We Drink More Alcohol on Gym Days

A new Northwestern Medicine® study finds that on days when people exercise more - typically Thursdays to Sundays - they drink more alcohol, too.

This is the only study to use smartphone technology and a daily diary approach for self-reporting physical activity and alcohol use.

“Monday through Wednesday people batten down the hatches and they cut back on alcohol consumption,” said David E. Conroy, lead author of the study. “But once that ‘social weekend’ kicks off on Thursdays, physical activity increases and so does alcohol consumption.”

Conroy is a professor of preventive medicine and deputy director of the Center for Behavior and Health at Northwestern University Feinberg School of Medicine. He also is a faculty affiliate of the Methodology Center at The Pennsylvania State University, where the research was conducted.

The study was published online in Health Psychology, an American Psychological Association journal.

“Insufficient physical activity and alcohol use are both linked to many health problems, and excessive alcohol use has many indirect costs as well,” Conroy said. “We need to figure out how to use physical activity effectively and safely without having the adverse effects of drinking more alcohol.”

What impact does alcohol have on your fitness regime?

Unfortunately, toasting your gym session with post-exercise drinks at home or down the pub can undo all the good work you’ve just put in. There’s 180 calories in the average pint of lager and 159 calories in a 175ML glass of 13% ABV white wine, so you could end up topping up the weight you thought you’d lost through your fitness regime in no time at all. For instance, if you’ve just run for half an hour it will only take two pints to put back on the calories you’ve just burned off through exercise.

The way alcohol is absorbed by the body can also reduce the amount of fat you’re able to burn by exercising. Because your body isn’t designed to store alcohol, it tries to expel it as quickly as possible. This gets in the way of other processes, including absorbing nutrients and burning fat. So as well as slowing down the burning of calories, alcohol gets in the way of the nutritional benefits of the healthy meals you eat.
Running on empty

Fitness experts agree that to get the most from cardiovascular exercise such as running or swimming, you have to put in the physical effort. But while your hangover may make a less hectic workout feel welcome, it’s harder to build up the head of steam you need to stay in shape when you have a headache, and nausea is beginning to kick in. The night before’s alcohol leaves your body dehydrated, even before your session starts.

One hundred and fifty study participants, ages 18 to 89, recorded their physical activity and alcohol use in smartphones at the end of the day. They did so for 21 days at a time, at three different times throughout one year.

We Drink More Alcohol on Gym Days' Other studies on physical activity and alcohol relied on people self-reporting their behavior over the past 30 days.

“In this study, people only have to remember one day of activity or consumption at time, so they are less vulnerable to memory problems or other biases that come in to play when asked to report the past 30 days of behavior,” Conroy said. “We think this is a really good method for getting around some of those self-report measurement problems.”

The previous studies, which relied on 30-day self-reporting, concluded that physically active people tend to drink more alcohol - something this study did not find.

“We zoomed in the microscope and got a very up-close and personal look at these behaviors on a day-to-day basis and see it’s not people who exercise more drink more - it’s that on days when people are more active they tend to drink more than on days they are less active,” Conroy said. “This finding was uniform across study participants of all levels of physical activity and ages.”

Effects of alcohol on sport performance

Overall, alcohol is detrimental to sports performance because of how it affects the body during exercise. It does this in two main ways.

Firstly, because alcohol is a diuretic, which means it makes your kidney produce more urine, drinking too much of it can lead to dehydration. Exercising soon after drinking alcohol can make this dehydration worse because you sweat as your body temperature rises. Combined, sweating and the diuretic effect of exercise make dehydration much more likely. You need to be hydrated when you exercise to maintain the flow of blood through your body, which is essential for circulating oxygen and nutrients to your muscles.

“Dehydration leads to reduced performance,” says Professor Greg Whyte, an expert in sports performance. “Hydration also helps control your body temperature so you’re more likely to overheat if you’ve been drinking alcohol.”

Secondly, alcohol interferes with the way your body makes energy. When you’re metabolising or breaking down alcohol the liver can’t produce as much glucose, which means you have low levels of blood sugar. Exercise requires high levels of sugar to give you energy. If your liver isn’t producing enough glucose, your performance will be adversely affected. “If your body is forced to run from your supplies of fat rather than blood sugar, you will be slower and have less energy and won’t be able to exercise as intensely,” says Professor Whyte. As a result, your coordination, dexterity, concentration and reactions could be adversely affected too.

Both of these effects are immediate which is why it’s not advised to exercise or compete in sport soon after drinking alcohol.
Exercising the day after the night before

Drinking alcohol the night before could have a negative influence on your performance the following day. Sports dietitian Jane Griffin says: “It’s not possible to perform at your best if you’re feeling any of the effects normally associated with a hangover such as dehydration, a headache and hypersensitivity to outside stimuli such as light and sound.”

Trying to avoid a hangover? Get some simple tips here

Even if you’re not experiencing the symptoms of a hangover, elite sports nutritionist Matt Lovall adds that “exercising the day after drinking alcohol can mean you have an all-round lower quality training session or sporting activity.”

You’ll lack strength and power, be less likely to make split second decisions and more likely to feel tired quicker because your body won’t be able to clear out the lactic acid you produce when you exercise. “This is because your liver will be working harder to get rid of the toxic by-products of alcohol in your system,” explains Lovall.

For all of these reasons, experts suggest avoiding alcohol the night before exercise whether you’re due to go for a heavy session at the gym or compete in a team game. However, if you do decide to drink, both Lovall and Griffin advise sticking to just one drink with food.

Through future studies at the Center for Behavior and Health at Feinberg, Conroy hopes to discover what drives people to drink more on days they exercise more.

“Perhaps people reward themselves for working out by having more to drink or maybe being physically active leads them to encountering more social situations where alcohol is consumed - we don’t know,” Conroy said. “Once we understand the connection between the two variables we can design novel interventions that promote physical activity while curbing alcohol use.”

The National Institute on Aging grant AG035645 and the National Institute on Drug Abuse grant P50 DA010075 funded this study. Other study authors include Nilam Ram, Aaron L. Pincus, Donna L. Coffman, Amy E. Lorek, Amanda L. Rebar and Michael J. Roche of The Pennsylvania State University.


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