creates the energy to power your muscles during exercise. With less blood reaching the muscles during this uphill surge, they quickly became depleted of energy.

 

It’s a long haul 

The 5k stretch to Ravenna Park between brewery #3 to #4 was our longest. At the time, I was running around 90 miles/week, but this felt like a marathon. Some of this had to do with loss of muscle strength, which generally kicks in with a blood alcohol concentration around .08%. That BAC can be achieved with only 2-3 drinks in quick succession for a 140-pound individual. A BAC of .08 is the legal limit for intoxicated driving, but was I drunk at this point? Perhaps. Feeling intoxicated is subjective and depends on a variety of factors including genetics and drinking history. But the types of stimuli you’re exposed to also contribute to your degree of intoxication. For instance, if you’re running outdoors, all the sounds, lights, temperature fluctuations, people, cars, will make you feel more drunk than if you were sitting on your couch in a temperature-controlled home. If you’re a slow beer-miler, you’ll be less aware of alcohol’s effects if you’re on an indoor track. Just saying… 

The journey to breweries #5 and #6 near Green Lake was a blur. If you’ve ever put back one too many, you understand alcohol’s memory-impairing effects, which result from alcohol’s disruption of brain processing in the hippocampus (those who took an intro-to-psychology course will remember was the brain region HM had destroyed, leaving him unable to form new long-term memories). The brain cells in the hippocampus begin to be affected at higher blood alcohol concentrations, which is why after a beer or two, you remember everything, but after 4 or 5, things get fuzzy.

Nevertheless, it’s hard to forget the bachelor arriving at bar #5 with blood dripping from his knee, elbow, and hands. No one saw it happen, but we can assume it was a combination of alcohol’s effects on the cerebellum (balance) and prefrontal cortex (decision making). 

 

Hungry and tired

At our final stop, we needed food. We were through running (thank heaven) and it was time to think about recovery. Any good training plan includes a focus on recovery, and when it comes to nutrition, a primary aim is to replenish your body’s glycogen stores. Glycogen is mainly stored in your liver and muscles, and is the primary source of energy for runners. Hitting the dreaded “wall” during a marathon occurs when your glycogen stores have been depleted. It makes sense to want to stock them. 

Relatively low amounts of alcohol can inhibit the body’s ability to store glycogen in the liver and Type I muscle fibers . Type I muscle fibers, also known as slow-twitch fibers, use oxygen to produce the energy needed for their action, so alcohol’s impact on glycogen storage is going to impact endurance athletes more than sprinters. However, if you also consume a large amount of carbohydrates with alcohol (no, the carbs from the beer don’t count), you can mitigate this issue. In a study of cyclists that completed a glycogen-depleting workout, those that only consumed alcohol following the workout had a 50% reduction in glycogen stores, but including a high-carbohydrate meal with alcohol prevented this loss. Point being, if you’re going to have a few drinks post-race, make sure they’re not your only source of carbs. Carbo-loading with only alcohol will hurt your next performance!

While the bachelor run ended by dinner time, there was still alcohol in my blood by the time my head hit the pillow. And that’s a problem. Runners need a lot of sleep, and they especially need time in the late stages of sleep when important hormones, such as growth hormone, are released into your blood to help repair muscles. 

The problem is, alcohol reduces the amount of time you spend in the late stages of sleep including REM sleep, the critical sleep stage where dreaming occurs. In turn, time spent in the light, non-restful sleep stage 1 increases. This will leave you more tired for your run the next day and have less circulating hormones to regulate muscle growth, stress, and appetite. Reductions in sleep will also decrease your motivation to finish that final interval in your workout. And of course, if you’re still dehydrated from alcohol’s diuretic effects, that won’t help either. 

But do I regret the bachelor run? Of course not! It was a great success, and sometimes, the idea of mixing up the routine, being social with the friends with whom you share countless miles of pain, and celebrating a good friend is worth a slight blip in the training trajectory. The idea of drinking and running again, however, is dreadful. I’ll stick to running, and save the beer for afterwards. Turns out, mice too, when given a choice between a running wheel or alcohol, will choose to run. Can’t blame ‘em.

Hear Josh on The BibRave Podcast in Episode #79: Drunk on the Run.

 

Josh Kaplan, Ph.D., is a neuroscientist at the University of Washington and freelance writer specializing in cannabis science. Josh developed a passion for running while in graduate school living in Portland, Oregon, reaching PRs of 1:12:52 in the Half and 2:34:11 in the marathon. He is passionate about science education and engages students of all backgrounds through his writing and classroom teaching.

You can link to his work by visiting neurokaplan.com or follow him on Twitter @neurokaplan.